U.S. patent application number 16/618384 was filed with the patent office on 2021-01-28 for method for preparing ratiometric electrochemical aptasensor for vaniline based on nanocomposite modified electrode.
This patent application is currently assigned to Qingdao University. The applicant listed for this patent is QINGDAO UNIVERSITY. Invention is credited to Rijun GUI, Xiaowen JIANG, Hui JIN, Yujiao SUN.
Application Number | 20210025844 16/618384 |
Document ID | / |
Family ID | 1000005326337 |
Filed Date | 2021-01-28 |
United States Patent
Application |
20210025844 |
Kind Code |
A1 |
GUI; Rijun ; et al. |
January 28, 2021 |
METHOD FOR PREPARING RATIOMETRIC ELECTROCHEMICAL APTASENSOR FOR
VANILINE BASED ON NANOCOMPOSITE MODIFIED ELECTRODE
Abstract
A method for preparing a ratiometric electrochemical aptasensor
for vanillin based on an aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode includes, dripping ZIF-8 nanocomposite doped with
ferrocene and Ketjenblack on the surface of the bare glassy carbon
electrode, and immersing this modified electrode in the chloroauric
acid solution. The cyclic voltammetry is employed to scan and
electrodeposit gold nanoparticles to obtain the gold
nanoparticle-deposited ZIF-8 nanocomposite. The aptamer of vanillin
is attached to gold nanoparticles via Au--S bonds to construct an
aptamer-coupled nanocomposite sensing platform. Then, the
electrochemical curves in the presence of different vanillin
concentrations are measured, the linear relationship between the
ratios of the current peak intensities of ferrocene and vanillin
and the molar concentrations of vanillin is fitted, and the
ratiometric electrochemical aptasensor for vanillin is
constructed.
Inventors: |
GUI; Rijun; (Qingdao,
CN) ; SUN; Yujiao; (Qingdao, CN) ; JIN;
Hui; (Qingdao, CN) ; JIANG; Xiaowen; (Qingdao,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QINGDAO UNIVERSITY |
Qingdao, Shandong |
|
CN |
|
|
Assignee: |
Qingdao University
Qingdao, Shandong
CN
|
Family ID: |
1000005326337 |
Appl. No.: |
16/618384 |
Filed: |
March 14, 2019 |
PCT Filed: |
March 14, 2019 |
PCT NO: |
PCT/CN2019/078076 |
371 Date: |
May 14, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 27/3278
20130101 |
International
Class: |
G01N 27/327 20060101
G01N027/327 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 2018 |
CN |
201811307069.3 |
Claims
1. A method for preparing a ratiometric electrochemical aptasensor
for vanillin based on an aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode, comprising the following steps: (1) dissolving
2-methylimidazole (Hmim) in ethanol, adding ferrocene and
Ketjenblack, stirring to obtain a homogenous mixture, adding zinc
nitrate to the homogenous mixture; and stirring evenly to obtain a
first solution, and then transferring the first solution to a
high-pressure reactor; wherein a reaction in the first solution is
continuously carried out for a period of time at a set temperature
to obtain a product, and the product is centrifuged, washed with
ethanol, and dried in a vacuum to obtain a
ferrocene-Ketjenblack-ZIF-8 nanocomposite; (2) dripping a
cross-linking agent Nafion on a surface of a polished bare glassy
carbon electrode, and then dripping and coating the
ferrocene-Ketjenblack-ZIF-8 nanocomposite on a surface of the
cross-linking agent Nafion to form a ferrocene-Ketjenblack-ZIF-8
nanocomposite modified glassy carbon electrode; immersing the
ferrocene-Ketjenblack-ZIF-8 nanocomposite modified glassy carbon
electrode in a buffer electrolyte solution, adding chloroauric acid
to the buffer electrolyte solution to obtain a second solution; and
then in a set potential range, employing cyclic voltammetry to scan
the second solution and generate gold nanoparticles in situ by
one-step electrodeposition, thereby obtaining a gold
nanoparticle-deposited ZIF-8 nanocomposite; (3) adding aptamer DNA
of the vanillin with a sulfydryl terminal on a surface of the gold
nanoparticle-deposited ZIF-8 nanocomposite, and incubating for a
period of time at 4.degree. C. to obtain an aptamer modified gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode; (4) using the aptamer modified gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode obtained from the step (3) as a working electrode, and
measuring electrochemical square-wave voltammetry curves in the
presence of different vanillin concentrations; taking current peak
intensities of the ferrocene and the vanillin as a reference signal
and a response signal, respectively, fitting a linear relationship
between ratios I.sub.response signal/I.sub.reference signal of the
current peak intensities of the ferrocene and the vanillin and
molar concentrations of the vanillin, and constructing the
ratiometric electrochemical aptasensor for the vanillin.
2. The method for preparing the ratiometric electrochemical
aptasensor for the vanillin based on the aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode according to claim 1, wherein, in the step (1), a
reaction temperature is 50-150.degree. C., a reaction time is 3-12
h, and a mass concentration ratio of the Hmim, the ferrocene, the
Ketjenblack, to the zinc nitrate is
(100-200):(100-500):(1-10):(50-100).
3. The method for preparing the ratiometric electrochemical
aptasensor for the vanillin based on the aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode according to claim 1, wherein, in the step (2), a dosage
of the Nafion is 1-10 uL, a mass concentration of the ZIF-8
nanocomposite is 1-10 mg/mL, a molar concentration of the
chloroauric acid is 0.1-1 .mu.mol/L, a potential range where the
cyclic voltammetry is used to scan is -0.1-1.5 V, a scanning rate
of the cyclic voltammetry is 10-100 mVs.sup.-1, and a scanning
number of the cyclic voltammetry is 5-30 cycles.
4. The method for preparing the ratiometric electrochemical
aptasensor for vanillin based on the aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode according to claim 1, wherein, in the step (3), a molar
concentration of the aptamer of the vanillin is 1-10 .mu.mol/L, and
an incubation time is 12-48 h.
5. The method for preparing the ratiometric electrochemical
aptasensor for the vanillin based on the aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode according to claim 1, wherein, in the step (4), a linear
detection range of the different vanillin concentration is 0.01-500
.mu.mol/L, and a detection limit of the vanillin is 1-10 nmol/L.
Description
CROSS REFERENCE TO THE RELATED APPLICATIONS
[0001] This application is the national phase entry of
International Application No. PCT/CN2019/078076, filed on Mar. 14,
2019, which is based upon and claims priority to Chinese Patent
Application No. 201811307069.3, filed on Nov. 5, 2018, the entire
contents of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure belongs to the crossing technical
field of nanocomposite and electrochemical sensor. More
specifically, the present disclosure relates to a method for
preparing a ratiometric electrochemical aptasensor for vanillin
based on an aptamer-gold nanoparticle-ferrocene-Ketjenblack-ZIF-8
nanocomposite modified electrode, and the prepared sensor can be
used to detect vanillin efficiently.
BACKGROUND
[0003] Metal-Organic Frameworks (MOFs) have the advantages of large
specific surface area, high porosity, ordered crystal structure and
good mechanical stability. Due to the generally poor conductivity
of MOFs, the research and application of MOFs in electrochemical
sensing have rarely been reported. As a zeolite-like MOFs, ZIF-8
has excellent thermal stability and chemical stability. The
composite prepared by mixing ZIF-8 with electroactive materials can
significantly improve the conductivity and electrochemical sensing
performance of ZIF-8. Ketjenblack is a carbon black produced by a
special production process. Compared with ordinary conductive
carbon black, high conductivity can be achieved by adding an
extremely low amount of Ketjenblack. The composite prepared by
mixing Ketjenblack and ZIF-8 not only has a large specific surface
area and a high porosity, but also has good electrical
conductivity.
[0004] Vanillin, having a chemical formula of
C.sub.8H.sub.8O.sub.3, is a flavor component of vanilla beans, and
is widely found in beets, vanilla beans, benzoin gum, balsam of
Peru, tolu balsam and some other products. Vanillin is a white
needle-like crystal or light yellow crystal powder with a strong
aroma, which is a widely used edible spice. Vanillin is widely used
in food, condiments, cosmetics, pharmaceuticals and other fields,
while excessive intake of vanillin in human body can cause
headaches, nausea, vomiting, kidney damage and other problems.
Therefore, simple, rapid, highly sensitive and quantitative
detection of vanillin is important for monitoring human health.
Currently, methods for detecting vanillin mainly include high
performance liquid chromatography, capillary electrophoresis,
ultraviolet absorption spectroscopy, fluorescence spectroscopy,
surface plasmon resonance, colorimetry, chemiluminescence,
voltammetry and others methods. With the advantages of simple
operation, fast signal response, low sample consumption, low cost
and high sensitivity, electrochemical sensing analysis can be used
for the efficient detection of vanillin.
[0005] Electrochemical detection of vanillin has been reported in
the literature. Peihong Deng et al. designed an electrode modified
by graphene functionalized with ferroferric oxide nanoparticles for
electrochemical detection of vanillin (Electrochemical Behavior and
Determination of Vanillin on Electrode Modified by Graphene
Functionalized with Ferroferric Oxide Nanoparticles, Peihong Deng,
Xiaopeng Liu, Quanguo He, Junhua Li, Journal of Hengyang Normal
University, 2017, 3, 71-77). Lixin Chen et al. reported an ionic
liquid modified carbon paste electrode for the determination of
vanillin in foods (Determination of Vanillin in Foods by Ionic
Liquid Modified Carbon Paste Electrode, Lixin Chen, Xintian Li,
Hong Fang, Yuan Zhou, Modern Food Science and Technology, 2013, 3,
629-632). Peihong Deng et al. applied for an invention patent for
the detection of vanillin in foods based on a graphene-cuprous
oxide composite film modified acetylene black electrode by an
electrochemical method (Graphene-Cuprous Oxide Composite Film
Modified Acetylene Black Electrode and Method for Detecting
Vanillin in Foods, Peihong Deng, Quanguo He, Rongying Zeng, Jun
Zhang, Chinese Invention Patent. Publication No. CN105973956A).
[0006] Currently, in the electrochemical method for detecting
vanillin, the interaction between electroactive substances and
vanillin causes changes in electrical signal strength, thereby
detecting vanillin. This method relies on a single electrochemical
signal output. The single-signal detection method is susceptible to
the factors including the background, reagent, system and
environmental conditions, resulting in the fluctuation of the
measurement results. In contrast, employing the dual-signal ratio
processing to obtain the intensity ratio of the signals realizes a
self-calibration function, which effectively eliminates the
interference of the self-signal and the background signal and
improves the accuracy and reliability of the detection results. In
this regard, the present disclosure designs a ratiometric
electrochemical aptasensor for vanillin based on an aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode. This novel electrochemical sensor can be used to detect
vanillin efficiently. So far, detecting vanillin by using a
ratiometric electrochemical aptasensor or the ratiometric
electrochemical aptasensor based on the aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode has not yet been reported in domestic and foreign
literature and patents.
SUMMARY
[0007] The objective of the present disclosure is to overcome the
deficiencies of the prior art described above, and to provide a
method for preparing a ratiometric electrochemical aptasensor for
vanillin based on an aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode, where the method is simple, low-cost and has
high-sensitivity.
[0008] In order to achieve the aforementioned objective, according
to the present disclosure, a process of preparing the ratiometric
electrochemical aptasensor for vanillin based on the aptamer-gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode includes the following steps.
[0009] (1) Dissolving 2-methylimidazole (Hmim) in ethanol, adding
ferrocene and Ketjenblack, stirring well to form a homogenous
mixture, adding zinc nitrate, stirring evenly and then transferring
to a high-pressure reactor. The reaction is continuously carried
out for a period of time at a set temperature, and the product is
centrifuged, washed with ethanol and dried in a vacuum to obtain a
ferrocene-Ketjenblack-ZIF-8 nanocomposite.
[0010] (2) Dripping a cross-linking agent Nafion on a surface of a
polished bare glassy carbon electrode, and then dripping and
coating the ferrocene-Ketjenblack-ZIF-8 nanocomposite to form a
ferrocene-Ketjenblack-ZIF-8 nanocomposite modified glassy carbon
electrode; immersing the ferrocene-Ketjenblack-ZIF-8 nanocomposite
modified glassy carbon electrode in a buffer electrolyte solution
and adding chloroauric acid. In a set potential range, the cyclic
voltammetry is used to scan to generate gold nanoparticles in situ
by one-step electrodeposition, thereby obtaining a gold
nanoparticle-deposited ZIF-8 nanocomposite.
[0011] (3) Adding aptamer DNA of vanillin with a sulfydryl terminal
on the surface of the gold nanoparticle-deposited ZIF-8
nanocomposite and incubating for a period of time at 4.degree. C.
to obtain an aptamer modified gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode.
[0012] (4) Using the modified electrode obtained from step (3) as a
working electrode, and measuring the electrochemical square-wave
voltammetry curves in the presence of different vanillin
concentrations; taking current peak intensities of ferrocene and
vanillin as a reference signal and a response signal, respectively;
fitting a linear relationship between ratios (I.sub.response
signal/I.sub.reference signal) of the two current peak intensities
and molar concentrations of vanillin and constructing the
ratiometric electrochemical aptasensor for vanillin.
[0013] In step (1), the reaction temperature is 50-150.degree. C.,
the reaction time is 3-12 h, and the mass concentration ratio of
Hmim, ferrocene, Ketjenblack to zinc nitrate is
(100-200):(100-500):(1-10):(50-100).
[0014] In step (2), the dosage of the Nafion is 1-10 uL, the mass
concentration of the ZIF-8 nanocomposite is 1-10 mg/mL, the
concentration of the chloroauric acid is 0.1-1 .mu.mol/L, the
potential range where the cyclic voltammetry is used to scan is
-0.1-1.5 V, the scanning rate is 10-100 mVs.sup.-1, and the
scanning number is 5-30 cycles.
[0015] In step (3), the concentration of the aptamer of vanillin is
1-10 .mu.mol/L and the incubation time is 12-48 h.
[0016] In step (4), the linear detection range of vanillin
concentration is 0.01-500 .mu.mol/L and the detection limit is 1-10
nmol/L.
[0017] The effects of the present disclosure are as follows. The
ZIF-8 nanocomposite doped with ferrocene and Ketjenblack is dripped
and coated on the surface of the glassy carbon electrode and this
modified electrode is immersed in the chloroauric acid solution as
the working electrode. The cyclic voltammetry is used to scan and
electrodeposit gold nanoparticles to obtain the gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode. The aptamer of vanillin is attached to gold
nanoparticles via Au--S bonds to construct an aptamer-coupled ZIF-8
nanocomposite sensing platform. Then, the ratios of the current
peak intensities of vanillin to ferrocene in the presence of
different vanillin concentrations are measured, the linear
relationship between the different ratios and the corresponding
concentrations of vanillin is fitted, and the ratiometric
electrochemical aptasensor for vanillin is constructed. Compared
with the prior art, the method of the present disclosure has simple
operations and low cost, where raw materials are easy to obtain,
the product has high electrochemical activity, and the ratiometric
signal has a strong anti-interference ability. The method has high
sensitivity and good accuracy, which can be developed into a novel
ratiometric electrochemical aptasensor for the efficient detection
of vanillin.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic diagram showing the preparation for
the ratiometric electrochemical aptasensor for vanillin based on
aptamer-gold nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite
modified electrode and the detection for vanillin;
[0019] FIG. 2 is a diagram showing electrochemical square-wave
voltammetry curves in the presence of different vanillin
concentrations determined by using the ratiometric electrochemical
aptasensor of the present disclosure;
[0020] FIG. 3 shows the linear relationship fitted between the
ratios of oxidation current peak intensities of vanillin and
ferrocene and different vanillin concentrations.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0021] The present disclosure will be further described in detail
below in conjunction with the drawings and specific
embodiments.
Embodiment 1
[0022] This embodiment relates to the preparation for the
ratiometric electrochemical aptasensor for vanillin based on an
aptamer-gold nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite
modified electrode and the ratiometric electrochemical detection
for vanillin. The preparation process and the principle of the
ratiometric electrochemical aptasensor are shown in FIG. 1, and the
specific process steps are as follows.
[0023] 2-methylimidazole (Hmim) is dissolved in ethanol. Ferrocene
and Ketjenblack are added for stirring well to obtain the
homogenous mixture, and then zinc nitrate is added for stirring
evenly and then being transferred to a high-pressure reactor,
wherein the mass concentration ratio of Hmim, ferrocene,
Ketjenblack, to zinc nitrate is 130:200:1:60. The reaction is
continuously carried out at 90.degree. C. for 6 h, and the product
is centrifuged, washed with ethanol, and dried in a vacuum to
obtain a ferrocene-Ketjenblack-ZIF-8 nanocomposite.
[0024] 2 uL of cross-linking agent Nafion is dripped on a surface
of a polished bare glassy carbon electrode, and then the
ferrocene-Ketjenblack-ZIF-8 nanocomposite with a concentration of 2
mg/mL is dripped and coated to form a ferrocene-Ketjenblack-ZIF-8
nanocomposite modified glassy carbon electrode. The electrode is
immersed in a buffer electrolyte solution, and chloroauric acid is
added to adjust the concentration to 0.2 .mu.mol/L. In the
potential range of -0.1-0.7 V, the cyclic voltammetry is used to
scan for 10 cycles at a scanning rate of 20 mVs.sup.-1 to generate
gold nanoparticles in situ by one-step electrodeposition, thereby
obtaining a gold nanoparticle-deposited ZIF-8 nanocomposite.
[0025] Aptamer DNA of vanillin with a sulfydryl terminal whose
concentration is 2 .mu.mol/L is dripped on the surface of the gold
nanoparticle-deposited ZIF-8 nanocomposite, and then incubated for
12 h at 4.degree. C. to obtain an aptamer modified gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode. The modified electrode is used as the working electrode,
and the electrochemical square-wave voltammetry curves in the
presence of different vanillin concentrations are measured. Taking
the current peak intensities of ferrocene and vanillin as a
reference signal and a response signal, respectively, the linear
relationship between the ratios (I.sub.response
signal/I.sub.reference signal) of the two current peak intensities
and the molar concentrations of vanillin is fitted, and the
ratiometric electrochemical aptasensor for vanillin is constructed.
As shown in FIG. 2 and FIG. 3, the linear detection range of the
vanillin concentration is 0.01-200 .mu.mol/L and the detection
limit is 3 nmol/L.
Embodiment 2
[0026] This embodiment relates to the preparation for the
ratiometric electrochemical aptasensor for vanillin based on a
nanocomposite modified electrode and the ratiometric
electrochemical detection for vanillin. The schematic diagram of
the preparation process and the principle is the same as embodiment
1, and the specific process steps are as follows.
[0027] 2-methylimidazole (Hmim) is dissolved in ethanol. Ferrocene
and Ketjenblack are added for stirring well to obtain the
homogenous mixture, and then zinc nitrate is added for stirring
evenly and then being transferred to a high-pressure reactor,
wherein the mass concentration ratio of Hmim, ferrocene,
Ketjenblack, to zinc nitrate is 150:300:2:80. The reaction is
continuously carried out at 120.degree. C. for 12 h, and the
product is centrifuged, washed with ethanol, and dried in a vacuum
to obtain a ferrocene-Ketjenblack-ZIF-8 nanocomposite.
[0028] 5 uL of cross-linking agent Nafion is dripped on a surface
of a polished bare glassy carbon electrode, and then the
ferrocene-Ketjenblack-ZIF-8 nanocomposite with a concentration of 5
mg/mL is dripped and coated to form a ferrocene-Ketjenblack-ZIF-8
nanocomposite modified glassy carbon electrode. The
ferrocene-Ketjenblack-ZIF-8 nanocomposite modified glassy carbon
electrode is immersed in a buffer electrolyte solution, and
chloroauric acid is added to adjust the concentration to 0.5
.mu.mol/L. In the potential range of -0.2-1.0 V, the cyclic
voltammetry is used to scan for 20 cycles at a scanning rate of 40
mVs.sup.-1 to generate gold nanoparticles in situ by one-step
electrodeposition, thereby obtaining a gold nanoparticle-deposited
ZIF-8 nanocomposite.
[0029] Aptamer DNA of vanillin with a sulfydryl terminal whose
concentration is 4 .mu.mol/L on the surface of the gold
nanoparticle-deposited ZIF-8 nanocomposite, and then incubated for
24 h at 4.degree. C. to obtain an aptamer modified gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode. The modified electrode is used as the working electrode,
and the electrochemical square-wave voltammetry curves in the
presence of different vanillin concentrations are measured. Taking
the current peak intensities of ferrocene and vanillin as a
reference signal and a response signal, respectively, the linear
relationship between the ratios (I.sub.response
signal/I.sub.reference signal) of the two current peak intensities
and the molar concentrations of vanillin is fitted, and the
ratiometric electrochemical aptasensor for vanillin is constructed.
The linear detection range of the vanillin concentration is
0.05-300 .mu.mol/L and the detection limit is 5 nmol/L.
Embodiment 3
[0030] This embodiment relates to the preparation for the
ratiometric electrochemical aptasensor for vanillin based on a
nanocomposite modified electrode and the ratiometric
electrochemical detection for vanillin. The schematic diagram of
the preparation process and the principle is the same as embodiment
1, and the specific process steps are as follows.
[0031] 2-methylimidazole (Hmim) is dissolved in ethanol. Ferrocene
and Ketjenblack are added for stirring well to obtain the
homogenous mixture, and then zinc nitrate is added for stirring
evenly and then being transferred to a high-pressure reactor,
wherein the mass concentration ratio of Hmim, ferrocene,
Ketjenblack, to zinc nitrate is 200:400:3:100. The reaction is
continuously carried out at 150.degree. C. for 8 h, and the product
is centrifuged, washed with ethanol, and dried in a vacuum to
obtain a ferrocene-Ketjenblack-ZIF-8 nanocomposite.
[0032] 8 uL of cross-linking agent Nafion is dripped on a surface
of a polished bare glassy carbon electrode, and then the
ferrocene-Ketjenblack-ZIF-8 nanocomposite with a concentration of 6
mg/mL is dripped and coated to form a ferrocene-Ketjenblack-ZIF-8
nanocomposite modified glassy carbon electrode. The
ferrocene-Ketjenblack-ZIF-8 nanocomposite modified glassy carbon
electrode is immersed in a buffer electrolyte solution, and
chloroauric acid is added to adjust the concentration to 0.8
.mu.mol/L. In the potential range of -0.5-1.5 V, the cyclic
voltammetry is used to scan for 30 cycles at a scanning rate of 50
mVs.sup.-1 to generate gold nanoparticles in situ by one-step
electrodeposition, thereby obtaining a gold nanoparticle-deposited
ZIF-8 nanocomposite.
[0033] Aptamer DNA of vanillin with a sulfydryl terminal whose
concentration is 5 .mu.mol/L is dripped on the surface of the gold
nanoparticle-deposited ZIF-8 nanocomposite, and then incubated for
36 h at 4.degree. C. to obtain an aptamer modified gold
nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified
electrode. The modified electrode is used as the working electrode,
and the electrochemical square-wave voltammetry curves in the
presence of different vanillin concentrations are measured. Taking
the current peak intensities of ferrocene and vanillin as a
reference signal and a response signal, respectively, the linear
relationship between the ratios (I.sub.response
signal/I.sub.reference signal) of the two current peak intensities
and the molar concentrations of vanillin is fitted, and the
ratiometric electrochemical aptasensor for vanillin is constructed.
The linear detection range of the vanillin concentration is 0.1-500
.mu.mol/L and the detection limit is 10 nmol/L.
[0034] The above descriptions are only some preferred embodiments
of the present disclosure. It should be noted that those skilled in
the art can also make several improvements and modifications
without departing from the principles of the present disclosure,
and these improvements and modifications shall still fall within
the protective scope of the present disclosure.
* * * * *