U.S. patent application number 17/026234 was filed with the patent office on 2021-03-25 for method of producing electrically conductive polymers and removing protein-bound substances.
The applicant listed for this patent is Yu-Sheng HSIAO, Chia-Hung SU, Shih-Chieh YEN. Invention is credited to Yu-Sheng HSIAO, Chia-Hung SU, Shih-Chieh YEN.
Application Number | 20210086144 17/026234 |
Document ID | / |
Family ID | 1000005146262 |
Filed Date | 2021-03-25 |
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United States Patent
Application |
20210086144 |
Kind Code |
A1 |
HSIAO; Yu-Sheng ; et
al. |
March 25, 2021 |
METHOD OF PRODUCING ELECTRICALLY CONDUCTIVE POLYMERS AND REMOVING
PROTEIN-BOUND SUBSTANCES
Abstract
The present invention provides an organic bioelectronic HD
device system for the effective removal of protein-bound
substances, comprising PEDOT:PSS, a multiwall carbon nanotube,
polyethylene oxide (PEO), and (3-glycidyloxypropyl)trimethoxysilane
(GOPS). The composite nanofiber platform exhibited (i) long-term
water-resistance; (ii) high adhesion strength on the PES membrane;
(iii) enhanced electrical properties; and (iv) good anticoagulant
ability and negligible hemolysis of red blood cells, suggesting
great suitability for use in developing next-generation
bioelectronic medicines for HD.
Inventors: |
HSIAO; Yu-Sheng; (New Taipei
City, TW) ; YEN; Shih-Chieh; (New Taipei City,
TW) ; SU; Chia-Hung; (New Taipei City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HSIAO; Yu-Sheng
YEN; Shih-Chieh
SU; Chia-Hung |
New Taipei City
New Taipei City
New Taipei City |
|
TW
TW
TW |
|
|
Family ID: |
1000005146262 |
Appl. No.: |
17/026234 |
Filed: |
September 20, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62903954 |
Sep 23, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 61/30 20130101;
B01D 2311/2684 20130101; D01F 1/09 20130101; B01D 2313/345
20130101; C08L 2203/20 20130101; B01D 61/243 20130101; C08L 65/00
20130101; B01D 71/68 20130101; C08L 2312/08 20130101; B01D
2311/2626 20130101; D01D 5/003 20130101; C08J 3/212 20130101; D01D
1/02 20130101; D10B 2509/00 20130101; C08L 2203/12 20130101; A61M
1/1621 20140204 |
International
Class: |
B01D 71/68 20060101
B01D071/68; A61M 1/16 20060101 A61M001/16; C08J 3/21 20060101
C08J003/21; C08L 65/00 20060101 C08L065/00; D01D 1/02 20060101
D01D001/02; D01D 5/00 20060101 D01D005/00; D01F 1/09 20060101
D01F001/09; B01D 61/24 20060101 B01D061/24; B01D 61/30 20060101
B01D061/30 |
Claims
1. A method for producing an electrically conductive polymer,
comprising: (a) providing a PEDOT:PSS solution including carbon
nanotubes and a crosslinking agent; (b) blending the PEDOT:PSS
solution with an additive solution to acquire a quaternary blend
solution; and (c) electrospinning the quaternary blend solution to
form the electrically conductive polymer, wherein the additive
solution is ranged 5.about.30 wt % based on a total weight of the
quaternary blend solution.
2. The method of claim 1, wherein the additive solution comprises
polyethylene oxide (PEO) solution, polyvinyl alcohol (PVA)
solution, polyethyleneimine (PEI) solution, poly(acrylic acid)
(PAA) solution, poly(styrenesulfonate) (PSS) solution,
Polyvinylpyrrolidone (PVP) solution, polyacrylamide (PAM) solution,
poly(ethyl exazoline) solution, poly-lysine solution,
poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide)
(PPO-PEO-PPO) triblock copolymers solution, poly(ethylene
oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO)
triblock copolymer solution, an alginate solution, hyaluronic acid
(HA) solution, a gelatin solution, a collagen solution,
polyglutamic acid (PGA) solution, a chitin solution, a chitosan
solution, a cellulose solution or a combination thereof.
3. The method of claim 1, wherein the carbon nanotubes are ranged
1.about.3 wt % based on total weight of the PEDOT:PSS solution.
4. The method of claim 1, wherein the crosslinking agent is
(3-glycidyloxypropyl)trimethoxysilane.
5. The method of claim 3, wherein the
(3-glycidyloxypropyl)trimethoxysilane is ranged 1.about.10 wt %
based on total weight of the PEDOT:PSS solution.
6. The method of claim 1, further comprising thermal treatment of
the electrically conductive polymer after the step (c).
7. The method of claim 6, wherein the thermal treatment is carried
out under 80.about.150.degree. C.
8. The method of claim 1, wherein a ratio of PEDOT and PSS is
1:2.5.about.1:6.
9. An electrically conductive nanofiber mat produced from the
method of claim 1.
10. A bioelectronic interface device, comprising: a dialysis
membrane; a first electrode coated on the dialysis membrane; and an
electrically conductive nanofiber mat of claim 11 as a second
electrode coated on the dialysis membrane.
11. The device of claim 10, wherein the dialysis membrane comprises
a polyethersulfone (PES) membrane, a cellulose triacetate (CTA)
membrane, an ethylene vinyl alcohol (EVAL) membrane, a
polyacrylonitrile (PAN) membrane, a polyester polymer alloy (PEPA)
membrane, a polymethylmethacrylate (PMMA) membrane, a polysulfone
(PS) membrane, a regenerated cellulose (RC) membrane, or a
cellulose diacetate (CDA) membrane.
12. The device of claim 10, wherein the first electrode is a
counter electrode or a working electrode.
13. The device of claim 12, wherein when the first electrode is the
counter electrode, the second electrode is the working electrode;
when the first electrode is working electrode, the second electrode
is the counter electrode.
14. The device of claim 10, wherein the first electrode comprises
an Ag/AgCl electrode, a silver (Ag) electrode, a gold (Au)
electrode, a platinum (Pt) electrode, an iridium (Ir) electrode, a
Pt/Ir alloy electrode, an iridium oxide electrode, a titanium (Ti)
electrode, or a titanium nitride (TiN) electrode.
15. The device of claim 10, further comprising a reference
electrode coated on the dialysis membrane.
16. The device of claim 15, wherein the reference electrode
comprises an Ag/AgCl electrode, a silver (Ag) electrode, a gold
(Au) electrode, a platinum (Pt) electrode, an iridium (Ir)
electrode, a Pt/Ir alloy electrode, an iridium oxide electrode, a
titanium (Ti) electrode, or a titanium nitride (TiN) electrode.
17. A method for removing protein-bound substances, comprising: (a)
introducing a biological fluid sample to a bioelectronic interface
device of claim 10; and (b) providing an electrical stimulation to
reduce binding rate between proteins and the protein-bound
substances.
18. The method of claim 17, wherein the electrical stimulation
comprises a cyclic voltammetric sweep.
19. The method of claim 18, wherein a potential signal of the
cyclic voltammetric sweep is within a voltage range from -3 to +3
V.
20. The method of claim 17, wherein the electrical stimulation
increases retention of the protein.
21. The method of claim 17, wherein the electrical stimulation
increases adsorption amount or dialysis efficiency of the
protein-bound substances.
22. The method of claim 17, wherein the proteins dissociates from
the bioelectronic interface device after the step (b).
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 62/903,954, filed on Sep. 23, 2019, the
disclosure of which is incorporated herein in its entirety by
reference.
FIELD OF INVENTION
[0002] The present invention relates to a method of producing an
electrically conductive material for blood purification; in
particular, the present invention relates to a method of producing
an electrically conductive material for removing protein-bound
substances.
BACKGROUND OF THE INVENTION
[0003] Kidneys are organs that can filter waste metabolites from
whole blood, while also regulating blood pressure and electrolyte
balance. Symptoms of kidney failure result from the accumulation of
uremic toxins in the blood. The rate of chronic kidney failure,
causing chronic kidney disease (CKD) as well as end-stage renal
disease (ESRD), is increasing rapidly worldwide. When the kidneys
no longer work effectively, the concentration of uremic toxins will
increase, resulting in increasing risk of mortality. Continuous
ambulatory peritoneal dialysis (CAPD), hemodialysis (HD), and
kidney transplantation are the three main medical treatment
modalities used at present to preserve life. Although the high
frequency of HD treatment (4 h each time, three times a week) is
inconvenient, it remains the most viable clinical therapy and the
most popular approach for the effective removal of small
water-soluble uremic toxins from the blood. Nevertheless, because
of their high protein-binding capacity, the removal of
protein-bound uremic toxins (PBUTs) using conventional HD devices
remains problematic, with only a low fraction of free-PBUTs passing
through the HD membrane. Therefore, the development of new HD
technologies for the removal of PBUTs from the human blood should
lead to substantial improvements in the outcomes of dialysis
patients.
[0004] Bioelectronic interfaces (BEIs) play key roles in
communication enhancement intervention when directly interfacing
biology with electronic devices. They can facilitate electrical
stimulation (ES) to manipulate cellular responses (e.g., biological
phenotypes and specific gene expressions) while also converting
biological events to electronic signals for efficient readout. At
present, most research into BEIs involves the application of
organic-conjugated materials (e.g., conducting polymers (CPs),
small-molecule semiconductors, and carbon materials). Relative to
inorganic BEI materials, CP-based BEIs integrated with biology have
a greater number of potential applications because of their
extraordinary manufacturing flexibility, convenient mass
production, low-temperature fabrication, intrinsic
biocompatibility, biomimetic mechanical strength, and superior
electrochemical and optical/photoelectric properties. Among CPs,
poly(3,4-ethylenedioxythiophene) (PEDOT)-based materials have
attracted the most attention for their use in bioelectronics (e.g.,
organic electrochemical transistors (OECTs), organic-electronic ion
pumps (OEIPs), and biosensors/bioelectrodes) because they allow
dynamic control over charge transport phenomenon, protein
folding/conformational transitions, and capture/release modulation
of circulating tumor cells through electrochemical doping/de-doping
processes. Developments in multiwall carbon nanotube (MWCNT)/mixed
polymer nanocomposites have been of great interest for a broad
range of bioelectronic applications, due to their mechanical
properties, blood compatibility, and unique electronic behavior. To
the best of knowledge, there have been no previous demonstrations
of robust organic BEI systems for imparting ES functions into HD
treatment.
[0005] The above information disclosed in this section is only for
enhancement of understanding of the background of the described
technology and therefore it may contain information that does not
form the prior art that is already known to a person of ordinary
skill in the art.
SUMMARY OF THE INVENTION
[0006] In the present invention, MWCNT/PEDOT:PSS nanofiber mats has
been developed as BEI-based HD devices for effective ES to reduce
the percentage of protein binding with protein-bound substances,
such as protein-bound uremic toxins (PBUTs) while preserving the
retention of bovine serum albumin (BSA), thereby improving overall
dialysis performance for the removal of protein-bound substances,
such as PBUTs. These MWCNT/PEDOT:PSS nanofiber mats, prepared using
electrospinning and thermal cross-linking, exhibited high
water-resistance and strong adhesion to conventional
polyethersulfone (PES) dialysis membranes. The present invention
has used scanning electron microscopy (SEM), transmission electron
microscopy (TEM), Raman spectrometry, X-ray photoelectron
spectroscopy (XPS), a four-point probe, cyclic voltammetry (CV),
and electrochemical impedance spectroscopy (EIS) to determine the
nanofiber structure, chemical composition, and electrical
characteristics of these MWCNT/PEDOT:PSS nanofiber mats.
Furthermore, the present invention has evaluated the
biocompatibility of the nanofiber mats (or device setup) in terms
of the anti-thrombogenicity, hemolysis ratio, platelet adhesion,
and cell viability. We have also investigated the long-term
stability of MWCNT/PEDOT:PSS nanofiber-based HD devices under ES
operation over the potential range from -3 to +3 V, preferably -0.8
to +0.8 V, as well as the effects of ES on the binding of PBUTs to
BSA proteins.
[0007] The present invention provides a method for producing an
electrically conductive polymer, comprising: (a) providing a
PEDOT:PSS solution including carbon nanotubes and a crosslinking
agent; and (b) blending the PEDOT:PSS solution with an additive
solution to acquire a quaternary blend solution; (c)
electrospinning the quaternary blend solution to form the
electrically conductive polymer, wherein the additive solution is
ranged 5-30 wt % based on total weight of the quaternary blend
solution.
[0008] In one embodiment of the present invention, the additive
solution comprises polyethylene oxide (PEO) solution, polyvinyl
alcohol (PVA) solution, polyethyleneimine (PEI) solution,
poly(acrylic acid) (PAA) solution, poly(styrenesulfonate) (PSS)
solution, Polyvinylpyrrolidone (PVP) solution, polyacrylamide (PAM)
solution, poly(ethyl exazoline) solution, poly-lysine solution,
poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide)
(PPO-PEO-PPO) triblock copolymers solution, poly(ethylene
oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO)
triblock copolymer solution, an alginate solution, hyaluronic acid
(HA) solution, a gelatin solution, a collagen solution,
polyglutamic acid (PGA) solution, a chitin solution, a chitosan
solution, a cellulose solution or a combination thereof.
[0009] In one embodiment of the present invention, the carbon
nanotubes are ranged 1-3 wt % based on total weight of the
PEDOT:PSS solution.
[0010] In one embodiment of the present invention, the crosslinking
agent is (3-glycidyloxypropyl)trimethoxysilane (GOP S).
[0011] In one embodiment of the present invention, the
(3-glycidyloxypropyl)trimethoxysilane (GOPS) solution is ranged
1-10 wt % based on total weight of the PEDOT:PSS solution.
[0012] Preferably, the present invention further comprises thermal
treatment of the electrically conductive polymer after the step
(c).
[0013] In one embodiment of the present invention, the thermal
treatment is carried out under 80.about.150.degree. C.
[0014] In one embodiment of the present invention, the thermal
treatment is carried out at least 1 hour.
[0015] In one embodiment of the present invention, the carbon
nanotubes comprise multiwall carbon nanotubes.
[0016] In one embodiment of the present invention, a ratio of PEDOT
and PSS is 1:2.5.about.1:6.
[0017] Furthermore, the present invention offers an electrically
conductive nanofiber mat produced from aforesaid electrically
conductive polymer.
[0018] Also, the present invention provides a bioelectronic
interface device, comprising: a dialysis membrane; a first
electrode coated on the dialysis membrane; and the electrically
conductive nanofiber mat described above as a second electrode
coated on the dialysis membrane.
[0019] In one embodiment of the present invention, the dialysis
membrane comprises polyethersulfone (PES) membrane, a cellulose
triacetate (CTA) membrane, an ethylene vinyl alcohol (EVAL)
membrane, a polyacrylonitrile (PAN) membrane, a polyester polymer
alloy (PEPA) membrane, a polymethylmethacrylate (PMMA) membrane, a
polysulfone (PS) membrane, a regenerated cellulose (RC) membrane,
or a cellulose diacetate (CDA) membrane.
[0020] In one embodiment of the present invention, the first
electrode is a counter electrode or a working electrode.
[0021] In one embodiment of the present invention, when the first
electrode is the counter electrode, the second electrode is the
working electrode; when the first electrode is working electrode,
the second electrode is the counter electrode.
[0022] In one embodiment of the present invention, the first
electrode comprises an Ag/AgCl electrode, a silver (Ag) electrode,
a gold (Au) electrode, a platinum (Pt) electrode, an iridium (Ir)
electrode, a Pt/Ir alloy electrode, an iridium oxide electrode, a
titanium (Ti) electrode, or a titanium nitride (TiN) electrode.
[0023] Preferably, the bioelectronic interface device further
comprises a reference electrode coated on the dialysis
membrane.
[0024] In one embodiment of the present invention, the reference
electrode comprises an Ag/AgCl electrode, a silver(Ag) electrode, a
gold(Au) electrode, a platinum(Pt) electrode, an iridium(Ir)
electrode, a Pt/Ir alloy electrode, an iridium oxide electrode, a
titanium(Ti) electrode, or a titanium nitride(TiN) electrode.
[0025] In addition, the present invention imparts a method for
removing protein-bound substances, comprising: (a) introducing a
biological fluid sample to the aforementioned bioelectronic
interface device; and (b) providing an electrical stimulation to
reduce binding rate between proteins and the protein-bound
substances.
[0026] In one embodiment of the present invention, the electrical
stimulation comprises a cyclic voltammetric sweep.
[0027] In one embodiment of the present invention, a potential
signal of the cyclic voltammetric sweep is within a voltage range
from -3 to +3V.
[0028] In one embodiment of the present invention, the electrical
stimulation increases retention of the protein.
[0029] In one embodiment of the present invention, the electrical
stimulation increases adsorption amount or dialysis efficiency of
the protein-bound substances.
[0030] In one embodiment of the present invention, the proteins
dissociates from the bioelectronic interface device after the step
(b).
[0031] Many of the attendant features and advantages of the present
invention will become better understood with reference to the
following detailed description considered in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The embodiments will become more fully understood from the
detailed description and accompanying drawings, which are given for
illustration only, and thus are not limitative of the present
disclosure, and wherein:
[0033] FIG. 1 (a) Schematic representation of the electrospinning
setup for the fabrication of MWCNT/PEDOT:PSS nanofiber mats on a
PES membrane, (b) compositional analysis of the raw materials
(MWCNT, PEDOT:PSS, PEO) and MWCNT/PEDOT:PSS nanofiber mats
incorporating various amounts of MWCNTs (NF, CNF1, CNF2, CNF3);
[0034] FIG. 2 (a-d) SEM morphologies of as-spun nanofiber mats
incorporating various amounts of MWCNTs (NF, CNF1, CNF2, CNF3),
(e-h) corresponding diameter distribution histograms of various
nanofiber mats;
[0035] FIG. 3 (a) Stacked bar chart of nanofiber mats (NF, CNF1,
CNF2, CNF3), (b, c) conductivities of annealed MWCNT/PEDOT:PSS
incorporating various amounts of the MWCNTs in form of (b) a thin
film structure and (c) a single-nanofiber structure; inset to (c):
magnified optical image of electrospun MWCNT/PEDOT:PSS nanofiber
mats deposited on IDEs; (d, e) Electrical properties of various
MWCNT/PEDOT:PSS nanofiber mats on ITO glass in 1 PBS, (d) CV curves
of NF, CNF1, CNF2, and CNF3 nanofiber mats; potential swept from
-0.8 to +0.8 V at a scan rate of 100 mV s.sup.-1; CCDs for NF,
CNF1, CNF2, and CNF3 were 0.23, 0.59, 1.29, and 1.88 mC cm.sup.-2,
respectively, (e) impedance plot of EIS spectra of NF, CNF1, CNF2,
and CNF3 nanofiber mats (frequency range: 10.sup.-1-10.sup.5
Hz);
[0036] FIG. 4 (a-d) Photographs of annealed nanofiber mats
incorporating various amounts of MWCNTs on PES membranes (NF, CNF1,
CNF2, CNF3), (e-1) SEM morphologies of (e-h) annealed nanofiber
mats (NF, CNF1, CNF2, CNF3) and (i-1) annealed nanofiber mats (with
cross-linked structures) soaked in 1 PBS buffer for 24 h. (m-p) TEM
images of annealed nanofiber mats (NF, CNF1, CNF2, CNF3);
[0037] FIG. 5 (a-d) Optical images of annealed nanofiber mats on
PES membranes after cross-cut tape adhesion tests of the samples
NF, CNF1, CNF2, and CNF3, (e) corresponding adhesion levels (ASTM
D3359) of the annealed nanofiber mats;
[0038] FIG. 6 (a, b) Coagulation times of annealed nanofiber mats
on PES membranes (NF, CNF1, CNF2, CNF3) measured using (a) APTT,
(b) PT assays, and (c) hemolysis test results of all of the
nanofiber mats. Inset to (c): photograph of RBCs exposed to (A) DI
water, (B) NF, (C) CNF1, and (D) 1 PBS, (d) pH-Dependence of the
zeta potential of annealed nanofiber mats (NF, CNF1, CNF2, CNF3)
determined using electrokinetic measurements;
[0039] FIG. 7 (a-f) Calcein-AM-stained fluorescence images of the
platelets adhered to (a) a tissue-culture polystyrene (TCPS) dish,
(b) ITO glass, (c) NF, (d) CNF1, (e) CNF2, and (f) CNF3;
[0040] FIG. 8 XPS S.sub.2p spectra of annealed MWCNT/PEDOT:PSS
nanofiber mats on the PES membrane. (a) NF sample, (b) CNF1 sample,
(c) CNF2 sample, and (d) CNF3 sample;
[0041] FIG. 9 (a, b) Schematic representations of the CNF1-based HD
device system for simulated dialysis treatment: (a) Device
architecture for single-membrane CNF1-based HD device; (b)
experimental setup for dialysis treatment, where the device was
connected through a peristaltic pump to control the flow rate of
PBUT-side and PBS-side buffers; all reservoirs were maintained in a
water bath at 37.degree. C. (c) Concept of CNF1-based HD device for
the removal of PBUTs under ES operation. (d, e) Photographs of (d)
the CNF1-based HD device and (e) the experimental setup for
dialysis treatment. (f) Cell viability of THP1 cells during 4 h of
ES operation using CNF1-based HD devices (N=3);
[0042] FIG. 10 (a) Chemical structures, (b) physicochemical
properties of the uremic toxins PC, IS, UA, and CRT; MW, molecular
weight; PSA, polar surface area, (c) removal efficiency, and (d)
dialysis efficiency for the removal of PC uremic toxins using
CNF1-based HD devices prepared with various electrospinning times
(t=0, 5, 10, 20 min); (e) Removal efficiency and (f) dialysis
efficiency for the removal of PC using various HD devices; (g, i)
Removal efficiency and (h, j) dialysis efficiency for the removal
of IS, HA, and CRT using (g, h) PES-based HD devices and (i, j)
CNF1-based HD devices;
[0043] FIG. 11 (a-c) Current responses of the CNF1 device under 4 h
of ES operation during repeated CV voltage sweeps from -0.8 to +0.8
V at a scan rate of 100 mV s.sup.-1 in (a) PC solution, (b) IS
solution, and (c) PBS buffer solution; (d) time-dependence of the
changed ratio of current density of the CNF1 device under 4 h of ES
operation in various dialysis solutions. (e-i) CV curves of the
CNF1 device during ES operation; t=0, 1, 2, 3, and 4 h;
[0044] FIG. 12 Protein binding ratios of various BSA solutions (4,
20, and 40 g L.sup.-1) preloaded with 50 ppm of the uremic toxins
(a) PC, (b) IS, (c) HA, and (d) CRT;
[0045] FIG. 13 (a) Procedures for collecting the target solution
using a centrifugal device (Vivaspin 2, 30 kDa cutoff, GE
Healthcare) and used for the detection of BSA retention and
free-PBUT ratio; (b, c) BSA retention at pH 7.4, measured using
different HD devices (PES, CNF1, CNF1-R) in (b) pre-bonded PC-BSA
solution from PBUT-side and (c) pre-bonded IS-BSA solution from
PBUT-side; (d, e) Free-PBUT ratio at pH 7.4, measured using
different HD devices (PES, CNF1, CNF1-R) for (d) free-PC from
PBUT-side and (e) free-IS from PBUT-side; (f, g) Dialysis ratio at
pH 7.4, measured using different HD devices (PES, CNF1, CNF1-R) for
(f) PC from PBS-side and (g) IS from PBS-side; and
[0046] FIG. 14 Protein binding ratios determined using static CNF1
and CNF1-R device setups for the dissociation of PC and BSA. Inset:
Photograph of the static CNF1-R device setup in a two-electrode
configuration.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] Reference will now be made in detail to the exemplary
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. Therefore, it is to be
understood that the foregoing is illustrative of exemplary
embodiments and is not to be construed as limited to the specific
embodiments disclosed, and that modifications to the disclosed
exemplary embodiments, as well as other exemplary embodiments, are
intended to be included within the scope of the appended claims.
These embodiments are provided so that this invention will be
thorough and complete, and will fully convey the inventive concept
to those skilled in the art.
[0048] For convenience, certain terms employed in the
specification, examples and appended claims are collected here.
Unless defined otherwise, all technical and scientific terms used
herein have the same meaning as commonly understood by one of the
ordinary skill in the art to which this invention belongs.
[0049] Various embodiments will now be described more fully with
reference to the accompanying drawings, in which illustrative
embodiments are shown. The inventive concept, however, may be
embodied in various different forms, and should not be construed as
being limited only to the illustrated embodiments. Rather, these
embodiments are provided as examples, to convey the inventive
concept to one skilled in the art. Accordingly, known processes,
elements, and techniques are not described with respect to some of
the embodiments.
[0050] The following definition is applied in all disclosure of the
present invention. The weight percentage of all polymers, gels, and
other materials is represented by dry weight basis. The term
"polymer" means homopolymer or copolymer.
[0051] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting from the
standard deviation found in the respective testing measurements.
Also, as used herein, the term "about" generally means within 10%,
5%, 1%, or 0.5% of a given value or range. Alternatively, the term
"about" means within an acceptable standard error of the mean when
considered by one of ordinary skill in the art. Other than in the
operating/working examples, or unless otherwise expressly
specified, all of the numerical ranges, amounts, values and
percentages such as those for quantities of materials, durations of
times, temperatures, operating conditions, ratios of amounts, and
the likes thereof disclosed herein should be understood as modified
in all instances by the term "about." Accordingly, unless indicated
to the contrary, the numerical parameters set forth in the present
invention and attached claims are approximations that can vary as
desired. At the very least, each numerical parameter should at
least be construed in light of the number of reported significant
digits and by applying ordinary rounding techniques.
[0052] The singular forms "a", "and", and "the" are used herein to
include plural referents unless the context clearly dictates
otherwise.
[0053] "Wt. %" means the number of parts by weight of monomer per
100 parts by weight of polymer, or the number of parts by weight of
ingredient per 100 parts by weight of composition or material of
which the ingredient forms a part.
[0054] The following descriptions are provided to elucidate the
process of preparing an electrically conductive nanofiber mat for
purification blood and to aid it of skilled in the art in
practicing this invention. These Examples are merely exemplary
embodiments and in no way to be considered to limit the scope of
the invention in any manner.
[0055] Protein-bound uremic toxins (PBUTs) can cause noxious
effects in patients suffering from renal failure as a result of
inhibiting the transport of proteins and inducing their structural
modification; they are difficult to remove through standard
hemodialysis (HD) treatment. Herein, the present invention reports
an organic bioelectronic HD device system for the effective removal
of PBUTs through electrically triggered dissociation of
protein-bound substances, such as protein-bound toxin complexes. To
prepare this system, the present invention employed electrospinning
to fabricate electrically conductive quaternary composite nanofiber
mats-comprising multiwall carbon nanotubes (MWCNTs),
poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS),
poly(ethylene oxide) (PEO), and
(3-glycidyloxypropyl)trimethoxysilane (GOP S)--on conventional
polyethersulfone (PES) dialysis membranes. These composite
nanofiber platforms exhibited (i) long-term water-resistance (due
to crosslinking among PSS, PEO, and GOPS); (ii) high adhesion
strength on the PES membrane (due to GOPS functioning as an
adhesion promoter); (iii) enhanced electrical properties [due to
the MWCNTs and PEDOT:PSS promoting effective electrical stimulation
(ES) operation in devices containing bioelectronic interfaces
(BEI)]; and (iv) good anticoagulant ability and negligible
hemolysis of red blood cells. The present invention employed this
organic BEI electronic system as a novel single-membrane HD device
to study the removal efficiency of four kinds of the uremic toxins
[p-cresol (PC), indoxyl sulfate (IS), and hippuric acid (HA) as
PBUTs; creatinine (CRT) as a non-PBUT] as well as the effects of ES
on lowering the protein binding ratio. The organic BEI devices
provided a high rate of removal of PC with low protein loss after 4
h of a simulated dialysis process; it also functioned with low
complement activation, low contact activation levels, and lower
amounts of platelet adsorption, suggesting great suitability for
use in developing next-generation bioelectronic medicines for
HD.
Experimental Section
[0056] The following descriptions represent merely the exemplary
embodiment of the present invention, without any intention to limit
the scope of the present disclosure thereto. Various equivalent
changes, alternations or modifications, based on the claims of
present invention are all consequently viewed as being embraced by
the scope of the present invention.
Materials and Methods
[0057] MWCNT/PEDOT:PSS Nanofiber Mats. The electrically conductive
MWCNT/PEDOT:PSS nanofiber mats, prepared from a quaternary blend
solution of MWCNTs, PEDOT:PSS aqueous solution, poly(ethylene
oxide) (PEO) solution, and (3-glycidyloxypropyl)trimethoxysilane
(GOPS), were deposited through needle-type electrospinning (FIG.
1a). The PEDOT:PSS aqueous solution (Clevios PH1000; the ratio of
PEDOT and PSS is 1:2.5.about.1:6, preferably 1:2.5) was purchased
from H. C. Starck. Poly(ethylene oxide) (PEO; molecular weight:
900,000), (3-glycidoxypropyl)trimethoxysilane (GOPS), and multiwall
carbon nanotubes (MWCNTs; as-produced cathode deposit;
O.D..times.L: 7-15 nm.times.0.5-10 .mu.m) were obtained from
Sigma-Aldrich. PEO solution is ranged 5.about.30 wt % based on a
total weight of the quaternary blend solution. It should be noted
that PEO solution is merely an exemplary example in this
embodiment, other water-soluble polymer solutions also can be used
in the present invention, such as polyvinyl alcohol (PVA) solution,
polyethyleneimine (PEI) solution, poly(acrylic acid) (PAA)
solution, poly(styrenesulfonate) (PSS) solution,
Polyvinylpyrrolidone (PVP) solution, polyacrylamide (PAM) solution,
poly(ethyl exazoline) solution, poly-lysine solution,
poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide)
(PPO-PEO-PPO) triblock copolymers solution, poly(ethylene
oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO)
triblock copolymer solution, an alginate solution, hyaluronic acid
(HA) solution, a gelatin solution, a collagen solution,
polyglutamic acid (PGA) solution, a chitin solution, a chitosan
solution, a cellulose solution or a combination thereof. The
following electrospinning parameters were applied: (a) a 27-gauge
disposable needle was used as the anode for electrospinning (from
the Taylor cone of polymer solutions) with a flow rate of 1 mL
h.sup.-1 and a voltage supply of 22 kV; (b) the distance between
the collecting polyethersulfone (PES) dialysis membrane (EMD
Millipore; molecular weight cut-off: 30 kDa) and the needle tip was
11 cm; (c) the polymer blend solutions were electrospun in an
atmosphere of air for 10 min at ambient temperature under a
relative humidity of less than 45%; (d) an air blower was employed
to prevent the nanofibers from standing up during the whole
electrospinning process. Finally, thermal cross-linking treatment
(80.degree. C..about.150.degree. C., preferably 130.degree. C. for
at least 1 h) of the MWCNT/PEDOT:PSS nanofiber mats, ensuring
cross-linking of the PSS, PEO, and GOPS materials, was applied to
enhance the wet-stability. It should be noted that a conventional
crosslinking agent may be used in the present invention, but not
limited to GOPS. The MWCNT/PEDOT:PSS nanofiber mats incorporating
0, 1, 2, 3, 4 and 5 wt % of the MWCNTs are named herein NF, CNF1,
CNF2, CNF3, CNF4, and CNF5, respectively.
[0058] Characterization of Nanofiber Mats. Raman spectra in the
range 400-3500 cm.sup.-1 were recorded using a Raman spectrometer
(HR800, HORIBA, Japan) and a 17-mW-output helium-neon (He--Ne)
laser operated at a wavelength of 633 nm. Field-emission scanning
electron microscopy (FE-SEM, JEOL JSM-6701F, Japan) images of the
MWCNT/PEDOT:PSS nanofiber mats were obtained after they had been
dehydrated and sputter-coated with platinum (<3 nm); the
accelerating voltage was 15 kV. Transmission electron microscopy
(TEM, JEOL 2010, Japan) images of the MWCNT/PEDOT:PSS nanofiber
mats were obtained at 200 kV. Cross-cut adhesion tests of the
MWCNT/PEDOT:PSS nanofiber mats on PES substrates were performed
using a cross-cut tester (ZCC 2087, Zehntner, Switzerland) in
accordance with the ASTM D3359 standard.
[0059] Blood Clotting Times, Hemolytic Assays, and Platelet
Adhesion Tests. Human blood stabilized with
ethylenediaminetetraacetic acid (EDTA) was collected and then
centrifuged to obtain the targeted liquid biopsy. Centrifugation
for 15 min at 4000 rpm was used to obtain platelet-poor plasma
(PPP); centrifugation for 15 min at 1000 rpm was used to obtain
platelet-rich plasma (PRP); red blood cells (RBCs) were obtained by
centrifuging for 10 min at 2000 rpm, removing the upper clear serum
solution, and washing five times with 1.times. phosphate buffer
saline (PBS). To evaluate the anti-thrombogenicity of the
MWCNT/PEDOT:PSS nanofiber mats coated PES membranes, the test
samples were cut into pieces (1.times.1 cm.sup.2), incubated in PPP
(0.5 mL) at 37.degree. C. for 1 h, and then the anti-coagulation
properties were determined through a clotting assay, where the
coagulation pathways were monitored in terms of Factor XII of
activated partial thromboplastin time (APTT, related to the
intrinsic and common pathway of coagulation) and Factor VII of
prothrombin time (PT, related to the extrinsic pathway of
coagulation), measured using an automated blood coagulation
analyzer (CA-50, Sysmex, Japan). The positive and negative controls
for clotting time measurement were tested against an untreated
tissue culture polystyrene (TCPS) dish and PPP without any sample
added, respectively. For hemolytic assays, the diluted RBCs were
prepared by diluting (1:10) the RBC suspension with PBS. Portions
of the diluted RBC suspension (0.2 mL) were then treated with 0.8
mL of DI water (as positive control) or PBS buffer (as negative
control). NF and CNF1 (2 mg) were incubated in the negative-control
RBC suspension (1.0 mL) at 37.degree. C. for 2 h, followed by
centrifugation for 2 min at 10,000 rpm. Finally, the supernatant
was subjected to UV-Vis spectrometry (V570, Jasco, Japan) to
calculate the hemolytic percentage, based on its absorbance at 540
nm. The hemolytic percentage was calculated by dividing the free
hemoglobin concentration in blood by the total hemoglobin
concentration of each separate sample. For the platelet adhesion
tests, samples (1.times.1 cm.sup.2) were pre-incubated in PBS
buffer at 37.degree. C. for 1 h, then transferred into as-prepared
PRP (1 mL; the platelet count in PRP was adjusted to
3.times.10.sup.8 mL using PBS buffer) and incubated at 37.degree.
C. for 2 h. The PRP was aspirated and samples washed three times
with PBS buffer. Finally, for fluorescence imaging, the samples
were subjected to staining process with calcein acetoxymethyl ester
(calcein-AM, 4 M) for 10 min at 37.degree. C. Prior to SEM imaging
of platelet adhesion on the PES membranes, the PRP-adhered samples
were fixed with 4% paraformaldehyde for 20 min and then dehydrated
in ascending grades of EtOH (25, 50, 75, and 100%; each dehydration
time: 20 min) with freeze-drying.
[0060] Electrical Characterization of MWCNT/PEDOT:PSS Films and
Nanofibers. The electrical conductivities of the MWCNT/PEDOT:PSS
films were measured using a Keithley 2400 source meter and a
four-point probe. To measure the electrical conductivity of single
electrospun fibers, MWCNT/PEDOT:PSS nanofibers were first
electrospun onto Au interdigitated electrodes (IDEs) prepared on a
glass substrate (Dropsens: DRP-G-IDEAU10). A
potentiostat/galvanostat (PGSTAT320N, Autolab, Netherlands) and a
frequency response analysis (FRA) module were used to determine the
resistance between the two finger electrodes of the IDEs in a
two-electrode configuration. The contact resistance was subtracted
from the total resistance to determine the electrical conductivity
of the MWCNT/PEDOT:PSS nanofiber, according to a previously
reported procedure. CV and EIS were performed using a
potentiostat/galvanostat with a FRA module in a three-electrode
configuration in a glass cell. A Pt wire and a Ag/AgCl electrode
were used as the counter electrode (CE) and reference electrodes
(RE), respectively. CV measurements were performed in PBS over the
potential range from -0.8 to +0.8 V at sweep rate of 100 mV
s.sup.-1. EIS measurements were performed in PBS by applying an AC
voltage (amplitude: 5 mV) in the frequency range from 10.sup.-1 to
10.sup.5 Hz. Electrokinetical analysis (Zeta potential) of
MWCNT/PEDOT:PSS nanofibers was performed using a SurPASS
electrokinetic analyzer (Anton Paar, Australia) with two Ag/AgCl
electrodes; the measurements were performed (pH range from 2 to 9)
using a streaming current method with 0.001 M KCl as the
electrolyte solution; the pH was adjusted to 7.4 by adding either
0.05 M HCl or 0.05 M NaOH.
[0061] XPS Measurement. XPS spectra were recorded using a PHI 5000
VersaProbe system (ULVAC-PHI, Japan) and microfocused (100 .mu.m,
25 W) Al K.alpha. X-rays with a photoelectron takeoff angle of
45.degree.. The nanofiber mats were electrospun on PES membranes
for transfer into the system for direct analysis. During spectral
acquisition, a dual-beam charge neutralizer (7-V Ar.sup.+beam and
1-V flooding-electron beam) was used to compensate the charge-up
effect.
[0062] Simulated Dialysis Experiments. In the dialysis device, a
dialysis membrane having an effective area of 3.3 cm.sup.2 was
designed for division between two separate internal circulation
compartments; one internal circulation flow used 50 mL of the PBUT
solution and the other used 50 mL of PBS buffer. The flow rates of
the solution reservoir (with the uremic toxin) and PBS buffer
reservoir were each 50 mL min.sup.-1. The temperature of the
circulation flow was maintained at 37.degree. C. using a water
bath; samples (1 mL) were collected from the solution and PBS
reservoirs at 1-h intervals over a period of 4 h; the experiments
were repeated at least three times. Prior to the dialysis
experiment, a washing procedure was applied using PBS buffer at
37.degree. C. for 3 h. The changes in the concentrations of four
uremic toxins [p-cresol (PC), indoxyl sulfate (IS), hippuric acid
(HA), and creatinine (CRT)] were measured (UV-Vis
spectrophotometer) at 277, 278, 229, and 232 nm, respectively. The
removal efficiencies of these four uremic toxins were calculated
using Eq. (1):
Removal efficiency ( % ) = C 0 - C t C 0 .times. 100 % ( 1 )
##EQU00001##
where C.sub.0 and C.sub.t are the uremic toxin concentrations in
the solution reservoir initially and at time t (1, 2, 3, or 4 h),
respectively. The concentration of BSA was determined through a
Bradford protein assay using a UV-Vis spectrophotometer with
monitoring at 595 nm. The BSA retention percentage was calculated
using Eq. (2):
Retention percentage ( % ) = C t C 0 .times. 100 % ( 2 )
##EQU00002##
where C.sub.0 and C.sub.t are the BSA concentrations in the
solution reservoir initially and at time t (1, 2, 3, or 4 h),
respectively. For the dialysis experiment of PBUT pre-bonded BSA
solution, 50 ppm of targeted uremic toxins were mixed with various
amount of BSA (4, 20, and 40 g L.sup.-1) and shaken for 24 h at
37.degree. C. Collected samples (1 mL) were purified through
centrifugation (12,000.times.g, 25.degree. C., 5 min) using a
Vivaspin centrifuge (Vivaspin 2, 30 kDa cutoff, GE Healthcare); the
PBUTs were separated into the bottom device, thereby collecting BSA
proteins from the top device. The MWCNT/PEDOT:PSS nanofiber devices
were operated in a two-electrode setup consisting of a working
electrode (WE; ITO glass coated with PEDOT-based nanofibers) and a
CE (Ag/AgCl electrode), which was connected to the RE. CV sweeping
over the potential range from -3 to +3 V, preferably -0.8 to +0.8 V
(sweep rate: 100 mV s.sup.-1) was used as ES to electrically
eliminate the electrostatic bonding between the PBUT and BSA.
[0063] Cell Viability Test. The human monocytic leukemia cell line
THP1 was purchased from the Bioresource Collection and Research
Center (BCRC, Taiwan). Fetal bovine serum (FBS) was purchased from
HyClone. RPMI 1640 growth medium were purchased from Invitrogen.
THP1 cells were cultured in RPMI 1640 medium supplemented with 10%
FBS and maintained at 5.times.10.sup.5 cells mL.sup.-1. THP1 cell
suspensions (50 mL) in a cell culture medium (2.times.10.sup.6
cells mL.sup.-1) were prepared and filled into the solution
reservoir; the cell viabilities and cell counts were monitored
during 4 h of dialysis treatment, using a Luna.TM. automatic cell
counter (Logos Biosystems, South Korea).
Results and Discussion
[0064] Ideally, it would be useful to remove PBUTs from patients
through HD, but because of their electrostatic interactions with
the solute and proteins, it is difficult for them to penetrate
through the dialysis membrane during standard HD treatment. The
present invention has developed a novel bioelectronic device
integrated with electrically conductive MWCNT/PEDOT:PSS nanofiber
mats for advanced blood purification. Based on a electrospinning
methodology, a quaternary blend--an aqueous solution of MWCNTs,
PEDOT:PSS, PEO, and GOPS--was deposited in the form of nanofibers
onto a PES dialysis membrane. PEDOT:PSS (PH1000) was demonstrated
readily covered the surfaces of MWCNTs after dispersing them in an
aqueous PEDOT:PSS solution and applying high-power probe
ultrasonication (20 kHz, 700 W), thereby stabilizing up to 10 wt %
of the dispersion of MWCNTs. Furthermore, the crosslinking
reactions that occur in a ternary mixture of PEO, PEDOT:PSS, and
GOPS also improve the long-term water resistance of
PEO/PEDOT:PSS-based nanofibers. The present invention found that
using 5.about.30 wt %, preferably 15 wt %, PEO solution as
additives based on a total weight of the quaternary blend solution,
and using 1.about.10 wt %, preferably 3 wt % GOPS, based on total
weight of the PEDOT:PSS solution not only resulted in excellent
spinnability during the electrospinning process but also provided a
promising approach for enhancing the fibers' mechanical stability
and adhesion to the substrate. Therefore, in the present invention,
based on the above formula ratio of PEO and GOPS in PEDOT:PSS
suspensions, the effect of incorporating various contents (0, 1, 2,
3, 4, 5 wt %) of MWCNTs was tested with the goal of developing
suitable BEI-based HD devices for PES dialysis membranes. Because
the addition of 1 wt % dimethylsulfoxide (DMSO) in MWCNT/PEDOT:PSS
solutions led to poor spinnability, here the present invention
investigated the electrospinning parameters, the morphologies, and
the dimensional and adhesion properties of MWCNT/PEDOT:PSS
nanofiber mats prepared without DMSO doping (Table 1). The
priorities for the nanofiber mats to be used in HD applications
were low degrees of delamination and two-dimensional (2D) thin film
morphologies. The present invention found in this series of
experiments that a MWCNT content of less than 3 wt % in the
MWCNT/PEDOT:PSS solutions converted the morphology from a
three-dimensional (3D) fiber stack to 2D mats; therefore, The
present invention prepared four different samples (NF, CNF1, CNF2,
CNF3) to explore all of the possibilities of using nanofiber mats
as BEIs in the present invention for the development of
next-generation HD devices.
TABLE-US-00001 TABLE 1 Electrospinning parameters, morphology, and
dimensional and adhesion properties of MWCNT/PEDOT:PSS nanofibers
on PES membranes. Flow Applied Fiber Adhesion rate voltage Humidity
Mor- diameter .sup.a strength .sup.b Sample (mL h.sup.-1) (kV) (%)
phology (d, nm) (Level) NF 1 22 <45 2D mats 142 .+-. 68 5B CNF1
1 22 <45 2D mats 157 .+-. 65 4B CNF2 1 22 <45 2D mats 121
.+-. 60 3B CNF3 1 22 <45 2D mats 106 .+-. 49 1B CNF4 1.4 23
<45 3D fiber -- N/A stacks CNF5 0.9 24 <45 3D fiber -- N/A
stacks .sup.a This value was obtained from the SEM image of
nanofibers (N = 50). .sup.b This classification of adhesion
strength was evaluated according to ASTM D3359.
[0065] To examine the compositions of the electrospun
MWCNT/PEDOT:PSS nanofiber mats, the Raman spectra of NF, CNF1,
CNF2, and CNF3 after laser excitation was recorded at a wavelength
of 633 nm (FIG. 1b). The Raman signals of the MWCNTs, corresponding
the D, and 2D bands (indicated by circles), appeared at 1336, 1567,
and 2683 cm.sup.-1, respectively; the Raman signal of the
PEDOT:PSS, corresponding to the ring C.dbd.C stretching vibrations
for PEDOT (indicated by a triangle), appeared at 1425 cm.sup.-1;
the Raman signal of the PEO, representing C--H stretching
(indicated by a rhombus), appeared at 2892 cm.sup.-1. As expected,
these characteristic signals in the spectra of NF, CNF1, CNF2, and
CNF3 were consistent with their compositions of PEDOT, PEO, and
MWCNTs in the electrospun nanofiber mats. Next, SEM was used to
observe the morphologies of all of the MWCNT/PEDOT:PSS nanofiber
mats on HD membranes; the corresponding diameter distributions were
calculated through image analysis using ImageJ software (FIG. 2).
The nanofibers in samples NF and CNF1 featured relatively similar
diameter distributions (ca. 150 nm), whereas the nanofiber
structures in CNF1 were composed of entangled MWCNTs (FIGS. 2a and
2b). When the content of MWCNTs was increased from CNF1 to CNF2 and
CNF3, the nanofiber populations shifted to smaller diameters--from
157.+-.65 nm to 121.+-.60 and 106.+-.49 nm,
respectively--suggesting that stronger elongation forces, due to
greater repulsion of charges on the PEDOT:PSS-wrapped MWCNTs at
higher solid contents, were imposed upon the jet, thereby resulting
in smaller fiber diameters (FIGS. 2b-d and 2f-h).
[0066] Prior to studying the HD applications under ES, the present
invention has assembled a stacked bar chart of five-component
mixtures (MWCNT, PSS, PEDOT, GOPS, PEO) for each nanofiber mat
(FIG. 3a). According to the information provided with the
commercial PEDOT:PSS solution (CLEVIOS PH1000:1 wt % in water;
PEDOT:PSS ratio=1 2.5.about.1 6, preferably 1:2.5), if GOPS had not
evaporated during the fabrication process, the sample NF would
comprise 8.1 wt % PSS, 6.5 wt % PEDOT, 39.2 wt % GOPS, and 46.2 wt
% in the form of electrospun nanofiber mats; CNF1 would comprise
11.6 wt % MWCNTs, 7.1 wt % PSS, 5.7 wt % PEDOT, 34.7 wt % GOPS, and
40.9 wt % in the form of nanofiber structures; CNF2 would comprise
20.8 wt % MWCNTs, 6.3 wt % PSS, 5.0 wt % PEDOT, 31.2 wt % GOPS, and
36.7 wt % in the form of nanofiber structures; and CNF3 would
comprise 28.3 wt % MWCNTs, 5.6 wt % PSS, 4.5 wt % PEDOT, 28.3 wt %
GOPS, and 33.3 wt % in the form of nanofiber structures. a
four-point probe method has been applied to measure the electrical
conductivities of all of the 2D thin film electrodes, which are
presented with respect to the MWCNT contents in PEO/PEDOT:PSS
solutions (FIG. 3b). 100-nm-thick BEI thin films (NF, CNF1, CNF2,
CNF3) were prepared through spin-coating onto a glass substrate;
the corresponding measured electrical conductivities were
3.09.times.10.sup.-5, 0.16, 1.12, and 6.10 S cm.sup.-1,
respectively. Because of the incorporation of 11.6, 20.8, and 28.3
wt % MWCNTs in the PEO/PEDOT:PSS films, the conductivities of the
CNF1, CNF2, and CNF3 thin films was approximately four, five, and
six orders of magnitude higher, respectively, than that of the
pristine PEO/PEDOT:PSS film (NF). In addition to the conductivity
measurements using a linear arrangement of four-point probes on 2D
thin films, a potentiostat/galvanostat was also used with an FRA
module to measure the conductivity of one-dimensional (1D)
PEDOT-based electrospun nanofibers using two finger electrodes of
an interdigitated electrodes (IDEs) setup (FIG. 3c), according to
the previously reported procedure; the IDE measurements revealed
that the 1D nanofiber structure of MWCNT/PEDOT:PSS led to a linear
enhancement in the electrical conductivity upon increasing the
MWCNT content, but it was one order of magnitude lower than the
conductivity of the 2D thin film of the same composition.
[0067] To demonstrate the device concept of using a single membrane
of MWCNT/PEDOT:PSS nanofiber mats operated under ES, a standard
three-electrode system and 1.times.PBS buffer were used to examine
the CV and EIS curves of the various MWCNT/PEDOT:PSS nanofiber mats
on ITO (FIGS. 3d and 3e). As displayed in FIG. 3d, the charge
capacity density (CCD) differences of the MWCNT/PEDOT:PSS nanofiber
mats NF, CNF1, CNF2, and CNF3 obtained from the CV analysis (CV
sweeping voltage from -0.8 to +0.8 V) were 0.23, 0.59, 1.29, and
1.88 mC cm.sup.2, respectively; furthermore, the present invention
found that they were more efficient at forming reduced and oxidized
states to electrically eliminate the electrostatic bonding between
the PBUTs and BSA, relative to the CCD of ITO electrodes (0.06 mC
cm.sup.2). Furthermore, FIG. 3e presents the results of EIS
analysis of all of the BEI electrodes in the frequency range from
10.sup.-1 to 10.sup.5 Hz. The EIS impedance of the MWCNT/PEDOT:PSS
nanofiber mats, at frequencies below 100 Hz, decreased upon
increasing the MWCNT content, indicating that a high MWCNT content
in the PEO/PEDOT:PSS matrix would readily undergo a
doping/de-doping process and/or cause ionic exchange in the
low-frequency range of ES operation.
[0068] Using the thermal crosslinking process that the present
invention had employed previously for PEO/PEDOT:PSS nanofibers,
here those thermal annealing conditions were applied to the
MWCNT/PEDOT:PSS nanofiber mats deposited on the PES membranes (NF,
CNF1, CNF2, CNF3) at 130.degree. C. for 6 h, followed by PBS buffer
treatment for 24 h (FIG. 4). The photographs of all of the samples
in FIGS. 4a-d revealed a uniform coating of nanofiber mats on the
PES membranes, with no apparent curling, after thermal treatment.
In addition, SEM images revealed that the annealed PEDOT-based
nanofibers remained intact after the long-term treatment with the
PBS solution, confirming the excellent dimensional stability of the
nanofibers and their water-resistance (FIGS. 4e-1). FIGS. 4m-p
display TEM images revealing the different morphologies of the
MWCNT/PEDOT:PSS nanofiber mats containing the various MWCNT
contents. In the absence of the MWCNTs in the nanofiber mats (NF),
the PEO/PEDOT:PSS formed core/shell nanofiber structures having the
geometrical shapes (comprising a rough, darker, PEDOT-rich
nanofiber core enclosed within a thin, brighter, PSS-rich layer).
Upon increasing the content of MWCNTs, the nanofiber structures
featured more MWCNTs entangled in the electrospun nanofiber and
featured more pop-up structures of MWCNTs.
[0069] To evaluate the adhesion strengths of the MWCNT/PEDOT:PSS
nanofiber mat coatings over the PES membranes, the present
invention conducted cross-cut adhesive tape tests of the nanofiber
mat-coated surfaces, using the standard American standard test
method (ASTM) according to ASTM D3359 (FIG. 5). No peeling of the
NF coating from the PES surface was evident under an optical
microscope, suggesting that its adhesion level reached 5B. Upon
increasing the content of MWCNTs, however, the adhesion level of
the electrospun MWCNT/PEDOT:PSS nanofiber mat coatings worsened:
from a 4B index for the CNF1 coating, down to a 3B index for the
CNF2 coating and 1B index for the CNF3 coating. Indeed, the present
invention found that higher contents of MWCNTs in the PEDOT:PSS
matrix resulted in a much weaker bonding between the nanofiber mat
and the PES membrane, thereby significantly decreasing the adhesion
strength and lessening the potential for operation of HD treatment
under continuous flow conditions.
[0070] As a material design concept for developing anti-coagulant
membranes for advanced HD devices, the MWCNT/PEDOT:PSS nanofiber
mats coated membranes were inspired by the heparin polymer (due to
the presence of sulfonic acid groups in PSS), which has been the
most commonly used antithrombin-binding domain for preventing blood
coagulation and thrombus formation during HD treatment. As
displayed in FIGS. 6a and 6b, the present invention used the blood
clotting times of APTT and PT in the intrinsic and extrinsic
pathways, respectively, to evaluate the anti-thrombogenicity of NF,
CNF1, CNF2, and CNF3 relative to those of the positive control of
an untreated TCPS dish and the negative control of PPP without any
sample added. As expected, all of PEDOT-based nanofiber mats coated
membranes provided increased blood clotting times for APTT and TT,
presumably because of the sulfonic acid groups of the
heparin-mimicking polymer PSS or the antifouling performance of the
PEO domains on the nanofiber surfaces, thereby enhancing
anticoagulation activity to avoid thrombus formation. CNF1 provided
the largest clotting times for APTT and TT of 49.8 and 17.0 s,
respectively, compared with the negative control of PPP (36.0 s for
APTT; 10.1 s for TT). The present invention found that a high
degree of MWCNT doping in the nanofiber mats did not have a strong
influence on the clotting time, suggesting that most of the MWCNTs
were covered well by a thin layer of PEDOT:PSS, as we had also
observed previously for MWCNT/PEDOT:PSS scaffolds. Furthermore, the
present invention confirmed the hemocompatibility of the NF and
CNF1 fiber samples by using a UV-Vis spectroscopic method to
quantify (FIG. 6c) the difference in absorbance of the supernatant
at 540 nm after exposure to a suspension of RBCs, associated with
the positive control (exposed to DI water to attain 100%
hemolysis). When compared with the observations in the inset to
FIG. 6c, the absence of CNF1 in the RBC suspension did not result
in any obvious hemolytic effect (a hemolytic percentage of ca. 3%)
when compared with the negative control (exposed to PBS), whereas
the NF fiber sample caused slight hemolysis with a hemolytic
percentage of less than 9%. When investigating the blood clotting
and hemolytic effects of using MWCNT/PEDOT:PSS nanofiber mats,
streaming potential measurements can provide information about the
surface charge (zeta potential) and the isoelectric point of
as-prepared samples. As displayed in FIG. 6d, all of the nanofiber
mats (NF, CNF1, CNF2, CNF3) possessed negative zeta potentials over
the wide pH range from 2 to 9. Notably, decreasing the PSS content
(from 8.1% in NF to 7.1, 6.3, and 5.6% in CNF1, CNF2, and CNF3,
respectively) in the PEDOT-based nanofiber structures (FIG. 3a) led
to a slight increase in the zeta potential on the nanofiber mats at
pH 7 (from 26.5 mV for NF to -20.4 mV for CNF1, -17.5 mV for CNF2,
and -11.4 mV for CNF3). As these results indicate, the zeta
potentials of the MWCNT/PEDOT:PSS nanofiber mats were close to that
of the anticoagulant heparin (-39 mV) and the negatively charged
RBCs (-17 mV), thereby providing the expected good anti-coagulant
performance and hemocompatibility.
[0071] In addition the evaluations of blood clotting times by using
the PPP test, the number of adherent platelets is another indicator
that can be related to the anti-coagulant performance of
PRP-adhered samples. To better visualize the small platelets (1.5-3
m) on the opaque MWCNT/PEDOT:PSS nanofiber mats, the present
invention performed calcein-AM staining to investigate the green
fluorescence images of the metabolic activity of the platelets. As
displayed in FIG. 7, the numbers of adhered metabolically active
platelets on all of the nanofiber mats (NF, CNF1, CNF2, CNF3) were
much lower than those on indium tin oxide (ITO) glass and TCPS,
suggesting that the lower amount of adherent platelets would
directly decrease the possibility of releasing the many clotting
factors that work together in a series of complex chemical
reactions, thereby reducing the risk of dialysis membrane failure
arising from coagulation.
[0072] To further investigate the effects of surface chemistry on
the platelet morphologies on top of the PEDOT:PSS nanofiber mats,
XPS was used to obtain high-resolution core-level spectra (S.sub.2)
of NF, CNF1, CNF2, and CNF3 and then determined the changes in the
PSS/PEDOT ratio in the surface composition when blending different
weight percentages of MWCNTs in the PEO/PEDOT:PSS matrix, while
also obtaining information about the phase separation of the PEDOT
and PSS chains on the MWCNT/PEDOT:PSS nanofibers at the molecular
level (FIG. 8, Table 2). Applying the same analysis method used for
PEDOT:PSS materials, deconvolution of the XPS S.sub.2p core-level
spectra allowed us to measure changes in the PSS/PEDOT composition
ratio in these quaternary composite nanofiber systems. From the
comprehensive assessment of PSS and PEDOT chains (with the
corresponding set of S 4.sub.3/2 and S 2p.sub.1/2 peaks), the
PSS/PEDOT ratio of 1.71 for the NF increased dramatically to 2.23,
2.03, and 2.70 for CNF1, CNF2, and CNF3, respectively, signifying
that some of heparin-like PSS polymers had been phase-separated to
the surface of the nanofibers, thereby leading to a significant
decrease in the degree of platelet adhesion.
TABLE-US-00002 TABLE 2 The atomic percentages of PSS and PEDOT and
PSS/PEDOT ratios (from peak deconvolution of XPS S.sub.2p data) of
MWCNT/PEDOT:PSS nanofiber mats. At. % from XPS (S.sub.2p) data PSS
PSS PEDOT PEDOT PSS/PEDOT Sample 2p.sub.1/2 2p.sub.3/2 2p.sub.1/2
2p.sub.3/2 ratio NF 19 46 27 8 1.71 CNF1 12 57 12 19 2.23 CNF2 21
46 15 18 2.03 CNF3 33 40 16 11 2.70
[0073] Taking together the electrical properties, the adhesion
strengths, the anticoagulant abilities, and the hemocompatibility,
the present invention concluded that the CNF1 mats over the PES
membranes exhibited the optimized performance for subsequent use in
HD applications. In this proof-of-concept embodiment, the present
invention first deposited the CNF1 mats and Ag/AgCl electrodes
(Ag/AgCl Ink, ALS) over a PES membrane (molecular weight cut-off:
30 kDa) to form a CNF1-based HD device, and then assembled this
membrane filter into a lab-scale single-membrane dialysis system
(FIG. 9a), where the dialysis membrane with an effective area of
3.3 cm.sup.2 was designed to be divided between two separate
internal circulation compartments. As displayed in FIG. 9b, one
internal circulation flow was pumped from a reservoir containing 50
mL of the specific PBUT solution (denoted as PBUT-side buffer) and
passed through the left-hand side of the membrane filter (green
line); another internal circulation flow was pumped from another
reservoir containing 50 mL of PBS buffer solution (denoted as
PBS-side buffer) and passed through the right-hand side of the
membrane filter (yellow line); the flow rates of all solutions were
kept at 50 mL min.sup.-1 by using alternate opposite flow
directions across the dialysis membrane. PEDOT:PSS conductive
polymers exhibit promising properties as pseudocapacitor materials,
meaning that charge transfer, enhanced adsorption, pH changes, and
redox reactions can be facilitated near the surfaces of PEDOT:PSS
nanofibers in the electrolyte. Because of the possible
electrostatic interactions between the PBUTs and proteins, the
present invention wanted to leverage such PEDOT:PSS behavior, using
CNF1, to enhance the rejection rate of BSA and decrease the
protein-bound fraction of the PBUTs under ES operation, which may
feature four sequential steps: Step 1--the BSA-bound PBUT exhibits
a negative charge at pH 7.4 and disperses in the PBUT-side; Step
2--the CNF1 device provides an electrostatic attractive force to
promote the adsorption of net negatively charged BSA proteins on
the surface under the ES operation (between 0 and 3 V, preferably
between 0 and +0.8 V); Step 3--the CNF1 device electrically
eliminates the electrostatic bonding between the PBUT and BSA upon
CV sweeping (between -3 and +3 V, preferably between -0.8 and +0.8
V), thereby improving the clearance rate of the PBUTs; Step 4--the
CNF1 device provides an electrostatic repulsion force to increase
BSA retention in the PBUT-side during ES operation (between -3 and
0 V, preferably between -0.8 and 0 V) (FIG. 9c). FIGS. 9d and 9e
present photographs of experimental setup for the organic
bioelectronic HD device (with a two-electrode device system); it
was connected through a peristaltic pump that controlled the flow
rates of the PBUT- and PBS-side buffers; all reservoirs were
maintained in a water bath at 37.degree. C. To confirm that the ES
potential would not result in a sharp decrease in cell viability,
the present invention conducted a trypan blue dye exclusion assay
to evaluate the system's biocompatibility for THP1 leukemia cells
(a type of white blood cell line) during 4 h of simulated dialysis
treatment. The cell viability test results confirmed that this
demonstration of CNF1-based HD devices, under 4 h of ES operation
(CV sweeping between -3 and +3V, preferably between -0.8 and +0.8 V
at a scan rate of 100 mV s.sup.-1), could preserve the good
biocompatibility, with cell viability of greater than 90% (FIG.
9f).
[0074] It should be noted that the dialysis membrane is
conventional and further comprises cellulose triacetate (CTA)
membrane, ethylene vinyl alcohol (EVAL) membrane, polyacrylonitrile
(PAN) membrane, polyester polymer alloy (PEPA) membrane,
polymethylmethacrylate (PMMA) membrane, polysulfone (PS) membrane,
a regenerated cellulose (RC) membrane, or a cellulose diacetate
(CDA) membrane, besides PES membrane.
[0075] It also should be noted that CE and RE are conventional and
further comprises silver(Ag) electrode, gold(Au) electrode,
platinum (Pt) electrode, iridium (Ir) electrode, Pt/Ir alloy
electrode, iridium oxide electrode, titanium (Ti) electrode, or
titanium nitride (TiN) electrode, besides Ag/AgCl electrode.
[0076] To examine the true impact on HD applications when using the
CNF1 mats, the present invention developed a novel organic BEI
electronic system as the single-membrane HD device to further study
the clearance rate of four different uremic toxins: three kinds of
PBUTs (PC, IS, HA) and one kind of small-molecule non-PBUT (CRT);
the chemical structures and physicochemical properties of these
uremic toxins are summarized in FIGS. 10a and 10b. The
physicochemical properties of PC, IS, HA, and CRT were calculated
using MarvinSketch 6.2.2 (ChemAxon Kft., Budapest, Hungary). The
polar surface area (PSA), reflecting the molecular weight of uremic
toxins, decreased in the order IS (79.39 .ANG..sup.2), HA (66.40
.ANG..sup.2), CRT (56.19 .ANG..sup.2), and PC (20.23 .ANG..sup.2);
the net charge at pH 7.4, reflecting the different chemical
structures of the uremic toxins, decreased in the order CRT
(+0.03)>PC (-0.01)>IS (-0.89)>HA (-0.99)--the net charges
of CRT and PC were almost zero, suggesting minimal electrostatic
interactions. To optimize the CNF1-based devices for HD treatment,
the present invention first explored the influence of the
electrospinning time (0, 5, 10, 20 min) of CNF1 on the dialysis
performance (clearance rate and dialysis ratio) for the removal of
PC uremic toxins, where the sum of "clearance rate" and "relative
ratio" for the uremic toxin was 100%. In FIGS. 10c and 10d,
although the PES membrane (0 min of electrospinning time) exhibited
a higher removal efficiency for PC [relative ratio (48.8%) in
PBUT-side; clearance rate (51.2%) in PBUT-side; dialysis ratio
(3.4%) in PBS-side] than those of all the CNF1 samples, the
electrically conductive CNF1 could possibly introduce an additional
function: minimizing the protein binding fraction with the PBUTs,
due to the elimination of electrostatic interactions between the
PBUTs and proteins during ES operation. Therefore, when considering
the possibility of BEI-based HD devices, 10 min of electrospinning
of CNF1 could provide the optimized removal efficiency for PC
[relative ratio (47.8%) in PBUT-side; clearance rate (52.2%) in
PBUT-side; dialysis ratio (1.7%) in PBS-side] after dialysis for 4
h. As displayed in FIGS. 10e-g, the PES membrane and CNF1 provided
a much higher clearance rate (lower uremic solute content) for PC
than for IS, HA, and CRT, due to the inherently stronger adsorption
capacity of PC [e.g., stronger .pi.-.pi. interactions, weaker
negative-negative electrostatic repulsive interactions];
nevertheless, the present invention observed similar dialysis
ratios (ca. 1.2-4.4%) for all of the solutes because of the small
effective dialysis area of 3.3 cm.sup.2.
[0077] Prior to studying the ES effect on the weakening of PBUT
binding to proteins, the present invention first conducted a 4-h CV
sweeping to investigate the long-term stability of the CNF1-based
HD devices; this stability was dependent on the reversibility of
the redox behavior of CNF1 during the dialysis process (FIG. 11).
FIGS. 11 a-c present the current densities during ES operation (CV
sweeping between -3 and +3V, preferably between -0.8 and +0.8 V at
a scan rate of 100 mV s.sup.-1) in the as-prepared PC solution (50
ppm), IS solution (50 ppm), and PBS buffer, respectively, for
CNF1-based HD devices having an effective area of 3.3 cm.sup.2. In
FIGS. 11a and 11e-i, the CV curves exhibit a gradual decay in the
current density range (.DELTA.J) from 0.080 to 0.071, 0.069, 0.065,
and 0.057 mA cm.sup.-2 during ES operation from 0 to 1, 2, 3, and 4
h, respectively. There was a decreasing trend in the value of Al in
PBS buffer under long-term ES operation, suggesting that the
changed ratio of current density appeared to decrease (-28.5% for
PC treatment; -26.4% for PBS treatment) because the trapped ions
within CNF1 suppressed the ionic transport (FIGS. 11a, 11c, and
11d); nevertheless, FIGS. 11b and 11d reveal that treatment with
the IS solution led to an increasing trend in the value of Al,
suggesting that the changed ratio of current density appeared to
increase from 0 to +69.4% for CNF1, possibly because of the
selective removal of insulating PSS or an increase in the doping
level upon treatment with the IS solution.
[0078] The results reflected that the CNF1-based HD devices could
provide the long-term stability of ES operation during 4 h of
dialysis. Considering the normal concentration range of serum
albumin (1-50 g L.sup.-1), the present invention performed
comprehensive protein binding ratio studies using 50 ppm of PC, IS,
HA, and CRT uremic toxins in the presence of various amounts of BSA
(4, 20, and 40 g L.sup.-1) through centrifugal ultrafiltration
(with a 30-kDa-cutoff membrane). FIG. 12 reveals that most of the
CRT uremic toxin was free, meaning that the extremely low protein
binding ratio of 1.0-2.1% could be attributed to the Vivaspin 2
device with a recovery performance of greater than 97.9%;
nevertheless, PC was more strongly bound to BSA (estimated
protein-binding ratio: 89.4-94.4%) than were IS (estimated
protein-binding ratio: 31.3-74.1%) and HA (estimated
protein-binding ratio: 18.3-36.9%) in the concentration range of
BSA (4-40 g L.sup.-1 in PBS buffer). Because 4 g L.sup.-1 BSA is
closer to the normal content in mimic blood (1.5 g urea, 0.04 g
L.sup.-1 lysozyme, and 1 g L.sup.-1 BSA), the BSA solution having
the concentration of 4 g L.sup.-1 was selected for the subsequent
dialysis experiments.
[0079] Finally, the pre-binding solution of BSA (4 g L.sup.-1) and
50 ppm of PBUTs (e.g, PC or IS) were prepared, and then performed
around 900 CV cycles (between -3 and +3V, preferably between -0.8
and +0.8 V; sweep rate: 100 mV s.sup.-1) of ES to elucidate the BSA
retention (in the PBUT-side), the change in free-PBUTs (in the
PBUT-side), and the dialysis ratio (in the PBS-side) by using the
CNF1-based HD device (denoted "CNF1 device") over 4 h of dialysis
treatment, as compared with those measured using a PES membrane
device (denoted "PES device") and CNF1 with applied ES (denoted
"CNF1-R device"). As displayed in FIG. 13a, at each time point
(t=0, 1, 2, 3, and 4 h) the PBUT-BSA solution was collected from
the PBUT-side reservoirs during the 4 h of dialysis treatment; the
sample was filled into the centrifugal column device (with
30-kDa-cutoff filter) to obtain the free-PC (or free-IS) solution
from the collected PC-BSA solution (or IS-BSA solution), where the
free-PC (or free-IS) ratio was estimated from the solution of the
bottom column; the corresponding BSA retention was estimated by
recovering and collecting the target solution from the top of
column. In FIGS. 13b and 13c, the CNF1 device featured a relatively
higher amount of BSA adsorption than that of the PES device,
thereby resulting in relatively a lower BSA retention in the
PBUT-side (79.3% for PC-BSA solution; 88.4% for IS-BSA solution)
compared with that of the PES membrane (82.7% for PC-BSA solution;
91.0% for IS-BSA solution); nevertheless, no matter which PC-BSA or
IS-BSA pre-binding solution was used in this demonstration, the
CNF1-R device provided additional electrostatic repulsion or
created an external charge disturbance between BSA and the
nanofiber surface. Therefore, the degree of desorption of BSA would
increase upon increasing the ES treatment time, and then it would
be removed simultaneously by the axial flow streams on the
PBUT-side, thereby preserving the greater BSA retention in the
PBUT-side (97.6% for PC-BSA solution; 99.3% for IS-BSA
Solution
[0080] Notably, using the static CNF1 and CNF1-R device setups to
study the ES effect on percentage of protein binding of the PBUTs,
the present invention validated that the CNF1-R device had the
ability to decrease the protein binding ratio from 89.5% for CNF1
to 87.2% (FIG. 14). For the measurement of the free-PBUT ratio from
dynamic dialysis, if a rejection phenomenon occurred between
free-PC and the membrane surface during the ES operation, it would
result in a positive value of the changed free-PC ratio; in
contrast, a negative value of the changed free-PC ratio would mean
that some adsorption or dialysis phenomenon may have been playing a
dominant role to simultaneously decrease the freshly free-PBUTs in
this system. If the dissociated rate of PC-BSA binding was less
than the clearance rate of PC, the present invention would also
observe a decreasing trend in the negative value of the changed
free-PC ratio. For example, the CNF1-R device exhibited a greater
decreasing trend in the free-PC ratio (-9.1%) than did the CNF1 and
PES devices (-6.8 and -8.5%, respectively), due to greater
adsorption phenomena of free-PC on the MWCNT/PEDOT:PSS filter
surface or a higher dialysis ratio on the PBS-side (FIG. 13d). In
stark contrast, the CNF1-R device exhibited a smaller changed
free-IS ratio (-3.5%) than did the others (-4.2% for CNF1; -7.4%
for PES), due to greater electrostatic repulsive interactions
occurring on the filter surface during the ES operation (FIG. 13e).
These findings are consistent with the clearance rates and
physicochemical properties of the uremic toxins (FIGS. 10e-g and
FIG. 10b, respectively), suggesting that the CNF1 device could
provide a much higher clearance rate (42.4%) for PC than for IS
(3.4%), due to stronger .pi.-.pi. interactions and weaker
negative-negative electrostatic repulsive interactions between PC
and the surface. As displayed in FIGS. 13f and 13g, when analyzing
the dialysis ratios of the PBUTs through the various dialysis
devices, although the PES device exhibited higher dialysis ratios
(2.4% for PC; 3.7% for IS) than all the others, the results hint at
the possibility that the enhancement in the dialysis rate (from 0.6
to 0.9% for the PC dialysis ratio; from 1.2 to 1.8% for the IS
dialysis ratio) was due to the efficient increase in the free
fraction of PBUTs when using the CNF1-R device (having a small
effective area of merely 3.3 cm.sup.2) under ES operation. This
result was highly reproducible. Notably, an advantageous feature of
the CNF1-based HD device is that it can be connected in series (for
the PBUT-side) to the front of a conventional artificial kidney and
provide electrically triggered dissociation of protein binding to
PBUTs, thereby making up for the deficiency in performance in
between.
CONCLUSION
[0081] The present invention have developed electrically conductive
MWCNT/PEDOT:PSS nanofiber mats on PES dialysis membranes as
BEI-based HD devices for effective removal of PBUTs from dialysis
fluids through electrically triggered dissociation of protein--PBUT
binding. The MWCNT/PEDOT:PSS nanofiber mats, prepared from a series
of quaternary blend solutions having different component mixtures
(MWCNT, PEDOT:PSS, PEO, GOPS), were fabricated through needle-type
electrospinning and then investigated format the levels of both
material design and device engineering. These MWCNT/PEDOT:PSS
composite nanofibers possessed long-term water-resistance and high
adhesion strengths on the PES dialysis membrane, due to the GOPS
acting as a thermal crosslinker and adhesion promoter,
respectively. The addition of MWCNTs in the PEDOT:PSS nanofibers
led to MWCNT/PEDOT:PSS composite nanofibers that featured enhanced
electrical conductivity and electrochemical properties, thereby
promoting effective ES operation in BEI devices. The
MWCNT/PEDOT:PSS nanofiber mats displayed high blood compatibility,
as characterized by good anticoagulant ability, low platelet
adhesion/dendrite formation, and negligible hemolysis to RBCs. The
optimized CNF1 nanofiber mats functioned as novel single-membrane
HD devices for studies of the removal efficiencies of three kinds
of PBUTs (PC, IS, and HA) and one kind of non-PBUT (CRT), and also
allowed investigations of the effect of ES on their binding with
the protein BSA. Most importantly, these results confirmed that,
under ES operation, CNF1-R devices can not only provide a high
removal rate of PC with long-term stability but also exhibit high
BSA retention after 4 h of simulated dialysis; therefore, they have
potential for use in HD applications when developing
next-generation bioelectronic medicines. To obtain more powerful HD
treatment platforms for greater overall dialysis performance, in
future applications these CNF1-R devices can be designed for
concurrent setup connected in series with conventional artificial
kidney devices and, thereby, enhance the blood-regeneration
performance for the removal of most uremic. toxins. It should be
noted that the removal of PBUTs is merely an exemplary description
in the embodiment of the present invention, and all protein-bound
substances should be removed by the powerful HD treatment platforms
of the present invention.
[0082] It will be understood that the above description of
embodiments is given by way of example only and that various
modifications may be made by those with ordinary skill in the art.
The above specification, examples, and data provide a complete
description of the present invention and use of exemplary
embodiments of the invention. Although various embodiments of the
invention have been described above with a certain degree of
particularity, or with reference to one or more individual
embodiments, those with ordinary skill in the art could make
numerous alterations or modifications to the disclosed embodiments
without departing from the spirit or scope of this invention.
* * * * *