Siddhartha Shrivastava

Characterization of enhanced antibacterial effects of novel silver nanoparticles

In the present study, we report the preparation of silver nanoparticles in the range of 10‐15 nm with increased stability and enhanced anti-bacterial potency. The morphology of the nanoparticles was characterized by transmission electron microscopy. The antibacterial effect of silver nanoparticles used in this study was found to be far more potent than that described in the earlier reports. This effect was dose dependent and was more pronounced against gram-negative bacteria than gram-positive organisms. Although bacterial cell lysis could be one of the reasons for the observed antibacterial property, nanoparticles also modulated the phosphotyrosine profile of putative bacterial peptides, which could thus affect bacterial signal transduction and inhibit the growth of the organisms.

Characterization of Antiplatelet Properties of Silver Nanoparticles

Thrombotic disorders have emerged as serious threat to society. As anticoagulant and thrombolytic therapies are usually associated with serious bleeding complications, the focus has now shifted to regulating and maintaining platelets in an inactive state. In the present study we show that nanosilver has an innate antiplatelet property and effectively prevents integrin-mediated platelet responses, both in vivo and in vitro, in a concentration-dependent manner. Ultrastructural studies show that nanosilver accumulates within platelet granules and reduces interplatelet proximity. Our findings further suggest that these nanoparticles do not confer any lytic effect on platelets and thus hold potential to be promoted as antiplatelet/antithrombotic agents after careful evaluation of toxic effects.

Thrombus inducing property of atomically thin graphene oxide sheets

Graphene oxide (GO), the new two-dimensional carbon nanomaterial, is extensively investigated for potential biomedical applications. Thus, it is pertinent to critically evaluate its untoward effects on physiology of tissue systems including blood platelets, the cells responsible for maintenance of hemostasis and thrombus formation. Here we report for the first time that atomically thin GO sheets elicited strong aggregatory response in platelets through activation of Src kinases and release of calcium from intracellular stores. Compounding this, intravenous administration of GO was found to induce extensive pulmonary thromboembolism in mice. Prothrombotic character of GO was dependent on surface charge distribution as reduced GO (RGO) was significantly less effective in aggregating platelets. Our findings raise a concern on putative biomedical applications of GO in the form of diagnostic and therapeutic tools where its prothrombotic property should be carefully investigated.

Applying Nanotechnology to Human Health: Revolution in Biomedical Sciences

Recent research on biosystems at the nanoscale has created one of the most dynamic science and technology domains at the confluence of physical sciences, molecular engineering, biology, biotechnology, and medicine. This domain includes better understanding of living and thinking systems, revolutionary biotechnology processes, synthesis of new drugs and their targeted delivery, regenerative medicine, neuromorphic engineering, and developing a sustainable environment. Nanobiosystems research is a priority in many countries and its relevance within nanotechnology is expected to increase in the future. The realisation that the nanoscale has certain properties needed to solve important medical challenges and cater to unmet medical needs is driving nanomedical research. The present review explores the significance of nanoscience and latest nanotechnologies for human health. Addressing the associated opportunities, the review also suggests how to manage far-reaching developments in these areas.

Label-free colorimetric estimation of proteins using nanoparticles of silver

Metallic nanoparticles have received considerable attention in bioassays and diagnostics due to their unique surface plasmon resonance (SPR) properties. Gold nanoparticles have been employed for the development of SPR-based colorimetric bioassays. In the present report we have described a sensitive colorimetric approach for estimation of proteins, within a detection limit of 10∼80 μg/mL, using unmodified silver nanoparticles. Besides the common advantages of colorimetric assay such as simplicity, high sensitivity, and low cost, our method has a label-free design and provides an important and attractive alternative to classical sensing probes and systems. The present work will contribute to the development of nanotechnology-based diagnostic tools.

Negative regulation of fibrin polymerization and clot formation by nanoparticles of silver

Thrombolytic therapy in acute stroke has reduced ischemia; however, it is also associated with increased incidence of intracerebral hemorrhage and expanding stroke. Platelets and fibrin are the major components of thrombi. Since fibrin is available in large concentration at lesion sites and in all types of thrombi, it is an obvious target for majority of antithrombotic therapies. Previously we have demonstrated innate antiplatelet properties with nanosilver. It can effectively prevent platelet activation in response to physiological agonists, under both in vitro as well as ex vivo conditions, and immobilize and stabilize proteins. Here we report for the first time that nanosilver can significantly retard fibrin polymerization kinetics both in pure and plasma-incorporated systems and hence can impede thrombus formation. We also discuss the conformational changes ensued upon fibrinogen following interaction with nanosilver. Together with its inherent antiplatelet and antibacterial properties, capacity to inhibit fibrin polymerization can open up possibilities of newer biomedical application and research potential involving silver nanoparticles.

INVITED PAPER: Agrifood Nanotechnology: A Tiny Revolution in Food and Agriculture

Nanotechnology focuses on special properties of a material which emerge from nanometer size—is becoming one of the most promising scientific fields of research in decades. The realisation that the nano-scale has certain properties needed to solve important biomedical challenges and cater to unmet biomedical needs is driving nano-biosystem research. Proper nutrition and a clean environment promote human health. Nanotechnologies are only used to a limited extent at the moment for achieving these aims although it has the potential to revolutionize agriculture and food systems. We will see increasing uses of tools and techniques developed by nanotechnology to detect carcinogenic pathogens and biosensors for improved and contamination free food and agricultural products. This article will review some of the current nanotechnology research that is applicable to agriculture and food technology and project what the future will bring to the newly emerging field of Agrifood Nanotechnology.

Nanotechnology in Food Sector and Agriculture

Proper nutrition and a clean environment promote human health. Nanotechnology is used to a limited extent at the moment for achieving these aims although it has the potential to revolutionize agriculture and food sectors by their ground breaking scientific innovations. So far, the use of nanotechnology in agriculture has been mostly theoretical, but it has begun and will continue to have a significant effect in the main areas of the food industry: development of new functional materials, product development, and design of methods and instrumentation for food safety and bio-security. The effects on society as a whole will be dramatic. The article reviews some of the current nanotechnology research that is applicable to agriculture and food technology and project what the future will bring to the newly emerging field of Agrifood Nanotechnology.

Metallic Nanoparticles: Biological Perspective

Among different nanomaterials employed for biomedical research, metallic nanoparticles (NPs) have been proved to be the most suitable. Based on their unique optical, physical, and electrical properties, metallic NPs have found significant applications in a wide spectrum of biomedical utilities like imaging, sensing, drug delivery, and gene targeting. Reports from our lab and others suggest that some of these NPs can also have significant therapeutic potential. Their application list is ever increasing in view of relatively lesser toxicity reported with these NPs. Attempts are also being made to synthesize highly stable and biocompatible NPs, which can be easily ingested or injected into the body. Realizing the potential role of metallic NPs in areas of biology and medicine, we have summarized here their characteristics and potential for biomedical applications. Addressing the associated opportunities we have also attempted to suggest how to manage far-reaching developments in these areas.