This color would be due to the excitations of surface plasmon resonance of silver with its characteristic absorbance at 439 nm. 10 and 11 It is noteworthy that the spectra belong to isotropic and spherical nanoparticles of size 35.42 nm which was further

confirmed by SEM. This investigation is in agreement with reports on the adsorption peak sites selleck compound and their basic relatedness to the particle size. 12 The reducing entities of A1 behaved as reducing and capping agent accounting for stability. The antimicrobial assessment showed a significant inhibitory effect against both positive and negative pathogens. Among the bacterial strains, Gram-negative K. pneumoniae and S. marcescens were found less susceptible toward the SNPs. This Hydroxychloroquine phenomenon might be associated to the structure of cells wherein the cell wall of negative bacteria were very much thinner ∼10–15 nm compared with positive bacteria ∼20–80 nm. 13 The second probable reason might be that K. pneumoniae is capsulated and forms mucoid colonies, which prevents the SNPs infiltration. Similarly, S. marcescens produces a non-diffusible pigment, prodigiosin that act as a defense mechanism in overcoming the environmental stress. The surface modified SNPs with positive

charge have greater affinity toward negatively charged bacterium on electrostatic interaction invoking an important determinant of the biocidal activity. 14 The antibacterial potential of SNPs ≤20 μg toward the pathogens tested is in agreement with the earlier report. 15 The SNPs in the size range from 10 to 80 nm could gain entry via membrane damage has been reported which is also observed in the present study. 16 The probable modus operandi involved include denaturation of proteins

upon binding to sulfhydryl groups or forming complex with electron donor groups normally present as thiols or phosphates on amino acids and nucleic acids. 17 The current investigation on the toxic potential of SNPs on bacterial genomic DNA showed complete fragmentation attributing to deletions, single and double strand breakage or adduct CYTH4 formation resulting in DNA damage after 12 h preceded by condensation and localization of DNA after 6 h. In general terms, toxicity can be included under apoptosis or necrosis where the cells abide by their own regulatory mechanism influenced by external stress. 18 As compared with the eukaryotic genome, the absence of DNA binding proteins in prokaryotes influenced the RO generation through the release of silver ions by SNPs. This follows the same trend in the toxicity induced in mitochondrial DNA. 19 Hence, it can be assumed that silver nanoparticles are broad-spectrum agents whose performance is not obstructed by antibiotic resistant mechanisms. This direct DNA damage may be influenced by SNPs and their continuous exposure might alter the genetic constitution of biological system.