Ajeet Singh

Characterization of silver nanoparticles synthesized using Urtica dioica Linn. leaves and their synergistic effects with antibiotics

Abstract In continuation of the efforts for synthesizing silver nanoparticles (AgNPs) by green chemistry route, here we report a facile bottom-up ‘green’ route for the synthesis of AgNPs using aqueous leaves extract of Urtica dioica (Linn.). The synthesized AgNPs were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), Zeta-sizer and Zeta-potential, Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) spectroscopy, Transmission electron microscopy (TEM) and Selected area electron diffraction (SAED). The results obtained from various characterizations revealed that AgNPs were in the size range of 20–30 nm and crystallized in face-centered-cubic structure. The antibacterial activity against Gram-positive (Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Salmonella typhimurium) bacterial pathogens was demonstrated by synthesized nanoparticles. Further, synergistic effects of AgNPs with various antibiotics were evaluated against above mentioned bacterial pathogens. The results showed that AgNPs in combination with antibiotics have better antibacterial effect as compared with AgNPs alone and hence can be used in the treatment of infectious diseases caused by bacteria. The maximum effect, with a 17.8 fold increase in inhibition zone, was observed for amoxicillin with AgNPs against S. marcescens proving the synergistic role of AgNPs. Therefore, it may be used to augment the activities of antibiotics.

Differentially expressed seed aging responsive heat shock protein OsHSP18.2 implicates in seed vigor, longevity and improves germination and seedling establishment under abiotic stress

Small heat shock proteins (sHSPs) are a diverse group of proteins and are highly abundant in plant species. Although majority of these sHSPs were shown to express specifically in seed, their potential function in seed physiology remains to be fully explored. Our proteomic analysis revealed that OsHSP18.2, a class II cytosolic HSP is an aging responsive protein as its abundance significantly increased after artificial aging in rice seeds. OsHSP18.2 transcript was found to markedly increase at the late maturation stage being highly abundant in dry seeds and sharply decreased after germination. Our biochemical study clearly demonstrated that OsHSP18.2 forms homooligomeric complex and is dodecameric in nature and functions as a molecular chaperone. OsHSP18.2 displayed chaperone activity as it was effective in preventing thermal inactivation of Citrate Synthase. Further, to analyze the function of this protein in seed physiology, seed specific Arabidopsis overexpression lines for OsHSP18.2 were generated. Our subsequent functional analysis clearly demonstrated that OsHSP18.2 has ability to improve seed vigor and longevity by reducing deleterious ROS accumulation in seeds. In addition, transformed Arabidopsis seeds also displayed better performance in germination and cotyledon emergence under adverse conditions. Collectively, our work demonstrates that OsHSP18.2 is an aging responsive protein which functions as a molecular chaperone and possibly protect and stabilize the cellular proteins from irreversible damage particularly during maturation drying, desiccation and aging in seeds by restricting ROS accumulation and thereby improves seed vigor, longevity and seedling establishment.

Green synthesis of nanostructured silver particles and their catalytic application in dye degradation

Today, discharge of hazardous dyes from textile industries in water bodies like lakes, rivers and groundwater has become a serious problem, which contributes to increase their pollution levels significantly. These pollutants are difficult to remove by traditional water treatment procedures. Thus, there is a need to develop more suitable methods of effluent treatment. Here, we describe use of green-synthesized nanostructured silver particles in degradation of hazardous dyes like Safranine O, Methyl red, Methyl orange and Methylene blue etc. The silver nanoparticles (AgNPs) used as nanocatalysts were synthesized using Zanthoxylum armatum leaves. The reduction of silver ions and the formation of AgNPs have been assessed by UV–Vis spectroscopy. DLS, SEM–EDX, TEM, SAED and XRD studies revealed that the AgNPs were crystalline in nature with size range from 15 to 50 nm. The report emphasizes that the AgNPs are observed to be an excellent catalyst on reduction of hazardous dyes, which is confirmed by a decrease in absorbance maximum values.

Biosynthesis, characterization and antibacterial activity of silver nanoparticles using an endophytic fungal supernatant of Raphanus sativus

Graphical abstract

Rice PROTEIN l-ISOASPARTYL METHYLTRANSFERASE isoforms differentially accumulate during seed maturation to restrict deleterious isoAsp and reactive oxygen species accumulation and are implicated in seed vigor and longevity.

PROTEIN l-ISOASPARTYL O-METHYLTRANSFERASE (PIMT) is a protein-repairing enzyme involved in seed vigor and longevity. However, the regulation of PIMT isoforms during seed development and the mechanism of PIMT-mediated improvement of seed vigor and longevity are largely unknown. In this study in rice (Oryza sativa), we demonstrate the dynamics and correlation of isoaspartyl (isoAsp)-repairing demands and PIMT activity, and their implications, during seed development, germination and aging, through biochemical, molecular and genetic studies. Molecular and biochemical analyses revealed that rice possesses various biochemically active and inactive PIMT isoforms. Transcript and western blot analyses clearly showed the seed development stage and tissue-specific accumulation of active isoforms. Immunolocalization studies revealed distinct isoform expression in embryo and aleurone layers. Further analyses of transgenic lines for each OsPIMT isoform revealed a clear role in the restriction of deleterious isoAsp and age-induced reactive oxygen species (ROS) accumulation to improve seed vigor and longevity. Collectively, our data suggest that a PIMT-mediated, protein repair mechanism is initiated during seed development in rice, with each isoform playing a distinct, yet coordinated, role. Our results also raise the intriguing possibility that PIMT repairs antioxidative enzymes and proteins which restrict ROS accumulation, lipid peroxidation, etc. in seed, particularly during aging, thus contributing to seed vigor and longevity.

Evaluation of antibacterial activity from phytosynthesized silver nanoparticles against medical devices infected with Staphylococcus spp.

Objectives Biofilm formation on the surface of medical devices, such as artificial prosthetics and catheters, are serious challenges to biomedical science. Most conventional methods, such as antibiotic therapy and medical device replacement, have failed because of low efficiency in medical environments. In the present study, we aimed to prevent infection by human pathogens Staphylococcus epidermidis (35984) and Staphylococcus aureus (740), which are resistant to antibiotic therapy. To prevent these infections, phytosynthesized silver nanoparticles (AgNPs) coating was tested. Methods The AgNPs were synthesized using aqueous extract of Berberis asiatica leaves and were characterized by UV–vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). The viable cells of bacteria were counted using a digital colony counter. Results AgNPs were 15 nm–35 nm in size and crystallized in a face-centred-cubic structure. Furthermore, the AgNPs coating on glass surfaces were bactericidal. Conclusions This study suggested that phytosynthesized AgNPs capped with various biomolecules present in leaf extracts of B. asiatica coated on glass surface prevent S. epidermidis and S. aureus associated infections of medical devices. Thus, coating of phytosynthesized AgNPs on glass surfaces may provide efficient antibacterial treatment of infected medical devices.

Understanding the role of Salmonella pathogenic island 1 (SPI-I) and host-pathogen interaction for typhoid using system biology approach

Salmonella, a Gram-negative bacterium species capable of causing a variety of food-and water-borne infections. Salmonella is reported as multiple drug resistant to various drugs which makes pharmaceutical industries work and develop new strategies for producing effective antibiotics against them. With the molecular advancement and better understanding of their pathway architecture, a channel for developing better antibiotics is open. Here, we tried to understand the enzyme kinetics of pathogenicity island in Salmonella and host-pathogen relationship by system biology approach. With taking consideration, we have identified in the pathogenic island, control over HilA is governed by HilC, HilD, RtsA combinatorial effect and concentration of each factor directly related during the time interval. It was observed that higher concentration of HilD, SipA, SipD in the diseased state leads to enhance the level of CDC42 and Arp2/3 complex protein expression during pathogen infect the cell. This study opens target for developing future drugs against Salmonella typhi infection.

Systems biology approach deciphering the biochemical signaling pathway and pharmacokinetic study of PI3K/mTOR/p53-Mdm2 module involved in neoplastic transformation

Cancer is a serious health concern growing at a rapid speed where normal cells take neoplastic transformation. Different pathway is tightly regulated with each other to maintain the harmony and sudden changes in single protein leads to aberrant changes in the whole system. Development of drugs to target these proteins aimed to block the signaling route that leads to cell death. Here, in this study, we performed in silico expression analysis of these potential proteins using system biological approach by mimicking the cell and understanding the behavior of different proteins in drugging condition. We performed in silico biomolecular interaction analysis for exploring the potential plant-derived compounds that can be served as an anticancerous drug with least toxicity by comparing with reference drug approved by FDA. Our results suggest that PI3K, p53-Mdm2 proteins are ideal proteins for targeting cancer cells, while overexpression of mTOR protein was observed when drug targeted this receptor. We state that PI3K family protein plays important role in drug discovery, and compounds obtained from in silico analysis can be served as a potential anticancerous drug for treating different cancer types.