INTRODUCTION:

The growth in the field of nanotechnology in the recent years is due to the fascinating and the unusual properties of nanoparticles. The characterization and the mass production of these particles has always been the root of growth of nanotechnology¹. Nanoparticles are the particles which have dimensions of the order of 100 nm or less. Different methods like physical, chemical and hybrid methods are used for the synthesis of nanoparticles.

Due to high toxicity of chemicals employed in these methods, they limit their biomedical applications. These methods also generate toxic wastes which are not only hazardous to environment but also harmful to humans. The environment friendly and greener approach known as the biogenic approach are now being replaced by the expensive, outdated and inefficient physical, chemical and the hybrid methods².

The particles generated by this process have higher catalytic reactivity, an improved contact between the enzyme and the metal salt, greater surface area to volume ratio. Currently, there is production of metallic nanoparticles by reducing certain metals like silver, gold, copper, zinc, and titanium, etc. Various kinds of the silver nanoparticles have been synthesised such as silver nanoparticles (AgNPs), silver chloride nanoparticles (AgCl NPs), or a combination of both. AgNPs have various applications in the field of gene and drug delivery, electronics, bio labelling, sensors, filters. They also serve as a factor of antimicrobial agents, anticancer agents².

Green or biogenic nanoparticles are synthesised, when microorganisms grab the target ions from their respective environment and turn the metal ions into element metal through the enzymes which are generated by cell activities³. Green synthesis of the silver nanoparticles serves as an alternative for the physical and the chemical synthesis of nanoparticles⁴. According to the location where these nanoparticles are being formed, these have been classified into extracellular and intracellular synthesis⁵.

The intracellular synthesis method consists of the transport of ions into the microbial cell so as to form nanoparticles in presence of the enzymes. The extracellular synthesis methods of these nanoparticles involve the trapping of the metal ions on surface of the cells and then reducing these ions in presence of enzymes⁶.

Over the last few decades various microorganisms such as bacteria (Bacillus cereus^7, Staphylococcus aureus¹, Morganella sp.¹⁸), algae (Spirulina platensis⁸, Sargassum muticum¹⁷) actinomycetes (Thermoactinomyces sp.⁹, Thermomonospora sp.¹⁸) and fungal species (P. brevicompactum¹⁰, Neurospora crassa¹, Phaenerochaete chrysosporium¹⁸) have been reported but comparative to these microorganisms reports are very less in case of yeast in the biosynthesis of silver nanoparticles. The present study deals with the isolation and screening of potential yeast strains for the biosynthesis of silver nanoparticles. Optimization of various parameters like carbon source, substrate concentration, temperature, pH and incubation period have been optimized to enhance the biosynthesis of AgNPs.

Further characterization of biosynthesized Ag NPs was done by FTIR, XRD and AFM analysis. Antioxidant and antibacterial activity of the biosynthesized silver nanoparticles have also been evaluated in this study.

MATERIALS AND METHOD:

Sample collection and isolation of yeast strains:

Samples were collected from contaminated fruit effluent, curd, plastic dumped soil, jam, agricultural soil, activated sludge and industrial soil from Vellore area, located at 12.920219°N and 79.133306°E in Tamil Nadu, India. Serial dilution and spread plating technique had been used for the isolation of yeast colonies. The samples were serially diluted and the dilutions of 10^-4and 10^-5were plated on YEPD agar media plate, incubated for 48hours at 30^˚C to isolate yeast colonies. Isolated yeast strains obtained were subcultured on YEPD agar plates and slants were made and preserved at 4^˚C¹.

Screening of yeast isolates for biosynthesis of Silver nanoparticles:

The primary screening of yeast isolates for the biosynthesis of Silver nanoparticles (Ag-NPs) was done, the yeast isolates were inoculated in minimal salt media (MSM) (K₂HPO₄-3g/L, Na₂HPO₄-6g/L, NH₄Cl-2g/L, NaCl-5g/L, MgSO4-1g/L, yeast extract-10g/L, peptone-20g/L), pH 6.5±0.2 and incubated for 48hours at 30^˚C under agitation (120 rpm). The following were the conditions for screening (1)Aqueous solution of AgNO₃was added to 5ml of the growth medium of each yeast isolate and incubated for 7 days at 30^˚C under agitation (120rpm) in dark condition. (2)The broth culture of each yeast isolates was centrifuged at 4000 rpm for 10 min and to 5ml of cell free supernatant, aqueous solution of AgNO₃ was added and mixture was agitated in dark conditions for 7days at 30^˚C. (3) MSM broth was maintained as control, without AgNO₃ as per the above conditions. Finally, visible colour change was observed in both the culture broth and cell free supernatant reaction mixtures.

The mixtures and the control were verified for the biosynthesis of Ag-NPs by UV-Vis spectrophotometric analysis through wavelength scan from 200-800nm. The isolates showing Ag-NPs peak between 200-500nm were selected as potential strains for purification of Ag-NPs¹.Purification of the synthesized Ag NPs was done by suspending the pellet into 1 % of sodium citrate solution.

Optimization of growth parameters:

Effect of carbon sources:

The effect of an optimal carbon source is an important parameter which affects the biosynthesis of nanoparticles. Potential yeast strains were inoculated (2% inoculum) in 100 ml erlenmeyer flasks containing 50 ml of minimal salt media (MSM) (K₂HPO₄-3g/L, Na₂HPO₄-6g/L, NH₄Cl-2g/L, NaCl-5g/L, MgSO4-1g/L, yeast extract-10g/L), peptone-20g/L) supplemented by different carbon sources (20g/L) such as sucrose, fructose, dextrose, lactose, maltose, cellulose and corn starch separately to optimize the carbon source for maximum synthesis of Ag-NPs. The substrate concentration, pH, temperature and incubation period of the MSM media was maintained at 1mM, 6, 30˚C and 48 h respectively, throughout the experiment. Aqueous solution of AgNO₃ (1 mM) along with supernatant of modified MSM broth was served as control. All the experiments were conducted by keeping the other parameters constant at one time. Determination of carbon source for optimal production of Ag-NPs was done by the process as stated above ¹.

Effects of substrate (AgNO₃) concentration:

The effect of optimal substrate concentration mostly influence the synthesis and size of the nanoparticles. The potential yeast strains were subjected to grow in modified MSM media (K₂HPO₄-3g/L, Na₂HPO₄-6g/L, NH₄Cl-2g/L, NaCl-5g/L, MgSO4-1 g/L, yeast extract-10 g/L, peptone-20 g/Land fructose-20 g/L) by inoculating 2% of inoculum and incubated at 30˚C for 48 h. Cell free supernatant was separated by centrifugation at 4000 rpm for 10 min. Aqueous solution of AgNO₃ of different concentration ranging from 1mM, 3mM and 5mM were prepared and added as substrate to the 48 h old cell free supernatant of each of the yeast strains separately. Aqueous solution of AgNO₃ with different concentration (1, 3 and 5 mM) along with supernatant of modified MSM broth was served as control for the respective isolates. All the other parameters were kept constant during the experiment. The visual color change was photographically recorded after 24 h, followed by UV-Vis spectrophotometric analysis through a wave length scan from 800-200 nm to determine maximum Ag-NP Synthesis⁴.

Effects of pH:

The effect of optimal pH was determined by inoculating the potential yeast strains in modified MSM broth and culture filtrate was separated after 48 h of incubation period. Aqueous solution of 1mM AgNO₃was added to 25 ml of cell free supernatant in each of the 100 ml Erlenmeyer flask containing pH of different range (pH 3,4,5,6,7,8 and 9). Aqueous solution of 1mM AgNO₃ with different pH range of MSM media without culture supernatant served as control. pH was set using diluted NaOH or HCl solution. All the other parameters were kept constant during the experiment. The Visible colour change was photographically recorded for 24h followed by UV-Vis spectrophotometric analysis through a wave length scan from 200-800nm to determine maximum Ag-NPs Synthesis⁴.

Effects of temperature:

The potential yeast strains were cultured in MSM broth for 48 h, the culture filtrate was separated and aqueous solution of 1mM AgNO₃ was added and incubated at different temperature ranges (5,25,30,37 and 45^˚C). Aqueous solution of AgNO₃with different temperature range of MSM media without culture supernatant served as control. All the other parameters were kept constant during the experiment. The color change was photographically recorded after 24 hours and subjected to UV-Vis spectrophotometric analysis through a wave length scan from 200-800 nm to determine Ag-NP Synthesis¹¹.

Effects of incubation period:

The potential yeast strains were cultured in MSM broth for 48h, the culture filtrate was separated by centrifugation and aqueous solution of 1mM AgNO₃ was added and incubated at 30˚C. Aqueous solution of AgNO₃with MSM media without culture supernatant served as control. All the other parameters were kept constant during the experiment The visual colour change was photographically recorded after 6,24,36 and 48 h followed by UV-Vis spectrophotometric analysis through a wave length scan from 200-800 nm to determine optimal Ag-NP Synthesis¹¹.

Characterization of the biosynthesized silver nanoparticles:

Fourier Transform Infrared (FTIR) analysis:

FTIR analysis of the dried and powdered samples containing Ag-NPs synthesized by the potential yeast strain 5,8 and 13 were measured on a PerkinElmer instrument for a range of 500-4000 cm^{-1 3}.

X-Ray diffraction (XRD) analysis:

The X-Ray diffraction analysis of the dried and powdered sample containing Ag-NPs synthesized by the potential yeast strains was obtained using X’pert Pro Panalytical which had the CuK_αradiation (λ=1.54 A ), with a voltage of 40KV and a current of 20mA⁴.

Atomic-force Microscopy (AFM) analysis:

The surface topography of the biosynthesized silver nanoparticles (AgNPs) by each of the potent strains were analysed using Atomic Force Microscopic analysis. The synthesized Ag-NPs were dissolved in 100µl Chloroform, smeared on a glass slide and air dried for 5 minutes, which was then subjected to AFM analysis.

Antioxidant Activity:

The antioxidant activity was estimated using the DPPH (2,2- Diphenyl-2-picrylhydrazyl hydrate) radical scavenging assay. The antioxidant activity was estimated by observing the utilisation of DPPH assay. A stock solution was prepared by dissolving DPPH (0.02 mM) in methanol. One millilitre of this stock solution was added to 2 ml of the cell free supernatant of the each of the potent yeast strains. The mixture was shaken vigorously and allowed to stand at room temperature for 30min and the absorbance was measured at 517nm by using a UV-visible Spectrophotometer. Antioxidant activity was estimated bycalculating the percentage (%) of inhibition by following formula ¹³:

Evaluation of Antibacterial Activity:

Preliminary test:

The antimicrobial activity of silver nanoparticles was estimated by using the well diffusion method. The bacterial cultures were swabbed on the nutrient agar plates and wells were made using borer. The different concentrations of AgNPs (100µg/ml and 200µg/ml) were added to two wells on the nutrient agar plate. A reaction mixture without silver nanoparticles was served as the negative control and antibiotic amoxycillin served as the positive control. These plates were incubated overnight at temperature of 37˚C. After an overnight incubation period, the antimicrobial activity was analysed by the measuring the zone of inhibition¹².

Minimum Inhibitory assay (MIC):

The antimicrobial activity of silver nanoparticles was estimated by using the Minimum inhibitory assay (MIC). The different concentrations of AgNPs (5µg/ml, 50µg/ml, 100µg/ml and 200µg/ml) were added to the nutrient broth and incubated for 24 h at 37˚C. Optical density was measured at 670 nm and the minimum inhibitory concentration was determined.

RESULTS AND DISCUSSION:

Isolation and enumeration yeast strains:

From the collected food and soil samples, thirteen yeast isolates were obtained from 10^-4and 10^-5dilution plates on spread plated YEPD agar plate represented in figure 1(a).The colony forming unit (CFU/ml) count of 10^-4and 10^-5 dilution plates for respective samples were enumerated as 232x10⁴ CFU/ml (agricultural soil) followed by 339x10⁴ CFU/ml (activated sludge), 351x10⁴ CFU/ml (industrial soil),42x10⁴CFU/ml (curd), 113x10⁴(buttermilk) and 41x10⁵CFU/ml (buttermilk). Isolated yeast strains were further sub-cultured on YEPD agar and its morphological characteristics were demonstrated in Table 1.Microscopic observations were performed through simple staining using crystal violet stain which revealed distinct morphologically characteristics of yeast strains, tabulated in Table 1 (figure 1).

Table 1: Colony characterisation of yeast isolates

Yeast Isolates	Sources	Pigmentation	Colony Morphology	Method of replication
Isolate 1	Agricultural soil	Creamy white	Irregular	Ovoid
Isolate 2	Activated sludge	White	Irregular	Ogival
Isolate 3	Industrial soil	Translucent white	Irregular	Ovoid
Isolate 4	Fruit Juice	White	Circular	Cylindroids
Isolate 5	Curd	White	Circular	Ogival
Isolate 6	Marine soil	White	Circular	Ogival
Isolate 7	Curd	White	Spokes	Cylindroids
Isolate 8	Buttermilk	White	Lacy	Ovoid
Isolate 9	Marine soil	Translucent white	Irregular	Ovoid
Isolate 10	Jam	White	Circular	Spherical
Isolate 11	Plastic dumped soil	White	Coralline	Ovoid
Isolate 12	Grape juice	White	Coralline	Cylindroids
Isolate 13	Buttermilk	Translucent white	Irregular	Apiculate

Screening of yeast isolates for biosynthesis of Silver nanoparticles:

Primary screening:

To screen the yeast strains capable for synthesising Ag NPs, thirteen yeast strains were isolated from different sources and grown in minimal salt medium (MSM) broth for 48 h. The 48 h old culture broth of each of the yeast strains were centrifuged and cell free supernatant was separated. Aqueous solution 1 mM silver nitrate (AgNO₃₎ was added to the cell free supernatant and incubated for 7 days. After 7 days of incubation period, colour change from pale to dark brown was observed only in Isolate 5, 8 and 13, however, there was no color change observed in the control, this indicated that synthesis of Ag NPs was happened only due to the reduction of AgNO₃by the reductase enzyme secreted by the respective yeast isolates not by the action of other media components present in the supernatant showed in figure 2 (a).

Secondary screening:

To confirm the presence of Ag-NPs, the secondary screening that is UV –Vis Spectrophotometric analysis was done which showed absorbance peak around 400-450 nm, shown in figure 2(b). The three yeast isolates 5, 8 and 13 had showed maximum absorbance at 420 nm, indicating the synthesis of Ag-NPs, thus Isolate 5, 8 and 13 were selected for further studies. The mechanism of biosynthesis of silver nanoparticles could be because of the(i) participation of ATP and/or NADPH dependent nitrate reductase system; (ii) attraction between positively charged Ag and negatively charged components on the cell surface¹⁰.

Optimization of growth parameters:

Effect of carbon source:

After studies the result showed that the both dextrose and fructose were utilized by the yeast strains for the production of silver nanoparticles but the immediate and better result was shown in fructose as a carbon substrate. Thereby all the further studies was conducted using fructose as the carbon source. The yeast isolates by utilizing fructose sugar produced certain extracellular metabolites which reduced the AgNO₃ to elemental Ag-NPs.

Effect of substrate (AgNO3) concentration:

The change in colour was observed which indicated the synthesis of silver nanoparticles. It was observed that the Ag nanoparticles formation increases with increase in substrate concentration, thus 5mM showed appreciable result and this was confirmed by UV-vis spectroscopy shown in figure 3(b), which also showed maximum absorbance in 5mM substrate concentration for isolates 5 and 13, whereas isolate 8 showed maximum absorbance at 3mM substrate concentration. Similar work had been reported by Rati Ranjan in 2011⁴.

Effect of pH:

It was observed that the absorption band of Ag nanoparticles is centred at 420 nm. pH 9.0 showed the maximum absorbance for Isolate 5 and 13 whereas, Isolate 8 showed the maximum absorbance at pH 8.0 shown in figure 3(c). The increase the pH of the cell free supernatant showed rapid Ag-NPs production because it is an efficient electron donor resulting in complete reduction of silver ions to nanoparticles, similar work had been reported by Saxena in 2016 ¹¹.

Table 2: Optimized growth parameters

Parameters	Isolate 5	Isolate 8	Isolate 13
Carbon source	Fructose	Fructose	Fructose
Substrate (AgNO₃)	5mM	3mM	5mM
pH	pH 9.0	pH 8.0	pH 9.0
temperature	45^oC	45^oC	45^oC
Incubation time	24 hours	24 hours	24 hours

Characterization of Ag nanoparticles:

FTIR analysis:

FTIR analysis of the dried samples of the biosynthesized AgNPs by Isolate 5, 8 and 13 showed the intense absorption bands around 3441-3197, 3444-3255 and 3441-3246 cm^-1 for the primary amine group and at 2944, 2922 and 2964 cm^-1 for secondary amine group respectively (Table 3). Other strong prominent peaks at wave numbers 1576, 1577 and 1539 cm^-1 represented the presence of C-C stretching groups of the biosynthesized AgNPs by isolate 5, 8 and 13 respectively. Intense absorption band at 1415 cm^-1 was observed only in case of AgNPs synthesized by Isolate 5 which is corresponding to the C-N vibrations, mostly present in protein molecules. Strong peaks at 1384 and 1276 cm^-1 were corresponding to the residual of nitrate and presence of amide III, observed in all the cases. Absorption bands at 1153 and 1076 cm^-1, were observed which were representing the C-O-C group of the AgNPs in each of the cases. Therefore, the presence of free amine groups increases the protein binding ability of the synthesised nanoparticles, thus increasing their stability Similar work has been reported by Gajbhiye in 2009 ³.

Figure 4: FTIR analysis of the biosynthesised silver nanoparticles by (a) Isolate 5, (b) Isolate 8 and (c) Isolate 13.

X- Ray diffraction:

The X-Ray diffraction graph patterns of the AgNPs synthesized by three isolates 5, 8 and 13 revealed the crystalline structure of the silver nanoparticles. The peaks at the 2 theta values of isolate 5 are; 27.29°, 31.76°, 45.91° 54.26°, 56.77°, 75.99° which are corresponding to (111),(200), (200), (311), (222) and (331) lattice of silver nanoparticles, represented in figure 5 (a).

Table 3: FTIR peaks indicating the functional groups present in the synthesized Ag-NPs.

FTIR spectra of AgNPs synthesized by:			Assigned functional groups
Isolate 5	Isolate 8	Isolate 13	Assigned functional groups
3441	3444	3441	Primary amine
3197	3255	3246	Primary amine
2966	2922	2964	Secondary amine
1579	1577	1579	Aromatic -C-C- skeletal vibration
1415	-	-	C-N stretching vibrations of aromatic amines
1384	1384	1384	Residual NO^3-
1276	1276	1276	Amide III
1153	1153	1153	-C-O-C-
1076	1076	1076	-C-O-C-

Peaks of silver nanoparticles synthesized by isolate 8 are 27.49°, 31.76°, 45.91°, 54.44°, 75.56° that are corresponding to (111), (200), (200), (311), and (331) revealed the presence of lattice of silver nanoparticles, represented in figure 5 (b). Similarly, Ag-NPs synthesized by isolate13 are 27.29°, 31.76°, 45.91°, 54.26° that corresponded to (111), (200), (200), (311) planes of the cubic crystalline phase of the metallic silver, represented in figure 5 (c). The values of the peaks at 2 theta correspond to the standard values of silver reported by Joint Committee on Powder Diffraction Standards File No. 040783. Thus the X-Ray Diffraction spectrum confirmed the presence of the silver nanoparticles. Similar trend was reported by Shaligramin 2009 ¹⁴.

Figure 5: The X-Ray diffraction graph patterns of the AgNPs synthesized by (a) Isolate 5 ;(b) Isolate 8 and (c) Isolate 13, revealed the crystalline structure of the silver nanoparticles in a, b and c respectively.

AFM analysis:

The silver nanoparticles synthesized by three isolates 5, 8, 13 were analysed using AFM. AFM images of the silver nanoparticles were showed in figure 6, which revealed the AgNPs films, deposited on the slides by spin coating. This was measured in the scanning proof microscope in the tapping mode under the ambient conditions.The atomic force microscopic images of the biosynthesized silver nanoparticles by isolates 5, 8, 13 represented in figure 6 (a), (b) and (c) respectively, revealed different surface topology of the AgNPs. Similar trends had been reported by Hemath Naveen in 2010 ¹⁹.

Figure 6: The atomic force microscopic images of the biosynthesized silver nanoparticles revealed distinct surface topology by (a) Isolate 5, (b) Isolate 8 and (c) Isolate 13 respectively.

Antioxidant activity of silver nanoparticles colloidal solution:

DPPH (2,2–Diphenyl-2-picyrlhydrazyl hydrate) radical scavenging assay was considered for the analysis of the antioxidant potential of silver nanoparticles synthesised from isolated yeast strains. Oxidation of molecules will produce unstable free radicals which damage the cells; an antioxidant prevents or stops such oxidation reactions and also forms stable free radicals. This will eliminate the oxidative stress produced by the free radicals. The results showed visible colour change of the assay mixture from dark purple to yellow after incubation shown in figure 7(a), the nanoparticles produced by cell free supernatant of isolate 5 showed a maximum of 83.05% DPPH scavenging effect and that of isolate 8 and 13 showed 41.24% and 20.90% respectively. Similar work has been reported by Nagaich et al in 2016 ¹³.

Antibacterial activity of biosynthesized silver nanoparticles:

The study of antimicrobial effectiveness was done for the synthesised Ag-NPs through a preliminary test which showed zone of inhibition against five bacterial cultures, at concentration of 100µg/ml and 200µg/ml of Ag-NPs synthesized by Isolate 5, 8 and 13 represented as A,B and C respectively and amoxycillin as positive control, represented in figure 7(b). This was further confirmed through Minimum Inhibitory Concentration assay against 24 h bacterial broth cultures as mentioned in Table 4. At concentration of 5µg/ml, 50µg/ml,100µg/ml and 200µg/ml of the synthesised AgNPs a significant decrease in the turbidity of the broth cultures was observed comparative to the control broth cultures. This indicated that at higher concentration of the Ag-NPs i.e. 200µg/ml there was appreciable bactericidal effect as graphically shown in the figure 7(c). Similar work has been reported by Maitiin 2014 ¹².

Table 4: Evaluation of zone of inhibition (in cm) against bacterial cultures by AgNPs synthesized using Isolate 5, 8 and 13.

Bacterial cultures	AgNPs using Isolate 5 (µg/ml)				AgNPs using Isolate 8 (µg/ml)				AgNPs using Isolate 13 (µg/ml)
Bacterial cultures	+ve C	-veC	100	200	+veC	-veC	100	200	+veC	-veC	100	200
B1	1.4	0	1.5	1.7	1.6	0	1.8	1.9	1.5	0	1.6	1.7
B2	1.5	0	1.7	1.9	1.7	0	1.9	2.1	1.0	0	2.0	2.1
B3	2.1	0	1.6	1.9	2.8	0	2.1	2.3	2.2	0	1.8	1.9
B4	1.7	0	1.9	2.0	1.5	0	1.3	1.7	1.9	0	1.6	1.9
B5	1.4	0	1.6	1.8	1.5	0	1.6	1.8	1.7	0	1.8	1.9

B1 (Staphylococcus aureus); B2 (Bacillus spp.), B3 (E.coli); B4 (Klebsiella); B5 (Pseudomonas spp.); +ve C (Positive control); –ve C(Negative control)

Figure 7: (a)Positive DPPH Scavenging activity shown in Ag-NPs synthesized by Isolate 5, 8 and 13; (b) Preliminary antibacterial test which showed zone of inhibition against five bacterial cultures (c) Graphical representation of effect of synthesized Ag-NPsby Isolate 5, 8 and 13 on growth of bacteria.

CONCLUSION:

From the current study, Isolate 5, Isolate 8, and Isolate 13 have been considered as potential yeast strains in the biosynthesis of silver nanoparticles. Different growth parameters have been optimised for the enhancement of biosynthesis of silver nanoparticles. Maximum biosynthesis of silver nanoparticles was observed with 3 and 5 mM AgNO₃ substrate concentration after 24 h of incubation period at 45°C grown in the media of pH 9.0 and 8 supplemented by fructose as a carbon source. The silver nanoparticles revealed a characteristic absorption peak at 420 nm through UV spectrophotometric analysis. The biosynthesised silver nanoparticles were characterised using FTIR, AFM and XRD, which confirmed their presence. FTIR analysis showed the possibility of protein being a stability material in the biosynthesised nanoparticles wherein, XRD analysis confirmed the crystalline structure of these nanoparticles. The AFM analysis revealed the distinct surface topology of the Ag-NPs synthesized by each of the isolates. Ag-NPs of Isolate 5 showed the maximum scavenging effect of DPPH, thus possessing the maximum antioxidant activity. The antibacterial activity tests concluded that the silver nanoparticles are found to be bacteriostatic at low concentration and bactericidal at high concentrations. Therefore these AgNPs can be serve as a preventive for the bacterial contamination. The synthesised silver nanoparticles can be used as potent antibacterial which is of interest in pharmaceutical field and also can be used as a potent antioxidant, as drugs and in dietary supplements.

ACKNOWLEDGEMENT:

The authors are grateful to the School of Advance Sciences, VIT University, Tamil Nadu, India for extending their support and providing laboratory facilities to complete this work.

CONFLICT OF INTERESTS:

There is no conflict of interests among the authors.

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Received on 06.06.2017 Modified on 07.07.2017

Research J. Pharm. and Tech 2018; 11(1): 83-92

DOI: 10.5958/0974-360X.2018.00016.1