Sureshbabu Ram Kumar Pandian

Silver nanoparticles impede the biofilm formation by Pseudomonas aeruginosa and Staphylococcus epidermidis.

Biofilms are ensued due to bacteria that attach to surfaces and aggregate in a hydrated polymeric matrix. Formation of these sessile communities and their inherent resistance to anti-microbial agents are the source of many relentless and chronic bacterial infections. Such biofilms are responsible play a major role in development of ocular related infectious diseases in human namely microbial keratitis. Different approaches have been used for preventing biofilm related infections in health care settings. Many of these methods have their own demerits that include chemical based complications; emergent antibiotic resistant strains, etc. silver nanoparticles are renowned for their influential anti-microbial activity. Hence the present study over the biologically synthesized silver nanoparticles, exhibited a potential anti-biofilm activity that was tested in vitro on biofilms formed by Pseudomonas aeruginosa and Staphylococcus epidermidis during 24-h treatment. Treating these organisms with silver nanoparticles resulted in more than 95% inhibition in biofilm formation. The inhibition was known to be invariable of the species tested. As a result this study demonstrates the futuristic application of silver nanoparticles in treating microbial keratitis based on its potential anti-biofilm activity.

Biosynthesis of silver and gold nanoparticles using Brevibacterium casei

The present study demonstrates an unprecedented green process for the production of spherical-shaped Au and Ag nanoparticles synthesized and stabilized using a bacterium, Brevibacterium casei. Aqueous solutions of chloroaurate ions for Au and Ag(+) ions for silver were treated with B. casei biomass for the formation of Au nanoparticles (AuNP) and Ag nanoparticles (AgNP). The nanometallic dispersions were characterized by surface plasmon absorbance measuring at 420 and 540 nm for Ag and Au nanoparticles, respectively. Transmission electron microscopy showed the formation of nanoparticles in the range of 10-50 nm (silver), and 10-50 nm (gold). XRD analysis of the silver and gold nanoparticles confirmed the formation of metallic silver and gold. Further analysis carried out by Fourier Transform Infrared Spectroscopy (FTIR), provides evidence for the presence of proteins as possible biomolecules responsible for the reduction and capping agent which helps in increasing the stability of the synthesized silver and gold nanoparticles. The biological activities of the synthesized particles were confirmed based on their stable anti-coagulant effects. The use of bacterium for nanoparticles synthesis offers the benefits of ecofriendliness and amenability for large-scale production.

Anti-oxidant effect of gold nanoparticles restrains hyperglycemic conditions in diabetic mice

BackgroundOxidative stress is imperative for its morbidity towards diabetic complications, where abnormal metabolic milieu as a result of hyperglycemia, leads to the onset of several complications. A biological antioxidant capable of inhibiting oxidative stress mediated diabetic progressions; during hyperglycemia is still the need of the era. The current study was performed to study the effect of biologically synthesized gold nanoparticles (AuNPs) to control the hyperglycemic conditions in streptozotocin induced diabetic mice.ResultsThe profound control of AuNPs over the anti oxidant enzymes such as GSH, SOD, Catalase and GPx in diabetic mice to normal, by inhibition of lipid peroxidation and ROS generation during hyperglycemia evidence their anti-oxidant effect during hyperglycemia. The AuNPs exhibited an insistent control over the blood glucose level, lipids and serum biochemical profiles in diabetic mice near to the control mice provokes their effective role in controlling and increasing the organ functions for better utilization of blood glucose. Histopathological and hematological studies revealed the non-toxic and protective effect of the gold nanoparticles over the vital organs when administered at dosage of 2.5 mg/kilogram.body.weight/day. ICP-MS analysis revealed the biodistribution of gold nanoparticles in the vital organs showing accumulation of AuNPs in the spleen comparatively greater than other organs.ConclusionThe results obtained disclose the effectual role of AuNPs as an anti-oxidative agent, by inhibiting the formation of ROS, scavenging free radicals; thus increasing the anti-oxidant defense enzymes and creating a sustained control over hyperglycemic conditions which consequently evoke the potential of AuNPs as an economic therapeutic remedy in diabetic treatments and its complications.

Silver nanoparticles inhibit VEGF induced cell proliferation and migration in bovine retinal endothelial cells.

Angiogenesis, the growth of new blood vessels from pre-existing vasculature is of physiological and pathological importance. We have investigated the anti-angiogenic potential of silver nanoparticles, produced by Bacillus licheniformis. Bovine retinal endothelial cells (BRECs) were treated with the different concentrations of silver nanoparticles for 24 h in the presence and absence of vascular endothelial growth factor (VEGF), where 500 nM (IC50) of silver nanoparticle concentration, was able to block the proliferation and migration of BRECs. The cells showed a clear enhancement in caspase-3 activity and formation of DNA ladders, evidence of induction of apoptosis. Here we report for the first time that silver nanoparticles inhibit cell survival via PI3K/Akt dependent pathway in Bovine retinal endothelial cells.

Biological synthesis of gold nanocubes from Bacillus licheniformis

Microorganisms play an important role in the eco-friendly synthesis of metal nanoparticles. This study illustrates the synthesis of gold nanocubes using the bacterium Bacillus licheniformis after 48 h of incubation at room temperature. The morphology of the samples was analyzed using scanning electron microscopy (SEM) and the particles formed were characterized to be nanocubes. The size of gold nanocubes in aqueous solution has been calculated using UV-Vis spectroscopy, XRD and SEM measurements. The nanoparticles are found to be polydisperse nanocubes in the size range 10-100 nm.

ENHANCED SILVER NANOPARTICLE SYNTHESIS BY OPTIMIZATION OF NITRATE REDUCTASE ACTIVITY

Nanostructure materials are attracting a great deal of attention because of their potential for achieving specific processes and selectivity, especially in biological and pharmaceutical applications. The generation of silver nanoparticles using optimized nitrate reductase for the reduction of Ag(+) with the retention of enzymatic activity in the complex is being reported. This report involves the optimization of enzyme activity to bring about enhanced nanoparticle synthesis. Response surface methodology and central composite rotary design (CCRD) were employed to optimize a fermentation medium for the production of nitrate reductase by Bacillus licheniformis at pH 8. The four variables involved in the study of nitrate reductase were Glucose, Peptone, Yeast extract and KNO(3). Glucose had a significant effect on nitrate reductase production. The optimized medium containing (%) Glucose: 1.5, Peptone: 1, Yeast extract: 0.35 and KNO(3): 0.35 resulted in a nitrate reductase activity of 452.206 U/ml which is same as that of the central level. The medium A (showing least nitrate reductase activity) and the medium B (showing maximum nitrate reductase activity) were compared for the synthesis. Spectrophotometric analysis revealed that the particles exhibited a peak at 431 nm and the A(431) for the medium B was 2-fold greater than that of the medium A. The particles were also characterized using TEM. The particles synthesized using the optimized enzyme activity ranged from 10 to 80 nm and therefore can be extended to various medicinal applications.

Silver nano — A trove for retinal therapies

Pathological retinal angiogenesis (neovascularization) is one of the most feared complications among retinal diseases, leading to visual impairment and irreversible blindness. Recent findings made by us on therapeutic applications of biologically synthesized silver nanoparticles (AgNPs) against VEGF induced retinal endothelial cells, elucidates the effectual inhibitory activities of AgNPs over the downstream signaling pathways (Src and AKT/PI3K) leading to retinal angiogenesis. The current review focuses on the imperative role of VEGF induced angiogenesis in the development of retinal neovascularization and despite the fact that several VEGF targeting ocular drugs are available; the review examines the need for a cost economic alternative, thereby suggesting the role of AgNPs as an emerging economic ocular drug for retinal therapies. The current technologies available for the development of targeted and controlled release of drugs is being discussed and a model has been proposed for the amenable targeting mechanism, by which Poly gamma glutamic acid (PGA) capsulated AgNPs conjugated to cyclic RGD peptides carry out a sustained controlled release specifically targeting the neovascularization cells and induce apoptosis unaffecting the normal retinal cells. These constructs consequently affirm the futuristic application of silver nanoparticles as a boon to ocular therapies.

Optimization of α-amylase production for the green synthesis of gold nanoparticles

Biocompatible gold nanoparticles have received considerable attention in recent years because of their promising applications in bioimaging, biosensors, biolabels, and biomedicine. The generation of gold nanoparticles using extra-cellular alpha-amylase for the reduction of AuCl(4) with the retention of enzymatic activity in the complex is being reported. The enhanced synthesis of particles has been brought about by optimizing the medium components for alpha-amylase. Response surface methodology and central composite rotary design (CCRD) were employed to optimize a fermentation medium for the production of alpha-amylase by Bacillus licheniformis at pH 8. The three variables involved in the study of alpha-amylase were fructose, peptone and soya meal. Only fructose had a significant effect on alpha-amylase production. The most optimum medium (medB) containing (%) fructose: 3, peptone: 1, soya meal: 2, resulted in a amylase activity of 201.381 U/ml which is same as that of the central level. The least optimum (medA) and most optimum (medB) media were compared for the synthesis of particles indicated by difference in color formation. Spectrophotometric analysis revealed that the particles exhibited a peak at 582 nm and the A(582) for the Med B was 8-fold greater than that of the Med A. The TEM analysis revealed that the particle size ranged from 10 to 50 nm.

Synthesis of PHB nanoparticles from optimized medium utilizing dairy industrial waste using Brevibacterium casei SRKP2: A green chemistry approach

Polyhydroxyalkanoates (PHAs) are natural, biodegradable polymers accumulated by bacteria under nutritional exhausted condition where carbon source is in excess. A gram positive bacterium (designated strain SRKP2) that potentially accumulated polyhydroxybutyrate (PHB) was isolated from dairy industrial waste. From its morphological and physiological properties and nucleotide sequence of its 16S rRNA, it was suggested that strain SRKP2 was similar to Brevibacterium casei. PHAs were synthesized from a medium containing dairy waste, yeast extract and sea water. The synthesized PHAs were characterized by FT-IR as Polyhydroxybutyrate (PHB). Response surface methodology was applied to optimize the production of PHB. From the optimized medium the yield of PHB was found to be 2.940 g/L. Here we report the direct use of dairy waste and sea water as potential sources for the production of PHB. Produced PHB was used to synthesize nanoparticles using solvent displacement technique.

Mechanism of bactericidal activity of Silver Nitrate - a concentration dependent bi-functional molecule

Silver nitrate imparts different functions on bacteria depending upon its concentration. At lower concentration it induced synthesis of nanoparticles, whereas at higher concentrations it induced cell death. Bacillus licheniformis was used as model system. The MIC was 5 mM, and it induced catalase production, apoptotic body formation and DNA fragmentation.