The bio-molecules from various plant components and microbial species have been used as potential agents for the synthesis of silver nanoparticles (AgNPs). In spite of a wide range of bio-molecules assisting in the process, synthesizing stable and widely applicable AgNPs by many researchers still poses a considerable challenge to the researchers. The biological agents for synthesizing AgNPs cover compounds produced naturally in microbes and plants. More than 100 different biological sources for synthesizing AgNPs are reported in the past decade by various authors. Reaction parameters under which the AgNPs were being synthesized hold prominent impact on their size, shape and application. Available published information on AgNPs synthesis, effects of various parameters, characterization techniques, properties and their application are summarised and critically discussed in this review.
Materials in the nano dimensions (1 - 100 nm) have remarkable difference in the properties compared to the same material in the bulk. These differences lie in the physical and structural properties of atoms, molecules and bulk materials of the element due to difference in physiochemical properties and surface to volume ratio [
About 5000 years ago, many Greeks, Romans, Persians and Egyptians used silver in one form or other to store food products [
In the recent past, silver nano particles (AgNps) have received enormous attention of the researchers due to their extraordinary defense against wide range of microorganisms and also due to the appearance of drug resistance against commonly used antibiotics [
Over the past decade, few reviews focusing on green synthesis of AgNPs were published [
The primary requirement of green synthesis of AgNPs is silver metal ion solution and a reducing biological agent. In most of the cases reducing agents or other constituents present in the cells acts as stabilizing and capping agents, so there is no need of adding capping and stabilizing agents from outside.
The Ag+ ions are primary requirement for the synthesis of AgNPs which can be obtained from various water soluble salts of silver. However, the aqueous AgNO3 solution with Ag+ ion concentration range between 0.1 - 10 mm (most commonly 1 mm) has been used by the majority of researchers.
The reducing agents are widely distributed in the biological systems. The AgNPs have been synthesized using different organisms belonging to four kingdom out of five kingdom of living organisms i.e. Monera (prokaryotic organisms without true nucleus) Protista (unicellular organisms with true nucleus), fungi (eukaryotic, saprophyte/parasite), plantae (eukaryotic, autotrophs) and animalia (eukaryotic, heterotrophs). Data are not available regarding use of animal materials for the synthesis of AgNP’ till date to the best of our knowledge. Due to this limitation, green synthesis of AgNPs has been discussed under headings microorganisms, plants, and bio-poly- mers.
Green syntheses of AgNPs have been performed using plant extracts, microbial cell biomass or cell free growth medium and biopolymers. The plants used for AgNps synthesis range from algae to angiosperms; however, limited reports are available for lower plants and the most suitable choice are the angiosperm plants. Parts like leaf, bark, root, and stem have been used for the AgNP synthesis. The medicinally important plants like Boerhaavia diffusa [
The preferred solvent for extracting reducing agents from the plant is water in most of the cases however, there are few reports regarding the use of organic solvents like methanol [
The AgNPs synthesis by microbes is strenuous compared to the use of plant extracts and biopolymers as reducing and capping agents mainly due to the difficulty in growth, culture maintenance, and inoculums size standardization. Several fungal and bacterial species have been successfully used in the synthesis. The AgNPs synthesis mainly followed one of the two distinct routes, one utilizing extracellular materials secreted in the growth medium whereas the other utilizing microbial cell biomass directly. The microbes synthesize AgNP intracellularly as well as extracellularly. The Intracellular synthesis of AgNPs was observed by few researchers [
AgNPs synthesis supports better control on size and shape of AgNPs, due to easy down streaming and larger adaptability to nano systems. However, extracellular AgNP synthesis is been widely reported [
Centrifugation technique is mostly used by researchers to obtain the pellet or powder form of synthesized silver nanoparticles. The AgNPs suspensions were also oven dried to obtain the product in powder form [
Some common characterizations of AgNPs include UV-Vis Spectra, SEM, TEM, FTIR, XRD and EDAX or EDX/EDS. DLS study is mostly used for AgNPs synthesized from bio-polymers rather than plant extracts and microorganisms. Zeta potential values indicate the stability of synthesized AgNPs. Thermo-Gravimetric Analysis (TGA) is used to find the effect of AgNO3 and L-cystine on the organic composition of AgNPs [
The appearance of yellow to slight brownish-yellow color in the colorless solution has been taken as indicative of AgNPs synthesis by almost all the researchers. The SPR peak of the synthesized AgNPs was witnessed in the range of 400 - 450 nm, the significant range for AgNPs [
However, cubic and hexagonal structures were also reported in some cases. EDS or EDAX, for analyzing elemental composition in the nanomaterials, exhibited a characteristic optical absorption band peak around 3 KeV with silver weight percentage ranging from 45% to 80%. The reported stability of synthesized AgNPs has varied from 1 day to 1 year depending upon reducing agents and other operating conditions.
The synthesis of AgNP by biological entities is due to the presence of large number of organic chemical like carbohydrate, fat, proteins, enzymes& coenzymes, phenols flavanoids, terpenoids, alkaloids, gum, etc capable of donating electron for the reduction of Ag+ ions to Ag0. The active ingredient responsible for reduction of Ag+ ions varies depending upon organism/extract used. For nano-transformation of AgNPs, electrons are supposed to be derived from dehydrogenation of acids (ascorbic acid) and alcohols (catechol) in hydrophytes, keto to enol conversions (cyperaquinone, dietchequinone, remirin) in mesophytes or both mechanisms in xerophytes plants [
The major physical and chemical parameters that affect the synthesis of AgNP are reaction temperature, metal ion concentration, extract contents, pH of the reaction mixture, duration of reaction and agitation. Parameters like metal ion concentration, extract composition and reaction period largely affect the size, shape and morphology of the AgNPs [
The Reaction conditions like time of stirring and reaction temperature are important parameters. Temperatures up to 100˚C were used by many researchers for AgNP synthesis using bio-polymers and plant extracts, whereas the use of mesophilic microorganism restricted the reaction temperature to 40˚C. At higher temperatures the mesophilic microorganism dies due to the inactivation of their vital enzymes. The temperature increase (30˚C - 90˚C) resulted in increased rate of AgNPs synthesis [
It has been found that the size range of AgNPs synthesized from algae, bryophytes, pteridophytes, gymnosperms and bio-polymer sources lie below 50 nm and that of AgNPs synthesized using from angiosperms, algae and bacterial sources ranged between 100 nm and more. The reaction mixture synthesizing AgNP using microorganisms and bio-polymers were continuously agitated to protect agglomeration compared to plant extracts without any suitable reason by the authors. Reaction mixture agitation achieved by applying external mechanical force might accelerate the formation of nanoparticles. Aging of the synthesized AgNP solution changed spherical nanoparticles into flower like structure [
The recent research results have shown that the AgNPs, due to their special characteristics, have immense potential for applications as anti-microbial, anti-parasitic and anti-fouling agents; as agents for site-specific medication, water purification systems, etc. The essential features of some of these applications are discussed in the following sections.
The AgNPs have been found to exhibit promising anti-micribial activity. Researchers have used several novel techniques to confirm and quantify the anti-micribial activity of AgNPs.
The disc diffusion method, a most commonly used technique to access the antimicrobial activity of a liquid, has been employed by many researchers to confirm antimicrobial action of the AgNPs solution. In this method, uniform sized disc of adsorbent material are dipped in the increasing concentration of AgNP and placed over surface of the targeted microbe inoculated on the nutrient medium plates. An inhibition zone formation around the disc reflects antimicrobial action of the nanomaterials [
S. No. | Author | Reducing Agent | Operating Conditions | Characterization | Particle Characteristics | Remarks |
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Algae | ||||||
1 | Kathiraven et al. (2014) [ | Filtered aqueous extract of Caulerpa racemosa marine algae | AgNO3 concentration―1 mM, Reaction period―3 hr, Reaction temp―room temp. Extract: 10 ml/90 ml (AgNO3), Motion: static | UV-Vis FTIR TEM XRD | Size―5 - 25 nm Shape―sph, tri. Structure―FCC | Antibacterial action against P. mirabilis and S. aureus |
2 | Rajesh et al. (2012) [ | Ethyl acetate extract of Ulva fasciata | 1 mM, 2 min, room temp. 3 ml/100 ml, Static | UV-Vis FTIR SEM XRD EDX | Size―28 - 41 nm Shape―sph Structure―cryst Nature―PD | Antibacterial action against X. campestrispv malvacearum pathogen |
3 | Vivek et al. (2011) [ | Aqueous filtrate of Gelidiella acerosa | 1 mM, room temp, 10 ml/90 ml, Agitated | UV-Vis FTIR SEM TEM XRD | Size―~22 nm Shape―sph. Structure―FCC Nature―PD | Antifungal against Mucor inicus and Trichoderma reesei |
4 | Govindaraju et al. (2009) [ | Aqueous filtrate of Sargassum wightii | 1 mM, 1 hr, room temp, 10 ml/90 ml, Static | UV-Vis FTIR TEM XRD | Size―8 - 27 nm Shape―sph/variable Structure―cryst | Antibacterial against S. aureus, B. rhizoids, E. coli and P. aeruginosa |
Bryophyte | ||||||
5 | Kulkarni et al. (2012) [ | Ethanol filtrate of Riccia | 1 mM, 25˚C, dark, 5 ml/1 ml, Agitated | UV-Vis SEM EDS | Shape―cub/triang | Antibacterial against p. aeruginosa |
6 | Kulkarni et al. (2012) [ | Ethanol filtrate of Anthoceras | 0.5 mM, 10 min, room temp. 5ml/1 ml, Static | UV-Vis SEM EDS | Size―20 - 50 nm Shape―cub/triang | Antibacterial activity after incorporation into gauze cloth |
7 | Srivastava et al. (2011) [ | Aqueous and ethanol filtrate of Fissidens minutes | 0.5 mM, 1 hr, room temp. 10 ml/1 ml, Shaken | UV-Vis SEM EDS | Shape―nearly sph | Antibacterial action against E. coli, B. cereus, K. pneumoniae, P. aeruginosa |
8 | Kulkarni et al. (2011) [ | Aqueous filtrate of Anthoceras | 1 mM, 25˚C, dark, 5 ml/1 ml, Agitated | UV-Vis SEM EDS | Size―20 - 50 nm Shape―cub/triang | Antibacterial action against E. coli, B. subtilis, K. pneumoniae, P. aeruginosa |
Pteridophyte | ||||||
9 | John De Britto et al. (2014) [ | Aqueous filtrate of Pteris argyreae, Pteris confuse and Pteris blaurita | 1 mM, 28 hr, room temp. 5 ml/100 ml, Static, Centrifugation: 25 min at 10000 rpm. | Antibacterial action against Shigella boydii, Shigella dysenteriae, S. aureus, Klebsiella vulgaris and Salmonalla typhi | ||
10 | Bhor et al. (2014) [ | Aqueous filtrate of Nephrolepis sexaltata L. fern | 1mM, 4h, 10 ml/90 ml | UV-Vis SEM XRD | Size―avg 24.76 nm Shape―sph. Structure―FCC | Antibacterial against many human and plant pathogens |
11 | Sant et al. (2013) [ | Aqueous filtrate of Adiantum philippense L. | 1 - 10 mM, 30˚C Extract: AgNO3 Ratio-1: 10; 1:100; 1:1000, Agitated | UV-Vis FTIR EDS TEM DLS XRD | Size―10 - 18 nm Shape―anisotropic Structure―FCC Nature―MD | AgNps from medicinally important plants opens spectrum of medical applications. |
12 | Nalwade et al. (2013) [ | Aqueous filtrate of Cheilanthes forinosa Forsk leaf | 1 mM, 4 hr, room temp. 10 ml/90 ml | UV-Vis SEM XRD | Size―~26.58 nm Shape―sph. Structure―FCC | Antibacterial action against S. aureus and Proteus morgani |
13 | Kang et al. (2008) [ | Aqueous filtrate of Pteridophyta | 1 mM, 12 hr, room temp. 10 ml/100 ml, Static | UV-Vis TEM EDX | Size―20 - 30 nm Shape―sph. | AgNps are stable for 12 months. |
Gymnosperms | ||||||
14 | Jha and Prasad. (2010) [ | Filtered aqueous-ethanol extract of Cycas leaf | 0.25 M, 10min, room temp. 80 ml/20 ml, Static | UV-Vis TEM XRD | Size―2 - 6 nm Shape―sph. Structure―FCC | The extraction of cycas leaf is done in 50% EtOH as solvent. |
15 | Song and Kim. (2009) [ | Decanted aqueous extract of Pinus desiflora and Ginko biloba leaf | 0.1 - 2 mm, 30 min, 25˚C - 95˚C, 10 ml/190 ml, Static, 20 min (15k rpm) | UV-Vis SEM TEM EDS ICP | Size―15 - 500 nm Shape―sph. Structure―cryst | AgNps were stable for 4 weeks. |
Angiosperms | ||||||
16 | Ashokkumar et al. (2015) [ | Filtered aqueous extract of Abutilon indicum leaf | 10 mm, 15 min, room temp. 2 to 3.5 ml/30 ml, Static | UV-Vis FTIR FE-SEM TEM XRD FS | Size―7 - 17 nm Shape―sph. Structure―FCC | Antimicrobial action against S. typhi, E. coli, S. aureus, B. substilus |
17 | Sadeghi et al. (2015) [ | Filtered aqueous-methanol extract of Pistacia atlantica seed powder. | 1 mM, 35 min, room temp. 1 ml/10 ml, Shaken,15 min at10 k rpm | UV-Vis FTIR SEM TEM XRD EDAX ZP | Size―10 - 50 nm Shape―sph. Structure―FCC | Stability: 7 - 11 pH range. Antibacterial affect against S. aureus. |
18 | Sadeghi and Gholamhoseinpoor (2015) [ | Methanol extracted aqueous filtrate of Ziziphora tenuior leaf | 0.1 mM, 35 min, room temp. Static, Oven dried | UV-Vis FTIR SEM-EDAX TEM XRD ZP | Size―8 - 40 nm. Shape―sph. Structure―FCC | Stability: 6 - 12 pH range |
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19 | Ajitha et al. (2014) [ | Filtered aqueous extract of Tephrosia purpurea leaf powder | 1 mM, 5 min, 37˚C, 10 ml/50 ml, Stirred,10 min at 10000 rpm | UV-Vis FTIR FESEM TEM XRD EDAX FS RS | Size―~20 nm Shape―sph. Structure―FCC | Antimicrobial agents against Pseudomonas spp. and Penicillium spp. |
20 | Suresh et al. (2014) [ | Filtered aqueous extract of Delphinium denudatum root powder | 1 mM, 2hr, room temp. 1.5 ml/30 ml, Static, 20 min at 12000 rpm | UV-Vis FTIR FESEM XRD | Size―<85 nm Shape―sph. Structure―FCC Nature―PD | Anti-bacterial against S. aureus, B. cereus, E. coli and P. aeruginos Larvicidal to Aedes aegypti |
21 | Rahimi-Nasrabadi et al. (2014) [ | Methanol extract and essential oil of Eucalyptus leucoxylon leaf | 120 min, room temp. Static | UV-Vis SEM TEM XRD | Size―~50 nm Shape―sph. Structure―FCC | AgNP with biomedical potential |
22 | Zuas et al. (2014) [ | Filtered aqueous extract of Myrmecodia pendan plant. | 2.5 mM, room temp. 0.3 ml/60 ml, Static | UV-Vis FTIR SEM TEM XRD | Size―10 - 20 nm Shape―sph. Structure―FCC | Promising therapeutic value |
23 | Mondal et al. (2014) [ | Saline washed, filtered aqueous extract of Parthenium hysterophorous root | 10 mM, 24 hr, room temp. 1:3 to 1:9, Static | UV-Vis FTIR SEM | Shape―spherical | Potential larvacidal for Culex quinquefasciatus |
24 | Raut et al. (2014) [ | Filtered aqueous extract of Withania somnifera leaf powder. | 100 mM, sunlight: 5min, dark room: 12hr, room temp. 100 ml/1 ml, Static | UV-Vis FTIR TEM XRD EDAX | Size―5 - 30 nm Shape―sph. Structure―FCC | AgNPs with quasi-reversible redox behavior Anti-bacterial to E. coli and S. aureus Anti-fungal to A. niger, A. flavus and C. albican |
25 | Vijaykumar et al. (2014) [ | Aqueous extract of Boerhaavia diffusa plant powder. | 0.1 mm, 24 hr, 100˚C, 10 ml/90 ml, Stirred | UV-Vis FTIR SEM-EDAX XRD TEM | Size―~25 nm Shape―sph. Structure―FCC, Cub | Antibacterial to fish pathogens A. hydrophilia, F. branchiophilum, P. fluorescens |
26 | Ajitha et al. (2014) [ | Aqueous extract of Plectranthus amboinicus leaf | 1 mM, 5 min, room temp. 20 ml/50 ml, Stirred, 10 min at 10000 rpm | UV-Vis FTIR FESEM TEM XRD EDAX RS | Size―~20 nm Shape―sph. Structure―FCC | Antimicrobial agents against E. coli and Penicillium spp. |
27 | Singh et al. (2015) [ | Lantana camara | UV-Vis FTIR FESEM | 48.1 nm | Anti microbial to E coli and S. aureus Leakage due to cell wall rupturing | |
28 | Rao et al. (2014) [ | Decanted aqueous filtrate of lemon | 1 - 5 mM, room temp and 40˚C, dark 10 ml/50 ml, pH―3 - 10, Stirred | UV-Vis SEM AFM | Size―~75 nm Shape―small grains | SDS is added for stability. Antibacterial action to E. coli and B. subtilis |
29 | Vimala et al. (2015) [ | Leaf and fruit of Couroupita guianensis | FTIR XRD TEM | Cubic size 10-45 nm 5―15 nm | water soluble phenolic compounds as reducing and stabilizing agent larvicidal to A. aegyptiextensive mortality rate ( LC90~5.65 ppm) | |
30 | Shafaghat (2014) [ | Vacuo evaporated methanol extract of Viburnum lantana leaf | 500 mM, 4 hr, 25˚C, 5 g/100 ml, Stirred, 30 min at 3000 rpm | UV-Vis XRD TEM FTIR SEM | Size―20 - 80 nm Shape―sph Structure―FCC Nature―uniform | Antibacterial to variousgram positive and gram negative species |
31 | Elumalai et al. (2014) [ | Filtered coconut water | 1 mM, 15 min, 80˚C, 10 ml/90 ml, Static, 20 min at 18000 rpm | UV-Vis XRD SEM EDAX FTIR | Size―70 - 80 nm Structure―FCC Nature―PD | Metabolites and proteins served as capping agents. |
32 | Roopan et al. (2013) [ | Filtered aqueous extract of mesocrap layer of Cocos nucifera | 1 mM, 1 hr, 60˚C, 20 ml/80 ml, Stirring, pH―2 - 11 | UV-Vis TEM XRD | Size―24 nm. Shape―sph. Structure―FCC | Larvicidal nature |
33 | Anuj and Ishnava (2013) [ | Filtered aqueous extract of Tinospora cordifolia stem powder. | 1 mM, 30 min, room temp. 40 ml/200 ml, 15 min at 10000 rpm, Stirring | UV-Vis FTIR TEM XRD EDAX | Size―60 nm. Shape―sph. Structure―cryst | Antibacterial nature |
34 | Zhang et al. (2013) [ | Filtered aqueous extract of Aloe leaf | 0.1 - 1.5 mM, 20 min, 20˚C - 40˚C, 0 to 15 ml/1 ml, Hydrazine hydrate content: 1 to 15 ml, Static | UV-Vis TEM XRD | Size―~20 nm. Shape―sph. Structure―FCC | Antibacterial to E. coli and S. aureus |
35 | Yang et al. (2013) [ | Filtered aqueous extract of Mangifera indica linn peel | 0.5 to 4 mM, 15 to 90 min, 25 to 100˚C, 0.1 to3 ml/27 ml, pH: 2 - 11. Static | UV-Vis TEM XRD | Size―7 - 27 nm Shape―sph. Structure―FCC | Stable for 3 months, AgNPs loaded on fabrics exhibited antimicrobial property. |
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36 | Jagtap and Bapat. (2013) [ | Filtered aqueous extract of Artocarpus heterophyllus lam. Seed powder | 2 to 10 mM, 5 min, 121˚C, 15 psi. 2 to 10 w/v%, 1:4, Static, 15min at 10000 rpm | UV-Vis FTIR SEM-EDAX TEM | Size―3 - 25 nm Shape―irregular | Anti-bacterial to B. cereus, B. subtilis, S. aureus and P. aeruginosa. AgNP-lectin hybrid has promising use in glycol nanosensors for disease diagnosis. |
37 | Khalil et al. (2013) [ | Filtered aqueous extract of olive leaf | 1 mM, 2 min, 30˚C to 90˚C, 0.5 to 5 ml/10 ml, pH: 2 ? 11, Stirred | UV-Vis FTIR SEM TEM XRD TGA | Size―20 - 25 nm Shape―sph. Structure―FCC | Stability: 1 week, AgNPs inhibited growth of E. coli, S. aureus and P. aeruginosa |
38 | Karuppiah and Rajmohan (2013) [ | Filtered aqueous extract of Lxora coccinea L. leaf | 1 mM, dark and room temp. 0.5 ml/10 ml, 15 min at 10000 rpm, Static | UV-Vis FTIR. FE-SEM XRD | Size―13 - 57 nm Shape―sph. Structure―FCC | |
39 | Logeswari et al. (2013) [ | Filtered ethanolic extracts of Solanum tricobactum, syzygium cumini, centella asiatica and citrus sinensis plant powders | 1 mM, 24 - 48 hr, 37˚C, 10 ml/5 ml, Additive: ammonium solution= 2.5 ml, agitated | UV-Vis FTIR XRD AFM | Size―41 - 53 nm. Shape―irregular Structure―FCC | Antibacterial against pathogenic P. aeruginosa |
40 | Geetha lakshmi and Sarada (2013) [ | Sponin extracted from Trianthema decendra L. | 1 mM, dark and incubated, 1 ml/5 ml, Static, 15min at 10000 rpm | UV-Vis FTIR FE-SEM EDAX | Size―17.9 - 59.6 nm. Shape―sph. | Antibacterial to P. aeruginosa, E. faecalis, S. typhi, K. pneumonia, E. coli and C. albicans |
41 | Yasin et al. (2013) [ | Filtered aqueous extract of Bamboo leaf | 3 mM, 65˚C, 5 ml/5 ml, Stirring | UV-Vis TEM XRD EDX | Size―13 ± 3.5 nm Shape―nearly sph. Structure―cryst | Antibacterial to E. coli and S. aureus |
42 | Rodriguez-Leon et al. (2013) [ | Ethanol/aqueous extract of Rumex hymenosepalus root | 2.5 - 15 mM, 24 - 96 hr, room temp. 5% v/v, Static | UV-Vis TEM EDS | Size―2 - 40 nm cub and hex Structure―FCC | AgNPs are synthesized in ethanol medium. |
43 | Rajathi and Sridhar (2013) [ | Decanted aqueous filtrate of Wrightia tinctoria leaf | 1 mM, 2 hr, room temp. 0.5 ml/10 ml, Static, 10 min at 10000 rpm | UV-Vis FTIR XRD | Size―5 - 20.5 nm Structure―cryst | Antibacterial to S. aureus, V. cholerae, M. luteus and K. pneumonia |
44 | Kannan et al. (2013) [ | Filtered aqueous extract of codium captium sea weed powder. | 1 mM, 48 hr, room temp, dark, 12ml/1 ml, Static, 20 min at 12000 rpm | UV-Vis FTIR SEM-EDAX TEM | Size―3 - 44 nm Nature―nano- clusters | Fresh extract was more potent for AgNP synthesis. |
45 | Natarajan et al. (2013) [ | Powdered Elaeagnus indica leaves | 0.5 - 2 mM, 20 - 60 min, 40˚C - 100˚C, 10 g/3 ml, Static, 10 min at 12000 rpm | UV-Vis FTIR TEM DLS | Size―avg 30 nm Shape―sph. Nature―MD | Antimicrobial against E.coli, P. putida, B. subtilis, S. aureus, A. flavus and F. oxysporum |
46 | Kirubaharan et al. (2012) [ | Filtered aqueous extract of Azadirchata indica(neem) leaves | 1 mM, 90 min, room to 90˚C, 1.25 ml/50 ml, pH: 6 - 8. Stirred | UV-Vis TEM XRD | Size―15 - 20 nm Shape―sph. Structure―FCC Nature―MD, PD | Stability: 4 months, Heavy metal ion sensors in aqueous media |
47 | Satishkumar et al. (2012) [ | Filtered aqueous extract of Morinda citifolia L. leaf powder | 1 mM, 0 - 60 min, 37˚C - 100˚C, 5 ml/95 ml, 5 min at 5000 rpm, Static | UV-Vis FTIR SEM HR-TEM | Size―10 - 60 nm Shape―sph. Structure―FCC | Stability 1 month, Inhibitory to human pathogens like E. coli, P. aeroginosa, K. pneumoniae, B. cereus, Enterococci spp. and Enterobacter aerogenes |
48 | Edison and Sethuraman. (2012) [ | Filtered aqueous extract of Terminalia chebula fruit powder. | 10 mM, room temp. 1 ml/25 ml, pH: 4 ? 9, Static | UV-Vis FTIR HR-TEM XRD EDS DLS ZP | Size―25 nm Structure―FCC Nature―phyto capped | Stabile for 10 days, AgNps showed catalytic activity on the reduction of methylene blue. |
49 | Kaviya et al. (2012) [ | Aqueous filtrate of Crossandra infundibuliformis leaf | 1 mM, 1 hr, room temp, 3 ml/40 ml, Stirring, 20 min at 4000 rpm | UV-Vis. FTIR FESEM-EDAX XRD | Size―~38 nm Shape―flake Structure―-FCC | |
50 | Gopinath et al. (2012) [ | Filtered aqueous extract of Tribulus terrestris L dried fruit | 1 mM, room temp, dark, 100 ml/150 ml, Static | UV-Vis FTIR TEM XRD AFM | Size-16-28 nm Shape-sph. Structure-FCC. | Stability-6 months. Antibacterial to S. pyogens, P. aeruginosa, E. coli, S. aureus and B. subtilis |
51 | Vijayaraghavan et al. (2012) [ | Filtered aqueous extract of Trachyspermum ammi and Papavera somniferum plant powders | 1 mM, Trachyspermum ammi: 15 min, Papavera somniferum: 35 min, 28˚C, 1 ml/50 ml, Shaking | UV-Vis SEM-EDAX | Trachyspermum ammi: Size―87 - 998 nm Shape―tri Papavera somniferum: Size―3.2 - 7.6 µm Shape―sph. | Essential oil in T. ammi was found to be good reducing agent when compared to alkaloids in P. somniferum. |
52 | Sreekanth et al. (2012) [ | Dioscorea batatas rhizome powder | 1 mM, 25 and 80˚C Static, 20 min at 5000 rpm | UV-Vis FTIR SEM XRD | Shape―circular and flower Structure―FCC Nature―MD | |
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53 | Chaudhary et al. (2012) [ | Aqueous filtrate of Vitis viniera fruit | 1 mM, 10 hr, room temp. 10 ml/90 ml, Static.15 min at 2000 rpm | UV-Vis SEM XRD | Size―10 - 880 nm Shape―sph Structure―FCC, cubic and hexl | Antibacterial to B. subtilis, E. coli, P. aeruginosa and S. pnemoniae |
54 | Ashok kumar (2012) [ | Aqueous filtrate of Prathemium hysterophorus plant | 1 mM, 24 hr, room temp. 1 ml/9 ml, Static, 20 min at 5000 rpm | UV-Vis FTIR SEM XRD | Size―avg 10 nm Shape―nearly sph Structure―FCC | |
55 | Patil et al. (2012) [ | Filtered aqueous extract of Ocimum tenuiflorum leaf | 1 mM, 10 min, room temp. 2 ml/20 ml, Static | UV-Vis TEM PS ZP | Size―15-25 nm Shape-sph Structure―FCC | Antibacterial against E. coli, C. bacterium, B. subtilis |
Arunachalam et al. (2013) [ | Indigofera aspalathoides, aqueos leaf t extracts | UV Vis SEM EDAX FTIR | Size―20 - 50 nm | Water-soluble organics leaf extract responsible to reduction. Wound healing applications | ||
56 | Mubarakali et al. (2011) [ | Filtered aqueous extract of Mentha piperita plant powder | 1 mM, 24 hr, 28˚C, 1.5 ml/30 ml, Static, 10 min at 6000 rpm | UV-Vis FTIR SEM EDS | Size―90 nm Shape―sph. | Active against clinically isolated human pathogens like E. coli and S. aureus. |
57 | Mukunthan et al. (2011) [ | Aqueous extract of Catharanthus roseus leaf | 1 mM, 15 min, 80˚C, 10 ml/90 ml, Static | UV-Vis SEM XRD EDAX | Size―48 - 67 nm Structure―FCC Nature―uniform | Antibacterial activity against S. aureus, E. coli, K. pneumoniae, B. aureus and P. aeruginosa |
58 | Rajakumar and Abdul Rahuman (2011) [ | Filtered aqueous extract of Eclipta prostrate leaf | 1 mM, 1 hr, room temp. 12 ml/88 ml, 45 min at 10000 rpm, Static | UV-Vis FTIR SEM TEM XRD | Size―35 - 60 nm Shape―TEM: sph. SEM: triang, hex and pentagon Structure― crystalline Nature―biphasic | Stabile for 6 hr Larvicidal to filariasis vector C. quinquefasciatus and malarial vector A. subpictus |
59 | Kumar and Yadav. (2011) [ | Filtered aqueous extract of Lonicera japonica L leaf. | 1 to 9 mM, 24 hr, 40˚C - 80˚C, 5% to 40% (v/v), Static, 5 min at 10000 rpm | UV-Vis FTIR SEM TEM AFM ZP | Size―36 - 72 nm Shape―sph, plate, and other shaped | Stability: zeta potential―41mV |
60 | Gnanadesigan et al. (2011) [ | Filtered aqueous extract of Rizophora mucronata leaf | 1 M, 10 min, room temp. 10 ml/90 ml, 20 min at 12000 rpm, Static | UV-Vis FTIR XRD AFM | Size―60 - 95 nm Shape―sph. Structure―cryst | Larvicidal to Ae. aegypti and Cx. quinquefasciatus |
61 | Rani and Reddy (2011) [ | Decanted aqueous extract of Piper betel L. leaf | 1 mM, 1 min to 2 hr, room temp, sunlight, 10 ml/190 ml, Static, 15min at 6000 rpm. | UV-Vis FTIR TEM XRD | Sunlight: 5min. Size―~120 nm Shape―irregular Structure―FCC Nature― agglomerated Sunlight: 10 - 80 min Size―28 - 17 nm Shape―sph. Structure―FCC Nature―shelled AgNP | AgNP toxic to aquatic plant D. magna. Biosynthesized AgNP less toxic compared to chemically synthesized ones |
62 | Veerasamy et al. (2011) [ | Aqueous filtrate of Garcinia mangostana leaf | 0.25 - 5 mM, 0 - 70 min, 37˚C - 90˚C, 5 ml/95 ml, Static, pH―4, 7, 8 30 min (5k rpm) | UV-Vis FTIR TEM | Size―avg 35 nm Shape―sph | Stable for 30 days, Antibacterial against E. coli and S. aureus |
63 | Santoshkumar et al. (2011) [ | Decanted aqueous filtrate of Nelumbo nucifera leaf | 1 mM, 10 min, room temp. 12 ml/8 ml, Static | UV-Vis FTIR TEM XRD | Size―25 - 80 nm Shape―sph, tri and dec Structure―FCC | Larvicidal against A. subpictus and C. quinquefasciatus |
64 | Ahmad et al. (2011) [ | Aqueous extract of Desmodium triflorum | 0.025 M, 1 hr | UV-Vis TEM XRD | Size―5 - 20 nm Structure―cryst | Antibacterial against S. spp, E. coli, B. subtilis |
65 | Prathna et al. (2011) [ | Filtered and centrifuged juice of Citruslimon fruit | 0.1 - 10 mM, 4 hr, 30˚C, 1:4 to 4:1, Shaken, 10 min at 10000 rpm | UV-Vis XRD TEM FTIR AFM DLS ZP | Size―~50 nm Shape―nearly sph. Structure―cryst Nature―PD | AgNPs were stable for 14 days. Size-XRD-18.306 nm AFM―<100 nm TEM―25 - 50 nm DLS―153.68 nm |
66 | Bankar et al (2010) [ | Acetone treated, aqueous extracted, filtered and precipitated powder of Banana peel | 0.125 to 1mM, 3 min, 40˚C to 100˚C, 0.5 to 10 mg/2 ml, pH: 2 ? 5, Static | UV-Vis FTIR. SEM-EDS XRD | Size―< 100 nm Structure―FCC | Antifungal and antibacterial action |
67 | Njagi et al. (2010) [ | Filtered aqueous extract of Sorghum bran | 0.1 M, 1min, room temp. 2:1 volume ratio, Shaken | UV-Vis FE-SEM HR-TEM-EDS XRD | Size―10 nm Shape―sph. Structure―FCC Nature―uniform nano clusters | AgNP of smaller size at 50˚C of extraction temperature compared to 25˚C and 80˚C |
68 | Kumar et al. (2010) [ | Filtered aqueous extract of Syzygium cumini leaf (LE) and seed (SE) powder | 1 mM, 24 hr, room temp. 10% (v/v), Static, 20 min, 12k rpm | UV-Vis FTIR SEM AFM | Size―LE: 30nm, Water content of LE: 29 nm, SE: 92 nm, Water content of LE: 73nm. | SE have higher synthesis rates and larger size AgNP compared to LE. |
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69 | Dubey et al. (2010) [ | Filtered aqueous extract of Tanaetum vulgare fruit. | 1 - 3 mM, 10 min - 5hr, 25˚C - 150˚C, 0.5 - 4.8 ml/50 ml, pH: 2 - 10, Static | UV-Vis FTIR TEM XRD EDAX | Size―10 - 40 nm Shape―sph. Structure―FCC | AgNP more stable in basic compared to acidic medium |
70 | Shukla et al. (2010) [ | Filtered aqueous extract of Piper nigrum (black pepper) | 10 mM, room temp. 1 ml/100 ml, Stirred, 10 min at 3000 rpm | UV-Vis TEM XRD | Size―20 - 50 nm Shape―sph. Structure―FCC Nature―large grain, WD, uniform and polycrystalline | |
71 | Krishnaraj et al. (2010) [ | Aqueous filtrate of Acalypha indica leaf | 1 mM, 30 min, 37˚C, dark 12 ml/100 ml, Static, 30 min at 75000 g | UV-Vis SEM TEM EDS XRD | Size―20 - 30 nm Structure―cub | Antimicrobial against water borne pathogens E. coli and Vibrio cholera |
72 | Satish kumar et al. (2009) [ | Aqueous bark and powder extracts of Cinnamon zeylanicum plant | 1 mM, 25˚C, 1 to 5 ml/50 ml, Powder content: 0.1 to 1 g/50 ml, pH: 1 - 11, Shaken | UV-Vis TEM XRD EDX | Size―powder: 31 nm, Extract: 40 nm Shape―quasi sph and R, Structure― cub and hex Nature―bi-phasic | Stable for 3 months, Served as antimicrobial agents |
73 | Tripathi et al. (2009) [ | Aqueous filtrate of Azadirachta indica leaves | 10 mM, 24 hr, 28˚C, 1:4. 15 min at 10,000 rpm Shaken | UV-Vis TEM SEM FTIR | Size―50 - 100 nm Shape―irregular Nature―PD | AgNPs loaded on cotton disks shown antibacterial activity. |
74 | Leela and Vivekanandan. (2008) [ | Aqueous extract of Helianthus annus plant | UV-Vis XRD SEM | Structure-cryst | ||
75 | Chandran et al. (2006) [ | Aqueous extract of Aloe vera leaf | 1 mM, 24 hr, room temp. 5 ml/5 ml, Static | UV-Vis XRD TEM | Size―15.2 ± 4.2 nm Shape―sph. Structure―FCC | |
76 | Ankamwar et al. (2005) [ | Emblica Officinalis fruit extract | UV-Vis TEM | Size―10 - 20 nm | Transmetallation reaction promoted the AgNPs synthesis | |
77 | Shankar et al. (2004) [ | Decanted aqueous extract of Azadirachta indica leaf | 1 mM, 24 hr 5 ml/45 ml, 15 min at 10000 rpm. Static | UV-Vis XRD TEM FTIR | Size―5 - 35 nm Shape―Sph Structure―cryst Nature―PD | AgNPs stable for 4 weeks |
78 | Shankar et al. (2003) [ | Decanted aqueous broth of Pelargonium graveolens leaf | 1 mM, 24 hr 5 ml/100 ml, 15 min at 10000 rpm. Static | UV-Vis XRD FTIR TEM EDAX | Size―16 - 20 nm. Shape―nearly sph Structure―FCC Nature―PD | Chlorophyll of leaf extract formed 5 nm capping around the AgNP. |
Fungi | ||||||
79 | Das et al. (2012) [ | Mycelia of Rhizopus oryzae | 1 to 5 mM, 72 hr, 30˚C, 0.2 g/25 ml. pH―2 to 8, Shaken | UV-Vis FTIR HRTEM EDAX | Size―~15 nm Shape―sph. Structure―FCC | Stable for 3 months, Antimicrobial to E. coli and B. subtilis, Used for treating contaminated water and adsorption of pesticides |
80 | Naveen et al (2010) [ | Aqueous cell filtrate of Penicillium Sp. fungi | 1 mM, 24 hr, room temp, dark 50 ml/50 ml, Agitated, Lyophilized | UV-Vis FTIR AFM | Size―52 - 104 nm | |
81 | Balaji et al (2009) [ | Cladosporium clado sporioides fungal aqueous filtrate | 78 h, 27˚C. 10 ml, Shaken | UV-Vis TEM XRD FTIR | Size―Avg: 35 nm Shape―Sph. Structure―FCC Nature―PD | |
82 | Shaligram et al (2009) [ | Penicillium brevicompatum WA 2315 fungal aqueous filtrate | 1 mM, 72 hr, 25˚C, Shaken | UV-Vis FTIR TEM XRD | Size―58.35 ± 17.8 nm Structure―FCC | |
83 | Fayaz et al. (2009) [ | Harvested cell aqueous filtrate of Trichoderma viride fungus | 1 mM, dark, 10˚C - 40˚C. Shaken. | UV-Vis XRD TEM FTIR | 10˚C: 2 - 4 nm, sph. 27˚C: 10 - 40 nm, sph. 40˚C: 80 - 100 nm, Plate like, Structure: Cryst, Nature: MD | Increase in temperature led to blue shift in UV-Vis peak, decreased size and increased dispersity |
84 | Kathiresan et al. (2009) [ | Aqueous Cell filtrate of Penicillum fellutanum fungus | 0.5 - 2.5 mM, 0 - 48 hr, 0˚C - 40˚C, dark, pH: 5 - 7.5. Salinity-1% - 5% NaCl, Shaken | UV-Vis TEM | Size―5 -2 5 nm Shape―Sph. | (NH4)2SO4 solid used for precipitation and phosphate buffer (pH-8) for dissolution of nanoparticles |
85 | Ingle et al (2009) [ | Aqueous cell filtrate of Fusarium solani fungus | 1mM, room temp. Static, 10 min, 10000 g | UV-Vis FTIR TEM | Size―5 - 35 nm Shape―Sph. | |
86 | Basavaraja et al (2008) [ | Aqueous filtrate of Fusarium semitetum fungus | 1 mM, 48 hr, 27˚C, Shaken | UV-Vis XRD TEM FTIR | Size―10 - 60 nm Shape―Sph. Structure―cryst Nature―PD | AgNP stable for 6 - 8 weeks |
87 | Vigneswaran et al. [ | Asphergillus flavus fungal cells | 1 mM, 24 hr, 37˚C, Dark. 5 g/100 ml, Shaken | UV-Vis TEM XRD FTIR FS | Size―8.92 ± 1.61 nm Shape―Isotropic Structure―FCC Nature―MD | AgNP stable for 3 months |
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88 | Bhainsa and D’souza (2006) [ | Aspherillus fumigates aqueous cell filtrate | 1 mM, 1 hr, 25˚C, Dark, Shaken | UV―Vis TEM XRD | Size―5 - 25 nm Shape―Sph and Tri. Structure―Crystal Nature―WD | No precipitation of AgNP observed upto 72 hrs |
89 | Vigneswaran et al. [ | Phaenerochaete chrysosporium mycelium | 1 mM, 24 hr, 37˚C, Dark, Shaken | UV-Vis XRD SEM TEM FS | Size―50 - 200 nm Shape―sph. and hex. Structure―FCC Nature―non uniform | AgNP formed on the surface of mycelium |
90 | Duran et al (2005) [ | Aqueous filtrate and biomass of Fusarium oxysporum species. | 1 mM, 28 hr, 28˚C. 10 g/100 ml Static. | UV-Vis SEM | Size―20 - 50 nm Shape―sph. | Nitrate based reductase promoted the AgNP synthesis |
91 | Senapati et al. (2004) [ | Verticillium and F. oxysporum | UV-Vis SEM/TEM | Size―Verticillium 25 ± 8 nm, F. oxysporum―5 - 50 nm | Verticillium (intracellular) and F. oxysporum―extracellular synthesis. | |
92 | Ahmad et al. (2003) [ | Fusarium oxysporum biomass | 1 mM, 72 hr, room temp, dark 10 g/100 ml, Static | UV-Vis XRD TEM FTIR FS | Size―5 - 50 nm Shape―sph/tri. Structure―FCC | |
93 | Mukherjee et al. (2001) [ | Harvested mycelia of Verticillium sp. fungi | 0.2 mM, 72 hr, 28˚C, 10 g/100 ml, Shaken, pH: 5.5 - 6 | UV-Vis SEM TEM EDAX | Size―25 ± 12 nm Shape―nearly sph, Nature― monodispersed | AgNPs were synthesized on intracellular bases. |
Gram positive Bacteria | ||||||
94 | Zhang et al. (2014) [ | Lactobacillus fermentum.LMG 8900 cells | 10 g/L, 24 hr, 30˚C, 10 g/L, Shaken, 6 min at 5000 rpm and 10 min at 6000 rpm | UV-Vis TEM XRD ZP | Size―~6 nm Shape―sph. Structure―FCC | Stable for 3 months. Resist growth of E. coli, S. aureus and P. aeruginosa Act as promising anti-biofouling agent |
95 | Zonnoz and Salouti (2011) [ | Aqueous cell filtrate of Streptomyces sp. ERI-3 | 1 mM, 48 hr, 28˚C. Dark. Shaken. | UV-Vis XRD TEM SEM | Size―10 - 100 nm Shape―Spherical | After 3 months, nanoparticles developed floret shape |
96 | Deepak et al. (2011) [ | Fibrinolytic URAK enzyme produced by Bacillus cereus NK1 | 1 mM, 24 hr without NaOH and 5 min with NaOH, 37˚C, URAK content: 1 mg, additives: 10 ml of Tris-Hcl buffer of pH 9 | UV-Vis TEM XRD AFM | Size―50 - 80 nm Shape―sph. Structure―FCC Nature―WD | AgNP with mmobilized enzyme |
97 | Kalishwarlal et al (2010) [ | Brevibacterium casei harvested cells | 1 mM, 24 hr, 37˚C, 1 g, Shaken, 30 min at 16000 g | UV-Vis TEM XRD FTIR FS | Size―10 - 50 nm. Shape―Sph. Structure―FCC | AgNP act as stable anti-coagulant |
98 | Ganeshbabu and Gunasekaran (2009) [ | Isolated and harvested Bacillus cereus PGN1 cells. | 1 mM, 120 hr, 37˚C. 10 g/100 ml. 15 min at 15000 rpm. Shaken. | UV-Vis FTIR XRD TEM | Size-4-5 nm Shape-Sph. Structure-FCC. Nature-MD. | Tris Buffer (pH-7) as suspension media for nanoparticles |
99 | Nanda et al (2009) [ | Staphylococcus aureus supernatant | 1 mM, 5 min | UV-Vis AFM | Size―160 - 180 nm Nature―PD. | AgNP antibacterial action against human pathogenic bacteria MRSA, MRSE, S. pyogenes |
100 | Kalimuthu et al (2008) [ | Bacillus icheniormis cells | 1 mM, 24 hr, 37˚C, 30 min at 15000 rpm. Shaken | UV-Vis SEM EDX XRD | Size―50 nm Structure―Crystal Nature―WD | |
Gram negative bacteria | ||||||
101 | Perni et al (2013) [ | Escherichia coli cells | 1 or 5 mM, 24 hr, 30˚C, Ratio of AgNO3: L-cysteine = 1:5, Shaken, 10 min at 1851 g | UV-Vis FTIR TEM TGA | Size―~5 nm | Capping agent: L-cysteine, Antimicrobial against E. coliand S. aureus |
102 | Juibari et al. (2011) [ | Ureibacillus thermo sphaerius supernatant | 1 - 100 mM, 24 hr, 60˚C - 80˚C, Dark, 15 min (13 k, rpm Static | UV-Vis DLS XRD FTIR TEM | Size―10 - 100 nm Shape―Sph. Structure―FCC Nature―PD | Temperature around 80˚C stands possible because of thermophilic nature of bacteria |
103 | Gurunathan et al. (2009) [ | E. coli supernatant | 1 - 10 mM, 24 hr, 20˚C - 90˚C, pH: 5 - 12, 10 min at 10k rpm Static | UV-Vis DLS TEM FTIR | Size―10 - 90 nm Shape―Sph. Structure―Crystal Nature―Uniform | Nitrate medium (pH-8) is used for culture. |
104 | Shahverdi et al (2007) [ | K. pneumonia (Enterobacteria) supernatant | 1 mM, 5 min, Room temp. | UV-Vis TEM EDS | Size―Avg: 52.25 nm Shape―Sph. | Nanoparticles are unstable after 5 min. Addition of piperitone resisted the nanoparticle growth. |
Bio-polymers |
105 | Cheng et al. (2014) [ | Chondrotin sulfate | 1 and 6.25 mM, 3 - 120 hr, 25˚C and 80˚C, 0.8 to 20 mg/l, 10 min at 5000 g, Stirred | UV-Vis FTIR TEM DLS | Size―<20 nm Shape―sph. | Stable for 2 months, Served as nano carrier for drug delivery |
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106 | Chen et al. (2014) [ | Chitosan biopolymer | UV-Vis FTIR TEM DLS | Size―~218.4 nm Shape―oval and sph. Nature―Ag/ chitosan nano hybrids | Antimicrobial to E. coli, S. choleraesuis, S. aureus and B. subtilis | |
107 | Tagad et al. (2013) [ | Locust bean gum polysaccharide. | 1 - 5 mM, 6 hr, 60˚C, 0.1 to 0.4 (w/v)/25 ml, pH: 4 to 12, Static | UV-Vis AFM | Size―18 - 51 nm | Stability: 7 months, AgNP served in development of H2O2 sensor |
108 | El-Rafie et al. (2013) [ | Crude hot water soluble polysaccharide extracted from different marine algae | 0.1 mM, 20 min, 70˚C, 0.3 (mg/ml)/1 ml, pH: 10.10 min at 5000 rpm, Stirring | UV-Vis FTIR TEM | Size―7 - 20 nm Shape―sph | Stability: 6 months, AgNP treated cotton fibers antibacterial to E. coli and S. aureus |
109 | Ashraf et al. (2013) [ | Casein milk protein | 1 mM, 5 - 10 min, 50˚C - 60˚C, 1-c10 ml/25 ml, pH: 10 - 14, vigorous stirring | UV-Vis FTIR SEM TEM DLS ZP | Size―pH > 7: 3 - 18 nm, pH < 6: 60 - 80 nm. Shape―sph. | Cytotoxocity and cellular uptake of AgNP was studied. |
110 | Dehnavi et al. (2013) [ | Fructose | 10 - 100 ppm, 11 - 100 min, 55˚C - 95˚C, 1(g/L)/9.35 ml, Other contents: Diammonium hydrogen citrate, 1 M ammonium solution, pH: 8.5 to 11.5, stirring | UV-Vis FE-SEM TEM XRD DLS | Size―36 nm Shape―sph. Structure― crystalline Nature―WD and homogenous | Stability for 1 month, Antibacterial to E. coli and S. aureus |
111 | Ortega-arroyo et al. (2013) [ | D-glucose | 0.13 to 0.97 M, 1 min, 26˚C - 94˚C, 150 µL (0.1 M)/100 µL, Capping agent-6ml of 1.7 wt%, pH: 7 to 13, Stirred | UV-Vis TEM XRD RS | Size―2 - 24 nm Shape―sph and polyhedral Structure―FCC Nature― homogenous WD | Smaller particle range of silver nanoparticles are observed at 0.55M D-glucose, pH-11 and temperature > 70˚C. |
112 | Lu et al. (2012) [ | Egg white extract | 10 mM, 72 hr, room temp. 1 ml/2 ml, Vigorous stirring, 15 min, 15k rpm | UV-Vis FTIR TEM DLS | Size―~20 nm Shape―sph Structure―Cryst | Silver nanoparticle conjugate is used in cancer radiation therapy. |
113 | Guidelli et al. (2012) [ | DL-Alanine | Ag/alanine ratio (%): 0.045 to 0.36, 40 min, 100˚C. vigorous stirring. | UV-Vis FTIR TEM XRD | Size-~7.5 nm Shape-sph. Structure-FCC | Nanoparticle stands applicable for ESR-Dosimetry. |
114 | Tanvir et al. (2012) [ | Co-enzyme (β-NADPH) | 0.31 - 10 mM, 20˚C. 1:1 to 3:1. Stirring, 30 min at 15000 rpm | UV-Vis TEM XRD DLS ZP EDAX | Size―20.77 ± 0.67 nm Shape―sph. Structure―FCC Nature―narrow and MD | Stabile for 2 months, The reagent used for the synthesis of nanoparticles can be regenerated. |
115 | Bankura et al. (2012) [ | Dextran | 0.01 M, room temp. 5%, Additive: 0.4 ml of 0.001 M NaOH, static | UV-Vis TEM XRD EDAX AFM | Size―5 - 60 nm Shape―sph. Structure―FCC Nature―WD | Stable for 1 months, Antimicrobial to B. subtilis, B. cereus, E. coli, S. aureus, P. aeruginosa |
116 | Sasikala et al. (2012) [ | Soyabean protein | 1 mM, 24 hr, room temp. 1 g/100 ml, 10 min at 10000 rpm, Static | UV-Vis FTIR HR-SEM HRTEM XRD EDAX | Size―7 - 29 nm Shape―sph. Structure―FCC Nature―WD | Protein of 51 kDa was responsible for the formation of AgNP formation. |
117 | Morales-Sanchez et al. [ | Albumin | 30 mM, 24 min, room temp. Additive: Ammonium hydroxide (pH: 11), Stirred | UV-Vis TEM TGA DLS | Size―~26 nm Shape―sph. | Stable for 6 months |
118 | El-rafie et al. (2011) [ | Hydropropyl starch | 100 - 750 ppm, 15 - 90 min, 30˚C - 90˚C, 9 g/l with 0.84 molar substitutions, pH: 2 - 12, Stirring | UV-Vis TEM | Size-6-8 nm | Stable for 6 months, More reduction at higher pH, rate increased rate with temp; particle aggregation with time |
119 | Philip (2010) [ | Honey | 1 mM, 1 min, 15 ml/20 ml, pH: 6.5 - 8.5, Stirred | UV-Vis FTIR HR-TEM XRD | Size―4 nm Shape―sph. Structure―FCC Nature―MD | Stabile for 6 months, NaOH is added for pH adjustment |
120 | Kora et al. (2010) [ | Gum kondagogu (Cochlospermum gossypium) | 1 - 5 mM, 10 - 60 min, 121˚C, 15 psi, 0.1 - 0.5(w/v), gum mean particle size: 30 - 300µm, Static | UV-Vis TEM XRD TGA | 1 mM AgNO3, (0.1) and (0.5) w/v% gum: Size―30 min―(55) and (11.2) nm; 60 min―(18.9) and (4.5) nm Shape―(R, hex) and (sph). Structure―FCC Nature―PD, WD | Anti-bacterial to S. aureus, E. coli, and P. aeruginosa |
Note: DLS―Dynamic light scattering, EDAX/EDS Energy Dispersive X-ray Analysis/Energy Dispersive Spectroscopy; FTIR―Fourier transform infrared spectroscopy, HRTEM―High Resolution Transmission Electron Microscopy; SEM―Scanning Electron Microscopy, TGA―Thermogra- vimetric analysis, UV-Vis―Ultra violet-visible spectroscopy; XRD―X Ray Diffraction, DEC―decahedral, sph―spherical, Tri―Triangular, R― Rod, Hex―Hexagonal, PD―Polydispersed, MD―monodispersed, WD―Well Dispersed, Cryst―Crystalline.
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The MIC is defined as the minimum concentration of the analyte which inhibit 100% visible growth of the targeted microbe after 24 hours. The MIC is determined by monitoring growth of bacteria in culture tubes inoculated with the same amount of bacterial culture but increasing concentration of AgNPs in the growth medium. The minimum concentration of AgNP which checks growth of bacteria is called the minimum inhibitory concentration. For the determination of MBC, fixed AgNP concentration greater than MIC value is added to the nutrient mediums containing increasing bacterial inoculum and bacterial growth is monitored, using UV-Vis spectroscopy or plate analyzer, for change in the optical density of the samples [
The SEM and TEM analyses have been used to monitor changes in the morphology of the bacterial cell before and after treatment with “AgNPs”; The visible alterations in the cell shape and perforations in the cell wall have been reported and used as indicator of the antimicrobial action of AgNPs by several workers [
The AgNPs have potent antibacterial action against gram positive bacteria, Lactobacillus fermentum [
The anti-bacterial action of AgNPs is quite complex and not well studied. Its mechanism is onlytentatively explained. The antimicrobial action of AgNPs can be categorized in two types: the inhibitory action and bactericidal action. In the former strategy bacterial cells are not killed but their division is prevented whereas in the later bacterial cells will die due to the action of AgNP [
and DNA damage. The above stated mechanism is in agreement with the reports of many authors [
The AgNPs exhibited antifungal action against various fungi [
The AgNPs have been found to be effective larvicidal agents against dengue vector Aedes aegypt [
The AgNPs synthesized from Rhizopus oryzae fungal species have been used for treating contaminated water and adsorption of pesticides [
There have been several reports on the use of AgNPs in the field of medicine. The AgNPs have been used as therapeutic agents [
Sufficient volume of published literature is available on the synthesis of AgNPs through green routes. Among plants, angiosperm species has been widely used in comparison with the other sources. Several characterizations methods and techniques have been used for AgNPs synthesis and confirmation. The AgNPs synthesized using biological reducing and capping agents have shown wide variation in shape and size. Among applications, the anti-microbial action of AgNPs has been widely studied. Various methods used to carry out antibacterial study and elucidate mechanism of anti-microbial have been developed. The results, however, are conflicting and there is a need for more work to resolve this issue. The potential of AgNPs for their use as drug carriers in cancer therapy, as biosensors for metabolites and pollutants, as catalyst etc. is quite high and requires intensive and integrated research activity for harnessing it.
One of the Authors (SNU) is grateful to the Department of Atomic Energy, GoI, Mumbai for the award of Raja Ramanna fellowship. The financial support to DDG in the form of Dr DS Kothari Postdoc fellowship from the UGC, New Delhi is gratefully acknowledged. Authors are also grateful to Head of the Department of Chemical Engineering and Technology, IIT (BHU) for providing necessary encouragement and facilities.
Sista KameswaraSrikar,Deen DayalGiri,Dan BahadurPal,Pradeep KumarMishra,Siddh NathUpadhyay, (2016) Green Synthesis of Silver Nanoparticles: A Review. Green and Sustainable Chemistry,06,34-56. doi: 10.4236/gsc.2016.61004