Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 130 (2014) 13–18

Contents lists available at ScienceDirect

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa

Antimicrobial and antioxidant activities of Mimusops elengi seed extract mediated isotropic silver nanoparticles Hoskote Anand Kiran Kumar a, Badal Kumar Mandal a,⇑, Kesarla Mohan Kumar a, Sireesh babu Maddinedi a, Tammina Sai Kumar a, Pavithra Madhiyazhagan b, Asit Ranjan Ghosh b a b

Trace Elements Speciation Research Laboratory, Environmental and Analytical Chemistry Division, School of Advanced Sciences, VIT University, Vellore 632014, India Medical Biotechnology Division, School of Bio Sciences and Technology, VIT University, Vellore 632014, India

h i g h l i g h t s

g r a p h i c a l a b s t r a c t

 Biogenic synthesis of isotropic silver

nanoparticles using Mimusops elengi extract.  Identified secondary metabolites present in plant extract ceases agglomeration.  Synthesized Ag NPs show good antimicrobial and antioxidant activity.

a r t i c l e

i n f o

Article history: Received 1 November 2013 Received in revised form 4 March 2014 Accepted 9 March 2014 Available online 5 April 2014 Keywords: Mimusops elengi Isotropic Polyphenols Antioxidant Secondary metabolites

a b s t r a c t The present study reports the use of Mimusops elengi (M. elengi) fruit extract for the synthesis of silver nanoparticles (Ag NPs). The synthesized Ag NPs was initially noticed through visual color change from yellow to reddish brown and further confirmed by surface plasmonic resonance (SPR) band at 429 nm using UV–Visible spectroscopy. Morphology and size of Ag NPs was determined by Transmission Electron Microscopy (TEM) analysis. X-ray Diffraction (XRD) study revealed crystalline nature of Ag NPs. The prolonged stability of Ag NPs was due to capping of oxidized polyphenols which was established by Fourier Transform Infrared Spectroscopy (FTIR) study. The polyphenols present in M. elengi fruit extract was analyzed by High Pressure Liquid Chromatography (HPLC) and the results revealed the presence of ascorbic acid, gallic acid, pyrogallol and resorcinol. In order to study the role of these polyphenols in reducing Ag+ ions to Ag NPs, analyses of extracts before reduction and after reduction were carried out. In addition, the synthesized Ag NPs were tested for antibacterial and antioxidant activities against Staphylococcus aureus (S. Aureus) and Escherichia coli (E. coli). Ag NPs showed good antimicrobial activity against both gram positive (S. aureus) and gram negative (E. coli) bacteria. It also showed good antioxidant activity as compared to ascorbic acid as standard antioxidant. Ó 2014 Elsevier B.V. All rights reserved.

Introduction Nanoparticles (NPs) play a key role in bridging the advancements in interdisciplinary concepts. Nanomaterials synthesis and its applications is a promising area in the field of nanotechnology due its versatile scopes in semiconductors, photovoltaic devices, ⇑ Corresponding author. Fax: +91 4162243092. E-mail addresses: [email protected], [email protected] (B.K. Mandal). http://dx.doi.org/10.1016/j.saa.2014.03.024 1386-1425/Ó 2014 Elsevier B.V. All rights reserved.

coatings, biosensors and drug delivery. Noble metal NPs have gained a lot of attention due to their improved physicochemical properties [1]. Ag NPs are extensively used in various applications such as bio-labeling, sensors [2], electrodes [3] and integrated circuits [4]. In addition, Ag NPs are well-known for their antifungal and antimicrobial activity [1], hence they have been used in various industries, military, medicine, cosmetics and animal husbandry [5]. Many chemical and physical methods are available in synthesizing Ag NPs which includes chemical reduction, laser

14

H.A. Kiran Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 130 (2014) 13–18

ablation, thermal decomposition, microwave and sonoelectrochemical reduction [6–9], etc. Among them chemical reduction uses toxic chemicals during synthesis and also generates by-products which contaminates NPs [10], whereas other methods are very expensive and time overriding. Since Ag NPs are broadly used in human contacting applications [11], it is necessary to move towards non-toxic and cheap greener protocols. To fulfill the need of toxic contaminants free NPs majority researchers have opted green synthesis routes using enzymes, bacteria, fungi, yeast and plants extracts [12–14]. Among these biological methods plant mediated synthesis is mostly employed because of its simplicity, which avoids the lengthy procedure of maintaining cultures and monitoring reactions. Although many reports are available on the synthesis of Ag NPs using plant extracts [5], this subject is bringing lots of interest among the researchers in exploring the size, shape and property oriented applications. Mimusops elengi (M. elengi) is a medicinal plant belonging to family Sapotaceae which is rich in polyphenols and tannins [15]. Various parts of the plants have been used as traditional medicine for treating snake bite, chronic dysentery and bleeding of gums [16]. M. elengi has been evaluated for its antiulcer, anthelmintic, antihypertensive, antibacterial and antihyperlipidemic activities [17]. The present study describes synthesis of Ag NPs using M. elengi fruit pericarp extracts at room temperature, characterization and its applications in antimicrobial and antioxidant activities.

diffraction analysis and other studies. The scanning range was done in the region of 2h from 10° to 90° with a scanning rate of 4°/min and with a step size of 0.02° using Bruker D8 Advance diffractometer with Cu Ka radiation (k = 1.54 Å). Before analysis the instrument was calibrated using lanthanum hexaboride (LaB6). Fourier Transformed Infrared Spectroscopy (FTIR) study Purified Ag NPs were pulverized and analyzed using FT-IR spectroscopy. For FTIR analysis, Ag NPs were mixed with KBr and pelletized and the spectra was recorded using JASCO FT-IR 4100 instrument in the diffuse transmittance mode at a resolution of 4 cm 1. For comparison, Terminalia chebula fruit powder was pelletized and used as control. High Performance Liquid Chromatography (HPLC) study To know the possible water soluble phyto-constituents present in plant extracts HPLC analysis was done using Perkin Elmer 200 Series HPLC equipped with UV–Visible detector (192–700 nm) and a 200 Series pump. The sample was eluted using a mobile phase containing 0.1 M KCl and 32% acetonitrile (pH was adjusted to 3.0 with dil. HCl) using Brownlee Analytical C-18 (150  4.6 mm 5 lm 110 Å) column packed with silica particles. The detection was carried out using the UV–Visible detector at 260 nm with a flow rate of 1 mL min 1. The obtained peaks were compared and matched with external standards.

Experimental

Antibacterial activity

Preparation of M. elengi fruit extract

The synthesized Ag NPs were tested for antibacterial activity using Agar well diffusion method against Gram-positive bacteria Escherichia coli (strain ATCC 25922) and gram negative bacteria Staphylococcus aureus (strain ATCC 25923). Muller Hinton Broth (MHB) containing 1% Agar was used to prepare medium for easy diffusion of NPs. Bacterial lawn was prepared on sterile Muller Hinton Agar plates by using sterile cotton swabs, approximately 8 mm wells were made on the nutrient medium using gel puncture. Different concentrations of Ag NPs (10–50 lL) were placed in the specified wells and the plates were incubated at 37° overnight. The activity of Ag NPs against both the bacterial cultures was determined using standard minimum inhibitory concentration (MIC) by measuring the zone of inhibition (ZOI).

1.0 g of finely dried and grounded powder of M. elengi fruit (pericarp) was taken in a beaker containing 100 mL of deionised water and heated for 1 h at 90 °C in a temperature controlled water bath, then filtered through cellulose nitrate membrane filter paper (0.22 lm) and stored in refrigerator until use. Freshly prepared extracts was used throughout the work. Synthesis of Ag NPs 10 mL of freshly prepared M. elengi extract was added with 2 mL of 0.01 M AgNO3 and mixed scrupulously. Formation of Ag NPs was noticed by visual color change from colorless to reddish brown and kinetics of reduction was monitored spectrophotometrically. Characterization of Ag NPs Ultraviolet–Visible spectroscopy (UV–Visible) study Initial characterization of as-synthesized Ag NPs was done by UV–Visible spectroscopy after 5 folds dilution of the colloidal solution with deionized water and kmax was determined by recording spectra between 300 nm and 800 nm using Jasco V-670 UV–Visible double beam spectrophotometer. The obtained data was plotted using Origin 6.1 (1990–1998 InstallShield Software Corporation, USA).

Antioxidant activity Synthesized Ag NPs was checked for antioxidant activity by DPPH (1,1-diphenyl-2-picryl-hydrazil) method. The activity was measured by the following method wherein 3 mL of each different concentration of Ag NPs (20–100 lg/mL) was added to 1 mL methanolic solution of DPPH (20 ppm). Similar experiment was carried out simultaneously with ascorbic acid as standard antioxidant. The blank was also prepared by adding 1 mL DPPH to 3 mL of methanol. The tubes were kept in dark for 30 min; then absorbance was measured at 517 nm using UV–Visible spectrophotometer. Result and discussion

Transmission Electron Microscopy (TEM) study In order to determine the morphology of biosynthesized Ag NPs, 100 lL of the colloidal solution was diluted to 1 mL with deionized water, sonicated using ultrasonic bath and a drop of it was placed on Cu grid and dried in vacuum. Then NPs were visualized using JEOL JEM 2100 HR-TEM at an acceleration voltage of 200 kV. X-ray Diffraction (XRD) study After reduction Ag NPs were collected by centrifugation of reaction mixture at 10,000 rpm, purified, dried and subjected to X-ray

The addition of M. elengi extract to AgNO3 solution resulted visual color change from colorless to reddish brown within 5 min because of surface plasmon resonance (SPR) excitation due to the collective oscillation of free conduction electrons induced by an interacting electromagnetic field which is absent in bulk material [18] indicating the reduction of Ag+ to Ag0. Formation of Ag NPs was further confirmed by UV–Visible spectra by recording the absorption spectrum of the colloidal solution (Fig. 1A) with a characteristic SPR band at 429 nm with increasing time. The intensity

H.A. Kiran Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 130 (2014) 13–18

15

Fig. 1. UV–Visible spectra of the synthesized Ag NPs at different time intervals (A), stability studies of synthesized Ag NPs with time (B).

of the band increased due to the formation of more NPs and after 30 min there was no significant increase in band intensity which signifies that reaction was completed within 30 min. The absorption band in UV–Visible spectra is sensitive to the size and shape of the particles [19]. The single narrow band at 429 nm represents the formation of smaller Ag NPs [20]. It was also observed that synthesized Ag NPs were stable for more than 5 months which was confirmed by recording spectra in regular time intervals (Fig. 1B). Shape and morphology of the synthesized Ag NPs were determined by TEM analysis. The TEM images at different magnifications are shown in Fig. 2. The particles were almost spherical in nature with an average size of 23.5 nm (i.e. size of the synthesized nanoparticles were in the range of 12.8–30.48 nm). Fig. 2C shows the biomolecular capping on the surface of Ag NPs, which is responsible for enhanced stability of Ag NPs. Crystalline nature of

the nanoparticles was further confirmed by the SAED patterns with bright circular spots (Fig. 2D). Crystal behavior of the purified solid Ag NPs was determined using Powder XRD. Fig. 3 shows the XRD pattern of Ag NPs prepared using M. elengi extracts. A number of strong diffraction peaks are seen at 2h values of 38.25°, 44.30°, 64.39°, 77.35° and 81.37° which correspond to the (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) interplanar reflections of face centred cubic crystal structure respectively [21]. The lattice constants were in conformity with the database of Joint Committee on Powder Diffraction Standards (JCPDS. No. 01-087-0597), whereas broadening in the diffraction peaks indicates that small crystallite size is obtained [22]. The average particle size has been estimated by using Debye–Scherer formula [D = kk/bcos (h)] where D is the average crystal size, k is the Scherer coefficient (0.891), k is the X-ray wave length

Fig. 2. TEM images of Ag NPs at different magnifications of 100 nm, histogram (inset) showing particle size (A), 20 nm (B), biomolecular capping on to surface (C), and SEAD pattern (D).

16

H.A. Kiran Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 130 (2014) 13–18

Fig. 3. X-ray diffraction pattern of synthesized Ag NPs.

(k = 1.5406 Å), h is Bragg’s angle (2h), b is the full width at half maximum intensity (FWHM) in radians [23]. From the Scherer equation the average particle size of Ag NPs is found to be around 22.6 nm which supports the above results obtained from TEM study. In order to confirm the participation of oxidized polyphenols in stabilizing Ag NPs FTIR analysis of purified Ag NPs was carried out and the spectra displayed bands at 3415, 2931, 1624, 1529 and 1400 cm 1 (Fig. 4). The bands at 3415, 2931 and 1624 cm 1 correspond to AOH stretching of phenolic compounds, aromatic ACAH stretching and carboxylic AC@O stretching respectively. The band at 1529 cm 1 is due to ACAC stretching in aromatic ring and band at 1400 cm 1 corresponds to ACAO stretching. Presence of these functional groups indicates the capping of various biomolecules, which interacts with the metal salts through the functional groups and takes parts in reduction followed by stabilization of NPs through capping. It is well known that secondary metabolites present in the form of polyphenols in plants are considered to be natural reducing agents [24]. To identify polyphenols present in M. elengi extract HPLC analysis was carried out by using mobile phase (acetonitrile and KCl mixture) at a flow rate of 1 mL min 1. The chromatogram of M. elengi extract shows 4 different peaks at the retention time (RT) of 2.38, 2.70, 3.12 and 3.85 min which corresponds to ascorbic acid, gallic acid, pyrogallol and resorcinol respectively whereas the

Fig. 5. HPLC chromatograms of M. elengi extracts matched with standards (A) overlay showing the chromatograms of extracts before and after reduction (B).

peak appeared at RT of 2.91 min is not identified (Fig. 5A). Among these identified compounds concentrations of ascorbic acid and gallic acid were found to be more in the extracts and others were comparatively less in concentrations. In order to find out which secondary metabolite was playing a major role in the reduction process HPLC analysis of the extract was carried out before reduction and after reduction. The chromatograms reveal that there was gradual decrease in the peak intensity of both ascorbic acid and gallic acid (Fig. 5B) and hence it is clear that gallic acid is the major constituent involved in the biosynthesis of Ag NPs. Based on the HPLC and FTIR data it is clear that phytochemicals in the extract are multifunctional. The shift in the peak positions of AOH (3400–3415 cm 1) and AC@O (1614–1624 cm 1) before and after reduction confirms the active participation of polyphenols in formation and stabilization of Ag NPs. The hydroxyl groups present in the identified polyphenols helps in the reduction of the silver ions simultaneously the polyphenols under goes oxidation to form their respective quinine forms however from FTIR reports the mechanism between metal ions and polyphenols is not well understood but based on HSAB principle it clear that when hard ligands (hydroxyl groups present in polyphenols/AOH) come in contact

Fig. 4. FTIR spectra of synthesized Ag NPs and plant extract (inset).

H.A. Kiran Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 130 (2014) 13–18

17

Fig. 6. Antibacterial activity of synthesized Ag NPs on S. aureus (A), E. coli (B) and histogram showing zone of inhibition (C).

with soft metal complexation is not favoured instead, soft metal ion undergoes reduction. The hard ligands (AOH) on oxidation forms soft ligands (carbonyl groups in the oxidized polyphenols/ AC@O), which forms the coordination with formed Ag NPs by electrostatic interaction and makes them stable by arresting further growth [24,25]. Antibacterial activity Ag NPs are well known for their antimicrobial activity [26]. In present study Ag NPs showed effective results towards both gram positive and gram negative bacterial cultures. By varying the concentrations of Ag NPs the minimum inhibitory concentration was determined. Different concentrations of Ag NPs varying from 10 lg/mL to 50 lg/mL were used to find out the minimum inhibitory concentration (MIC). The biogenic Ag NPs exhibited virtuous antimicrobial activity against both the bacterial strains and results showed visible and clear zones of inhibition (Fig. 6). 20 lg/mL was found to be MIC for both the bacterial strains. The reported MIC values for S. aureus and E. coli using Ag NPs synthesized from different plant extracts were compared with the present study and listed in Table – S1 (supplementary document) [27–31]. Further the comparison study reveals that size and morphology of the Ag NPs affects the antimicrobial activity of bacterial strains. It is observed that in isotropic forms as the size decreases the MIC values also decreases and activity towards bacterial strains increases while

for anisotropic particles the activity changes steadily due to different shapes which suggests that shape of the NPs plays a vital role in antimicrobial activity (Fig. S1). There is no report found on change in antioxidant properties with change in size and shape of nanoparticles. Synthesized Ag NPs showed higher activity towards S. aureus as compared to E. coli and the zone of inhibitions (ZOI) was measured and shown in Fig. 6C. As the concentrations of Ag NPs increased ZOI also increased, in order to confirm the results all the experiments were done in duplicates. Various mechanisms have been proposed to explain the antibacterial activity of Ag NPs. It is widely accepted that the inhibition is due to damage of cell wall of bacteria caused by Ag NPs. Briefly, Ag NPs incorporated in the cell membrane causes the cell death by damaging the cell membrane by leaking into intracellular substances [32,33]. Hence the synthesized Ag NPs acts as a potential antibacterial agent. Antioxidant activity The antioxidant activity of biosynthesized Ag NPs was evaluated by DPPH assay. In the present study the synthesized Ag NPs showed better activity then the previously reported study [31,34]. The methanolic solution of DPPH was turned from blue to yellow on the addition of Ag NPs which is due to the scavenging of DPPH by donation of hydrogen to form the stable DPPH molecule [31,35]. As the concentration of Ag NPs increased from 20 lg/mL to 100 lg/mL the absorbance at 517 nm was decreased indicating the increase in free radical scavenging activity (Fig. 7). Conclusion Present study reports the simple one step eco-friendly synthesis of Ag NPs using M. elengi extract. The extract acts as both reducing and stabilizing agent which was confirmed by FTIR studies. The identification of phytochemicals and their role in the reduction of Ag+ ions to Ag NPs was examined with the help of HPLC analysis. TEM and XRD reports revealed that synthesized Ag NPs were crystalline in nature with an average particle size of 23.5 nm. This bioinspired Ag NPs were found to be multifunctional with good antibacterial and antioxidant activities. The synthesized Ag NPs were stable for more than 5 months. This bioinspired method facilitates best alternative for both chemical and other physical methods. Hence this method can be employed in large scale production and can be used in many medicinal and technological applications. Acknowledgements

Fig. 7. Antioxidant activity of synthesized Ag NPs as compared to ascorbic acid as standard antioxidant.

The authors are grateful to VIT University, Vellore 632014 for the help and platform given to do this work. We are also highly

18

H.A. Kiran Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 130 (2014) 13–18

thankful to SAS, VIT University for providing the basic characterization facilities and SAIF, IITM for TEM analysis. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.saa.2014.03.024. References [1] C. Krishnaraj, E.G. Jagan, S. Rajasekar, P. Selvakumar, P.T. Kalaichelvan, N. Mohan, Colloids Surf. B: Biointerfaces 76 (2010) 50–56. [2] G. Cao, Nanostructures and Nanomaterial’s: Synthesis, Properties and Applications, Imperial College Press, London, 2004. [3] T.K. Joerger, R. Joerger, E. Olsson, C.G. Granqvist, Trends Biotechnol. 19 (2001) 15–20. [4] S. Kotthaus, B.H. Gunther, R. Hang, H. Schafer, IEEE T. Comp. Pack. A 20 (1997) 15–20. [5] S. Iravani, Green Chem. 13 (2011) 2638–2650. [6] D.G. Yu, Colloids Surf. B: Biointerfaces 59 (2007) 171–178. [7] T. Tsuji, T. Kakita, M. Tsuji, Appl. Surf. Sci. 20 (2003) 314–320. [8] Y.H. Kim, D.K. Lee, B.G. Jo, J.H. Jeong, Y.S. Kang, Colloids Surf. A: Physicochem. Eng. Aspects 284 (2006) 364–368. [9] M. Darroudi, A.K. Zak, M.R. Muhamad, N.M. Huang, M. Hakimi, Mater. Lett. 66 (2012) 117–120. [10] L. Rastogi, J. Arunachalam, Mater. Chem. Phys. 129 (2011) 558–563. [11] R.O. Becker, Metal-Based Drugs 6 (1999) 297–300. [12] I. Willner, R. Baron, B. Willner, Adv. Mater. 18 (2006) 1109–1120. [13] D.S. Bhakuni, M.L. Dhar, M.M. Dhar, B.N. Dhawan, B.B. Mehrotra, Indian J. Exp. Biol. 7 (1969) 250–262. [14] K. Kalishwaralal, V. Deepak, S. Ramkumarpandian, H. Nellaiah, G. Sangiliyandi, Mater. Lett. 62 (2008) 4411–4413.

[15] B. Gopalkrishnan, S.N. Shimpi, Int. J. Pharmacogn. Phytochem. Res. 3 (2010) 13–17. [16] A. Ruikar, R. Torane, A. Tambe, V. Puranik, N. Deshpande, Int. J. Chem. Tech Res. 1 (2009) 158–161. [17] K.M. Hazra, R.N. Roy, S.K. Sen, S. Laskar, Afr. J. Biotechnol. 6 (2007) 1446–1449. [18] R. Deshpande, M.D. Bedre, S. Basavaraja, B. Sawle, S.Y. Manjunath, A. Venkataraman, Colloids Surf. B: Biointerfaces 79 (2010) 235–240. [19] K.L. Kelly, E. Coronado, L.L. Zhao, G.C. Schatz, J. Phys. Chem. B 107 (2003) 668– 677. [20] D. Philip, C. Unni, S.A. Aromal, V.K. Vidhu, Spectrochim. Acta A 78 (2011) 899– 904. [21] W.H. Eisa, Y.K. Abdel-Moneam, Y. Shaaban, A.A. Abdel-Fattah, A.M.A. Zeid, Mater. Chem. Phys. 128 (2011) 109–120. [22] I.A. Wani, A. Ganguly, J. Ahmed, T. Ahmad, Mater. Lett. 65 (2011) 520–522. [23] D.S. Sheny, J. Mathew, D. Philip, Spectrochim. Acta A 79 (2011) 254–262. [24] K. Mohan Kumar, B.K. Mandal, S.K. Tammina, RSC Adv. 3 (2013) 4033–4039. [25] K. Yoosaf, B.I. Ipe, C.H. Suresh, K.G. Thomas, J. Phys. Chem. C 111 (2007) 12839–12847. [26] K.M. Hindi, A.J. Ditto, M.J. Panzner, D.A. Medvetz, D.S. Han, C.E. Hovis, J.K. Hilliard, J.B. Taylor, Y.H. Yun, C.L. Cannon, W.J. Youngs, Biomaterials 30 (2009) 3771–3779. [27] R. Veerasamy, T.Z. Xin, S. Gunasagaran, T.F.W. Xiang, E.F.C. Yang, N. Jeyakumar, S.A. Dhanaraj, J. Saudi Chem. Soc. 15 (2011) 113–120. [28] K. Mohan Kumar, M. Sinha, B.K. Mandal, A.R. Ghosh, K. Siva Kumar, P.S. Reddy, Spectrochim. Acta A 91 (2012) 228–233. [29] A. Saxena, R.M. Tripathi, F. Zafar, P. Singh, Mater. Lett. 67 (2012) 91–94. [30] V. Gopinath, S. Priyadarshini, N. MeeraPriyadharsshini, K. Pandian, P. Velusamy, Mater. Lett. 91 (2013) 224–227. [31] C. Dipankar, S. Murugan, Colloids Surf. B: Biointerfaces 98 (2012) 112–119. [32] I. Sondi, B.S. Sondi, J. Colloid Interface Sci. 275 (2004) 177–182. [33] M. Sathishkumar, K. Sneha, Y.S. Yun, Bioresour. Technol. 101 (2010) 7958– 7965. [34] K.L. Niraimathi, V. Sudha, R. Lavanya, P. Brindha, Colloids Surf. B: Biointerfaces 102 (2013) 288–291. [35] L. Sun, J. Zhang, X. Lu, L. Zhang, Y. Zhang, Food Chem. Toxicol. 49 (2011) 2689– 2696.

Antimicrobial and antioxidant activities of Mimusops elengi seed extract mediated isotropic silver nanoparticles.

The present study reports the use of Mimusops elengi (M. elengi) fruit extract for the synthesis of silver nanoparticles (Ag NPs). The synthesized Ag ...
1MB Sizes 0 Downloads 4 Views