Size-controlled silver nanoparticles synthesized over the range 5–100 nm using the same protocol and their antibacterial efficacy

A systematic and detailed study for size-specific antibacterial efficacy of silver nanoparticles (AgNPs) synthesized using a co-reduction approach is presented here. Nucleation and growth kinetics during the synthesis process was precisely controlled and AgNPs of average size 5, 7, 10, 15, 20, 30, 50, 63, 85, and 100 nm were synthesized with good yield and monodispersity. We found the bacteriostatic/bactericidal effect of AgNPs to be size and dose-dependent as determined by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of silver nanoparticles against four bacterial strains. Out of the tested strains, Escherichia coli MTCC 443 and Staphylococcus aureus NCIM 5201 were found to be the most and least sensitive strains regardless of AgNP size. For AgNPs with less than 10 nm size, the antibacterial efficacy was significantly enhanced as revealed through delayed bacterial growth kinetics, corresponding MIC/MBC values and disk diffusion tests. AgNPs of the smallest size, i.e., 5 nm demonstrated the best results and mediated the fastest bactericidal activity against all the tested strains compared to AgNPs having 7 nm and 10 nm sizes at similar bacterial concentrations. TEM analysis of AgNP treated bacterial cells showed the presence of AgNPs on the cell membrane, and AgNPs internalized within the cells.

[1]  H. Luckarift,et al.  Hybrid antimicrobial enzyme and silver nanoparticle coatings for medical instruments. , 2009, ACS applied materials & interfaces.

[2]  M. Islam,et al.  Organic-soluble antimicrobial silver nanoparticle-polymer composites in gram scale by one-pot synthesis. , 2009, ACS applied materials & interfaces.

[3]  Cristina Rodríguez Padilla,et al.  Bactericidal effect of silver nanoparticles against multidrug-resistant bacteria , 2010 .

[4]  Chi-Ming Che,et al.  Proteomic analysis of the mode of antibacterial action of silver nanoparticles. , 2006, Journal of proteome research.

[5]  N. Monteiro-Riviere,et al.  Antibacterial efficacy of silver nanoparticles of different sizes, surface conditions and synthesis methods , 2011, Nanotoxicology.

[6]  L. Sabath,et al.  Clinical relevance of bacteriostatic versus bactericidal mechanisms of action in the treatment of Gram-positive bacterial infections. , 2004, Clinical infectious diseases : an official publication of the Infectious Diseases Society of America.

[7]  Rong Chen,et al.  Size-dependent antibacterial activities of silver nanoparticles against oral anaerobic pathogenic bacteria , 2013, Journal of Materials Science: Materials in Medicine.

[8]  Yen Wei,et al.  Facile synthesis of high-concentration, stable aqueous dispersions of uniform silver nanoparticles using aniline as a reductant. , 2011, Langmuir : the ACS journal of surfaces and colloids.

[9]  A Adin,et al.  Silver nanoparticle-E. coli colloidal interaction in water and effect on E. coli survival. , 2009, Journal of colloid and interface science.

[10]  Pedro J J Alvarez,et al.  Negligible particle-specific antibacterial activity of silver nanoparticles. , 2012, Nano letters.

[11]  Y. Qu,et al.  A simple approach towards uniform spherical Ag-like nanoparticles. , 2012, Nanoscale.

[12]  Sanjib Bhattacharyya,et al.  Intrinsic therapeutic applications of noble metal nanoparticles: past, present and future. , 2012, Chemical Society reviews.

[13]  Hong Yang,et al.  Direct Synthesis of Narrowly Dispersed Silver Nanoparticles Using a Single-Source Precursor , 2003 .

[14]  Stella M. Marinakos,et al.  Size-controlled dissolution of organic-coated silver nanoparticles. , 2012, Environmental science & technology.

[15]  Sefik Suzer,et al.  Synthesis, characterization and antibacterial investigation of silver-copper nanoalloys , 2011 .

[16]  R. Yadav,et al.  Ocimum sanctum mediated silver nano particles showed better antimicrobial activities compared to citrate stabilized silver nano particles against multidrug resistant bacteria , 2013 .

[17]  Daoben Zhu,et al.  Preparation of gold, platinum, palladium and silver nanoparticles by the reduction of their salts with a weak reductant–potassium bitartrate , 2003 .

[18]  M. Yacamán,et al.  The bactericidal effect of silver nanoparticles , 2005, Nanotechnology.

[19]  T. Xia,et al.  Toxic Potential of Materials at the Nanolevel , 2006, Science.

[20]  M. B. Cardoso,et al.  Size-selective silver nanoparticles: future of biomedical devices with enhanced bactericidal properties , 2011 .

[21]  Jun-Yan Zhang,et al.  Silver nanoparticles capped by oleylamine: formation, growth, and self-organization. , 2007, Langmuir : the ACS journal of surfaces and colloids.

[22]  Xiao-Hong Nancy Xu,et al.  Real-time probing of membrane transport in living microbial cells using single nanoparticle optics and living cell imaging. , 2004, Biochemistry.

[23]  Alexander Pyatenko,et al.  Synthesis of Spherical Silver Nanoparticles with Controllable Sizes in Aqueous Solutions , 2007 .

[24]  C. Murphy,et al.  Seedless, Surfactantless Wet Chemical Synthesis of Silver Nanowires , 2003 .

[25]  Younan Xia,et al.  Shape-Controlled Synthesis of Gold and Silver Nanoparticles , 2002, Science.

[26]  P. Tam,et al.  Silver nanoparticles: partial oxidation and antibacterial activities , 2007, JBIC Journal of Biological Inorganic Chemistry.

[27]  V. Sharma,et al.  Silver nanoparticles: green synthesis and their antimicrobial activities. , 2009, Advances in colloid and interface science.

[28]  Dae Hong Jeong,et al.  Antimicrobial effects of silver nanoparticles. , 2007, Nanomedicine : nanotechnology, biology, and medicine.

[29]  C. Ni,et al.  Antibacterial properties of silver-doped titania. , 2007, Small.

[30]  S. Agarwal,et al.  Delineating Bacteriostatic and Bactericidal Targets in Mycobacteria Using IPTG Inducible Antisense Expression , 2009, PloS one.

[31]  N. Ibrahim,et al.  Antibacterial activity of silver bionanocomposites synthesized by chemical reduction route , 2012, Chemistry Central Journal.

[32]  I. Sondi,et al.  Silver nanoparticles as antimicrobial agent: a case study on E. coli as a model for Gram-negative bacteria. , 2004, Journal of colloid and interface science.

[33]  J. Song,et al.  Does the Antibacterial Activity of Silver Nanoparticles Depend on the Shape of the Nanoparticle? A Study of the Gram-Negative Bacterium Escherichia coli , 2007, Applied and Environmental Microbiology.

[34]  Jun Li,et al.  Shape Control of Silver Nanoparticles by Stepwise Citrate Reduction , 2009 .

[35]  O. Stéphan,et al.  Electroless growth of silver nanoparticles into mesostructured silica block copolymer films. , 2010, Langmuir.

[36]  G. U. Kulkarni,et al.  Size-dependent chemistry: properties of nanocrystals. , 2002, Chemistry.

[37]  L. F. Gorup,et al.  International Journal of Antimicrobial Agents the Growing Importance of Materials That Prevent Microbial Adhesion: Antimicrobial Effect of Medical Devices Containing Silver , 2022 .

[38]  S. Mukherji,et al.  Antimicrobial chitosan–PVA hydrogel as a nanoreactor and immobilizing matrix for silver nanoparticles , 2012, Applied Nanoscience.

[39]  S. Mukherji,et al.  Immobilized silver nanoparticles enhance contact killing and show highest efficacy: elucidation of the mechanism of bactericidal action of silver. , 2013, Nanoscale.

[40]  M. Albrecht,et al.  Plasma resonance enhancement of Raman scattering by pyridine adsorbed on silver or gold sol particles of size comparable to the excitation wavelength , 1979 .

[41]  Facundo Ruiz,et al.  Synthesis and antibacterial activity of silver nanoparticles with different sizes , 2008 .

[42]  G. Lowry,et al.  Towards a definition of inorganic nanoparticles from an environmental, health and safety perspective. , 2009, Nature nanotechnology.

[43]  Schneider,et al.  Reproducible Preparation of Silver Sols with Small Particle Size Using Borohydride Reduction: For Use as Nuclei for Preparation of Larger Particles. , 1999, Journal of colloid and interface science.

[44]  Andreas Kornowski,et al.  Determination of nanocrystal sizes: a comparison of TEM, SAXS, and XRD studies of highly monodisperse CoPt3 particles. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[45]  I. Yu,et al.  Toxicity of various silver nanoparticles compared to silver ions in Daphnia magna , 2012, Journal of Nanobiotechnology.

[46]  Alexander Wokaun,et al.  Nanoparticles in energy technology: examples from electrochemistry and catalysis. , 2005, Angewandte Chemie.

[47]  Chuyang Y. Tang,et al.  Hollow fiber membrane decorated with Ag/MWNTs: toward effective water disinfection and biofouling control. , 2011, ACS nano.

[48]  Siddhartha P Duttagupta,et al.  Strain specificity in antimicrobial activity of silver and copper nanoparticles. , 2008, Acta biomaterialia.

[49]  S. Hsu,et al.  Antibacterial properties of silver nanoparticles in three different sizes and their nanocomposites with a new waterborne polyurethane , 2010, International journal of nanomedicine.

[50]  Sebastian Schlücker,et al.  Monodispersity and size control in the synthesis of 20-100 nm quasi-spherical silver nanoparticles by citrate and ascorbic acid reduction in glycerol-water mixtures. , 2012, Chemical communications.