U.S. patent application number 14/617537 was filed with the patent office on 2016-08-11 for method of producing biogenic silica nanoparticles.
The applicant listed for this patent is KING SAUD UNIVERSITY. Invention is credited to ALI ABDULLAH ALSHATWI, JEGAN ATHINARAYANAN, VAIYAPURI SUBBARAYAN PERIASAMY.
Application Number | 20160229699 14/617537 |
Document ID | / |
Family ID | 56507191 |
Filed Date | 2016-08-11 |
United States Patent
Application |
20160229699 |
Kind Code |
A1 |
ALSHATWI; ALI ABDULLAH ; et
al. |
August 11, 2016 |
METHOD OF PRODUCING BIOGENIC SILICA NANOPARTICLES
Abstract
A method of producing biogenic silica nanoparticles comprises
pretreating seed hulls of a biogenic source with an acid to form
acid-treated seed hulls; placing the acid-treated seed hulls in an
autoclave at a temperature greater than 100.degree. C. for about 2
hours under a fixed pressure; isolating the seed hulls; washing the
seed hulls with water; air drying the seed hulls; calcining the
seed hulls at a temperature range of 500.degree. C. to 700.degree.
C. for at least one hour in a furnace to produce biogenic silica
nanoparticles. The biogenic silica nano-particles are amorphous and
biocompatible possessing a particle sizes in the range of 25-75
nm.
Inventors: |
ALSHATWI; ALI ABDULLAH;
(RIYADH, SA) ; ATHINARAYANAN; JEGAN; (RIYADH,
SA) ; PERIASAMY; VAIYAPURI SUBBARAYAN; (RIYADH,
SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KING SAUD UNIVERSITY |
RIYADH |
|
SA |
|
|
Family ID: |
56507191 |
Appl. No.: |
14/617537 |
Filed: |
February 9, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01B 33/126 20130101;
C01B 33/18 20130101; C01P 2004/64 20130101; C01B 33/12
20130101 |
International
Class: |
C01B 33/18 20060101
C01B033/18 |
Claims
1. A method of producing biogenic silica nanoparticles comprising:
pretreating seed hulls of a plant with an acid to form acid-treated
seed hulls; heating the acid-treated seed hulls at a temperature
greater than 100.degree. C. for about 2 hours under pressurized
conditions; washing the acid-treated seed hulls with water to
remove the acid from the seed hulls; drying the seed hulls after
removing the acid; and calcining the dried seed hulls at a
temperature ranging from about 500.degree. C. to about 700.degree.
C. for at least one hour in a furnace to produce biogenic silica
nanoparticles, wherein the plant is selected from the group
consisting of Eleusine coracana, Sorghum bicolor and Pennisetum
glaucum, and the biogenic silica nanoparticles are between about 10
nm and about 100 nm in size.
2. The method of producing biogenic silica nanoparticles according
to claim 1, wherein the acid is 1 N hydrochloric acid.
3. The method of producing biogenic silica nanoparticles according
to claim 1, wherein the pressurized conditions include about 15 lbs
of pressure per square inch.
4. The method of producing biogenic silica nanoparticles from a
biogenic source according to claim 1, wherein the acid-treated seed
hulls are heated in an autoclave at a temperature of about
120.degree. C.
5. (canceled)
6. The method of producing biogenic silica nanoparticles according
to claim 1, wherein the biogenic silica nanoparticles are between
about 20 nm and 75 nm in size.
7. The method of producing biogenic silica nanoparticles according
to claim 1, wherein the silica nanoparticles are amorphous.
8. The method of producing biogenic silica nanoparticles according
to claim 1, wherein the silica nanoparticles are aggregated.
9. Biogenic silica nanoparticles produced by a method, the method
comprising: pretreating seed hulls of a plant with an acid to form
an acid-treated seed hulls; heating the acid-treated seed hulls at
a temperature greater than 100.degree. C. for about 2 hours under
pressurized conditions; washing the acid-treated seed hulls with
water to remove the acid from the seed hulls; drying the seed hulls
after removing the acid; and calcining the dried seed hulls at a
temperature range of 500.degree. C. to 700.degree. C. for at least
one hour in a furnace to produce biogenic silica nanoparticles,
wherein the plant is selected from the group consisting of Eleusine
coracana, Sorghum bicolor and Pennisetum glaucum, and the biogenic
silica nanoparticles are between about 10 nm and about 100 nm in
size.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to agri-nanotechnology, and
particularly to a method of preparing biogenic silica nanoparticles
from the seed hulls of various plants.
[0003] 2. Description of the Related Art
[0004] Nanomaterials, defined as particles with a size of less than
100 nm, have been useful in various industries, including,
electrical, textile, medicine, cosmetics, agriculture and food.
Nanomaterials have unique physiochemical properties. Silica is the
second most abundant element on earth. Silica nanoparticles
(SiO.sub.2-NPs) have been used in various applications including
catalysis, pigments, thin film substrates, thermal insulators,
pesticides, food additives, drug delivery, gene therapy, molecular
imaging and additives in plastics. Silica plays an important
physiological role in plants; as an alleviator of biotic and
abiotic stress. Silicon supplement diets have increased the bone
mineral density in women, increased type I collagen synthesis, and
induced osteoblast differentiation.
[0005] Biosilica is a selective inducer of osteoprotegerin
expression resulting in inactivation of osteoclast differentiation.
Silica inhibits the aluminum uptake in the gastrointestinal tract
due to the interaction between aluminum and silica.
[0006] Silica nanoparticles (SiO.sub.2-NPs) are used in numerous
applications and, as a consequence, large quantities are required.
Thus, there is a need to develop an easy and economical method to
produce SiO.sub.2-NPs.
[0007] A variety of methods have been used for preparing silica
nanoparticles namely, microwave hydrothermal process, flame
synthesis, sol-gel process, micro-emulsion method, and combustion
synthesis. In large scale production of silica, quartz sand is
treated with sodium carbonate at 1300.degree. C. This method is
hazardous to the environment because it emits a large quantity of
CO.sub.2 gas. Moreover, presently there is a major problem in
sustainability due to the generation of a large quantity of
agricultural waste. It has been estimated that 140 billion metric
tons of agricultural waste is generated every year worldwide due to
agricultural production and processing. However, huge quantity of
agricultural waste management is difficult and represents a major
challenge. The improper usage of agricultural wastes creates an
ecological contamination. Therefore, it would be desirable to
convert agricultural waste to valuable products in an efficient way
for industrial use.
[0008] Thus, a method of producing biogenic silica nanoparticles
from the bio-precursors of cultivated plants solving the
aforementioned problems is desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1A shows an X-ray Diffraction (XRD) pattern of biogenic
silica nanoparticles prepared from Elucine corcana using
calcination temperatures of 500.degree. C., 600.degree. C., and
700.degree. C.
[0010] FIG. 1B shows an X-ray Diffraction (XRD) pattern of biogenic
silica nanoparticles prepared from Sorghum bicolor using
calcination temperatures of 500.degree. C., 600.degree. C., and
700.degree. C.
[0011] FIG. 1C shows an X-ray Diffraction (XRD) pattern of biogenic
silica nanoparticles prepared from Pennisetum glaucum using
calcination temperatures of 500.degree. C., 600.degree. C., and
700.degree. C.
[0012] FIG. 2A shows the Transmission Electron Micrograph (TEM)
image of the biogenic silica nanoparticles prepared from Eleusine
coracana husk using a calcination temperature of 500.degree. C.
[0013] FIG. 2B shows the Transmission Electron Micrograph (TEM)
image of the biogenic silica nanoparticles prepared from Eleusine
coracana husk using a calcination temperature of 600.degree. C.
[0014] FIG. 2C shows the Transmission Electron Micrograph (TEM)
image of the biogenic silica nanoparticles prepared from Eleusine
coracana husk using a calcination temperature of 700.degree. C.
[0015] FIG. 3A shows the Transmission Electron Micrograph (TEM)
image of the biogenic silica nanoparticles prepared from Sorghum
bicolor husk using a calcination temperature of 500.degree. C.
[0016] FIG. 3B shows the Transmission Electron Micrograph (TEM)
image of the biogenic silica nanoparticles prepared from Sorghum
bicolor husk using a calcination temperature of 600.degree. C.
[0017] FIG. 3C shows the Transmission Electron Micrograph (TEM)
image of the biogenic silica nanoparticles prepared from Sorghum
bicolor husk using a calcination temperature of 700.degree. C.
[0018] FIG. 4A shows the Transmission Electron Micrograph (TEM)
image of the biogenic silica nanoparticles prepared from Pennisetum
glaucum husk using a calcination temperature of 500.degree. C.
[0019] FIG. 4B shows the Transmission Electron Micrograph (TEM)
image of the biogenic silica nanoparticles prepared from Pennisetum
glaucum husk using a calcination temperature of 600.degree. C.
[0020] FIG. 4C shows the Transmission Electron Micrograph (TEM)
image of the biogenic silica nanoparticles prepared from Pennisetum
glaucum husk using a calcination temperature of 700.degree. C.
[0021] FIG. 5A shows a graph of results of the cell viability assay
of human mesenchymal stem cells treated with biogenic silica
nanoparticles prepared using Eleusine coracana.
[0022] FIG. 5B shows a graph of results of the cell viability assay
of human mesenchymal stem cells treated with biogenic silica
nanoparticles prepared using Sorghum bicolor.
[0023] FIG. 5C shows a graph of results of the cell viability assay
of human mesenchymal stem cells treated with biogenic silica
nanoparticles prepared using Pennisetum glaucum.
[0024] FIG. 6 shows the nuclear morphology of human mesenchymal
stem cells treated with Eleusine coracana biogenic silica
nanoparticles prepared using a calcination temperature of
700.degree. C.
[0025] FIG. 7 shows the nuclear morphology of human mesenchymal
stem cells treated with Sorghum bicolor biogenic silica
nanoparticles prepared using a calcination temperature of
700.degree. C.
[0026] FIG. 8 shows the nuclear morphology of human mesenchymal
stem cells treated with Pennisetum glaucum biogenic silica
nanoparticles prepared using a calcination temperature of
700.degree. C.
[0027] Similar reference characters denote corresponding features
consistently throughout the attached drawings.
SUMMARY OF THE INVENTION
[0028] A method of producing biogenic silica nanoparticles includes
pretreating seed hulls of a plant with an acid to form acid-treated
seed hulls, placing the acid-treated seed hulls in an autoclave at
a temperature greater than 100.degree. C. for about 2 hours under
pressurized conditions, isolating the seed hulls, washing the seed
hulls with water, air drying the seed hulls, calcining the seed
hulls at a temperature range of about 500.degree. C. to about
700.degree. C. for at least one hour in a furnace to produce
biogenic silica nanoparticles. The plant can be millet (Eleusine
coracana), sorghum (Sorghum bicolor), and pearl millet (Pennisetum
glaucum). The biogenic silica nanoparticles are amorphous and
biocompatible. The biogenic silica nanoparticles range from about
20 nm to about 75 nm in size.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] A method of producing biogenic silica nanoparticles includes
pretreating seed hulls of a plant with an acid to form a mixture,
placing the mixture in an autoclave at a temperature greater than
100.degree. C. for about 2 hours under pressurized conditions,
isolating the seed hulls, washing the seed hulls with water; air
drying said seed hulls, calcining the seed hulls at a temperature
range of about 500.degree. C. to about 700.degree. C. for at least
one hour in a furnace to obtain biogenic silica nanoparticles. The
plant can be millet (Eleusine coracana), sorghum (Sorghum bicolor),
and pearl millet (Pennisetum glaucum). The biogenic silica
nanoparticles are amorphous and biocompatible. The biogenic silica
nanoparticles range from about 20 nm to about 75 nm in size.
[0030] Millet, (Eleusine coracana), sorghum (Sorghum bicolor), and
pearl millet (Pennisetum glaucum) are important traditional crops
in Saudi Arabia and elsewhere. The seed hulls of these plants
contain approximately 5-15% of silica, 80-85% of organic materials
and traceable quantity of metal ions. The hulls are the natural
shells or sheaths that form the outer covering of the grains, which
are the seeds. They are removed during the refining process and
remain as low value by-product and agricultural waste.
[0031] The hulls of the plant seeds can be ground and sieved. Then,
as mentioned above, the hulls can be treated with an acid to form
an acid-treated mixture. The acid can be, for example, 1 N
hydrochloric acid. The acid-treated mixture can be heated at a
temperature greater than 100.degree. C. For example, the
acid-treated mixture can be transferred to an autoclave and
maintained at 120.degree. C. for about 2 hours under pressurized
conditions, e.g. 15 lbs.
[0032] The elemental profile results of the biogenic silica
nanoparticles produced in accordance with the present method
indicated a purity of 99.53%. The biogenic silica nanoparticles
produced according to the present method are amorphous and range in
size from about 25 nm to about 75 nm. The biogenic silica
nanoparticles produced according to the present method are
non-toxic and bio compatible with human mesenchymal stem cells
(hMSc). The present method for providing biogenic silica
nanoparticles is simple, cost-effective, and well-suited for large
scale production. Accordingly, the biogenic silica nanoparticles
produced according to the present methods can be useful in
nutraceutical and dietary supplements, bone tissue engineering,
anti-caking agents, excipients associated with the food industry,
catalysts, water treatment and in other biomedical applications.
The selected plant seed hulls or bio-precursors described herein
can be used for synthesis of various materials including silica
nano-composites and zeolites. The following examples will further
illustrate the invention but are not to be construed as limiting
its scope.
EXAMPLE1
Materials and Methods
[0033] The seed hulls of Eleusine coracana, Sorghum bicolor, and
Pennisetum glaucum were collected from a post-harvesting mill, in
Karur, Tamil Nadu (India). The collected materials were ground and
sieved using 18 mesh size for further studies. Total silica content
of plant's seed hulls was quantified adopting AOAC procedures.
EXAMPLE 2
Cell Culture
[0034] Human mesenchymal stem cells (hMSc) were obtained from
Thermo Scientific Hyclone (USA). The cells were cultured in DMEM
medium supplemented with 10% bovine serum, 100 .mu.g/mL of
penicillin and 100 .mu.g/mL of streptomycin in 96-well culture
plates at 37.degree. C. in a humidified atmosphere containing 5%
CO.sub.2. All experiments were performed with cells from 15
passages or less.
EXAMPLE 3
Preparation of Biogenic Silica Nanoparticle from Plant
Materials
[0035] Approximately 100 grams of the selected seed hulls were
mixed with 500 ml of 1 N HC1 in separate conical flasks. These
mixtures were transferred to an autoclave and maintained at
120.degree. C. for 2 hours under pressurized (15 lb) conditions.
The acid-pretreated plant's seed hulls was isolated and washed with
Milli-Q water to remove the hydrochloric acid. Residue from the
acid-pretreated seed hulls were dried and subsequently calcinated
at temperatures of 500.degree. C., 600.degree. C., and 700.degree.
C. for 1 hour using a muffle furnace.
EXAMPLE 4
Characterization of the Biogenic Silica Nanoparticles
[0036] The crystalline nature of the obtained biogenic silica
nanoparticles were investigated using powder XRD (JEOL model). The
prepared biogenic silica powders were dispersed in pure ethanol and
ultrasonicated before transmission electron micrograph (TEM)
characterization. The morphologies and sizes of the samples were
examined using a JEOL transmission electron microscope (TEM) at an
accelerating voltage of 200 kV. Biogenic silica samples derived at
700.degree. C. were used for analysis of biological properties.
[0037] FIG. 1A shows the XRD pattern of the biogenic silica
nanoparticles derived from Eleusine coracana plant seed hulls.
Broad XRD peaks can be seen in FIG. 1A, with a 2.theta. value
between 15-35.degree. , which indicates that the formed silica
nanoparticles are amorphous. FIGS. 1B and 1C show the XRD pattern
of biogenic silica nanoparticles derived from Sorghum bicolor and
Pennisetum glaucum, respectively. The results show broad XRD peaks
corresponding to amorphous silica nanoparticles. The broadness of
the XRD peaks confirms that the prepared biogenic silica is
nanoscale in size.
[0038] The size and morphology of the prepared biogenic silica
nanoparticles were analyzed using transmission electron microscope
(TEM). FIGS. 2A-2C show the TEM images of the biogenic silica
nanoparticles derived from Eleusine coracana using calcination
temperatures of 500.degree. C. (FIG. 2A), 600.degree. C. (FIG. 2B),
and 700.degree. C. (FIG. 2C). The biogenic silica nanoparticles are
spherical and about 25-75 nm in size, but the particles are
aggregated. FIGS. 3A-3C show the TEM images of the prepared
biogenic silica nanoparticles from Sorghum bicolor using
calcination temperatures of 500.degree. C. (FIG. 3A), 600.degree.
C. (FIG. 3B), and 700.degree. C. (FIG. 3C). The indicate silica
nanoparticles are 20-60 nm in size and aggregated. It was
discovered that when the calcination temperature increased, the
particle size also increased. This result suggests that calcination
temperature plays a vital role in biogenic silica nanoparticles
formation. FIGS. 4A-4C show the TEM images of the Pennisetum
glaucum biogenic silica using calcination temperatures of
500.degree. C. (FIG. 4A), 600.degree. C. (FIG. 4B), and 700.degree.
C. (FIG. 4C). The TEM images confirmed that the prepared particles
were about 40-60 nm, and spherical in shape. However, the particle
size and shape varied based on their bio-precursor and calcination
temperatures. The purity of the prepared biogenic silica was
analyzed using ICP-OES. The results suggested that prepared samples
are highly pure (Table 1).
TABLE-US-00001 TABLE 1 Biogenic Silica Nanoparticles prepared from
seed hulls of various plant materials. Silica in seed Calcination
Biogenic silica Plants hulls (%) temperature nanoparticles (%)
Eleusine coracana 6.8 500.degree. C. 99.123 600.degree. C. 99.28
700.degree. C. 99.54 Sorghum bicolor 7.8 500.degree. C. 98.933
600.degree. C. 98.97 700.degree. C. 99.32 Pennisetum 6.1
500.degree. C. 99.53 glaucum 600.degree. C. 99.58 700.degree. C.
99.64
EXAMPLE 5
Cell Viability Assay
[0039] The biocompatibility of the prepared biogenic silica
nanoparticles were assessed by an MTT assay. The hMSc were seeded
at a density of 1.times.10.sup.4 cells per well in 200 .mu.L of
fresh culture medium and incubated overnight at 37 .degree. C. and
5% CO.sub.2. After overnight growth, the cells were treated with
different concentrations (25-400 ng/mL) of well characterized
biogenic silica nanoparticles for 24 and 48 h. After incubation, 20
.mu.L of MTT solution [5 mg/mL in phosphate-buffered saline (PBS)]
was added to each well. The plates were wrapped with aluminum foil
and incubated for 4 h at 37.degree. C. The plates were centrifuged,
and the purple formazan product was dissolved by the addition of
100 .mu.L of DMSO to each well. The absorbance was monitored at 570
nm (measurement) and 630 nm (reference) using a 96-well plate
reader (Bio-Rad, CA, USA). Data were collected for tetraplicates of
each biogenic silica nanoparticles concentration, and these data
were used to calculate the mean. The percent inhibition was
calculated from these data by the following formula:
Cell viability = Mean OD of untreated cells ( control ) - Mean OD
of treated cells .times. 100 Mean OD of untreated cells ( control )
##EQU00001##
[0040] FIGS. 5A-5C shows results of the cell viability assay of
human mesenchymal stem cells (hMSC) treated with biogenic silica
nanoparticles prepared using (a) Eleusine coracana (FIG. 5A), (b)
Sorghum bicolor (FIG. 5B), and (c) Pennisetum glaucum (FIG. 5C).
The hMSC were exposed to various concentrations (25, 50, 100, 200
and 400 .mu.g/mL) of biogenic silica nanoparticles derived from
various plant seed hulls for 24 hours. Ultimately, there was no
difference between the control and the low concentration group,
whereas slight changes were observed at the high concentration.
Because the cell viability was greater than 95% at the high
concentrations, the results indicate that prepared biogenic silica
nanoparticles exhibited biocompatibility with hMSCs.
EXAMPLE 6
Cellular Morphology Analysis
[0041] The nuclear and cytoplasmic morphology of the hMSc cells
were analyzed after treatment with biogenic silica nanoparticles
for 24 and 48 hours. Control cells were grown in the same manner in
the absence of biogenic silica nanoparticles. The cells were
trypsinized and fixed with methanol. The cell nuclei were then
stained by treatment with 1 mg/mL propidium iodide (Sigma) at
37.degree. C. for 15 min in the dark. The stained cells were
examined under an inverted fluorescence microscope (Carl Zeiss,
Jena, Germany). The results are presented as a series of
triplicates.
[0042] FIGS. 6, 7 and 8 show the nuclear morphology of human
mesenchymal stem cells (hMSC) treated with biogenic silica
nanoparticles derived at 700.degree. C. from seed hulls of Eleusine
coracana (FIG. 6), Sorghum bicolor (FIG. 7) and Pennisetum glaucum
(FIG. 8) respectively. The images revealed the presence of healthy,
round nuclei cells, without any significant changes in cell
morphology upon treatment of the hMSCs with the biogenic silica
nanoparticles, where Dose-1=50 .mu.g/mL and Dose-2=200 .mu.g/mL for
24 and 48 hours. The observations confirmed that the biogenic
silica nanoparticles are non-toxic and biocompatible with
hMSCs.
[0043] It is to be understood that the present invention is not
limited to the embodiments described above, but encompasses any and
all embodiments within the scope of the following claims.
* * * * *