Biplab Sarkar

An investigation on the antibacterial, cytotoxic, and antibiofilm efficacy of starch-stabilized silver nanoparticles.

The increased emergence of drug resistant microbes creates a major challenge to the scientific community for successful development of effective therapeutics. The antimicrobial activities of silver ions are well known, but limited information is available on the effects of green silver-nanoparticles (AgNPs) on human pathogens. In this article, we evaluated the antibacterial activity of starch-stabilized AgNPs against a panel of human pathogens commonly associated with air, water and food borne infections. The shape and size distribution of AgNPs were characterized by transmission electron microscopy. We showed that AgNPs were more effective against Gram-positive and Gram-negative pathogens as compared with acid-fast bacteria. AgNPs were not cytotoxic to macrophages at the bactericidal concentration and can augment intracellular killing potential of macrophages. Furthermore, we showed that AgNPs disrupt biofilm formation and exhibit better antibacterial activity compared to human cationic antimicrobial peptide LL-37. In summary, our data suggest AgNPs as a promising template for the design of novel antibacterial agents.

Microbial siderophores and their potential applications: a review

Siderophores are small organic molecules produced by microorganisms under iron-limiting conditions which enhance the uptake of iron to the microorganisms. In environment, the ferric form of iron is insoluble and inaccessible at physiological pH (7.35–7.40). Under this condition, microorganisms synthesize siderophores which have high affinity for ferric iron. These ferric iron-siderophore complexes are then transported to cytosol. In cytosol, the ferric iron gets reduced into ferrous iron and becomes accessible to microorganism. In recent times, siderophores have drawn much attention due to its potential roles in different fields. Siderophores have application in microbial ecology to enhance the growth of several unculturable microorganisms and can alter the microbial communities. In the field of agriculture, different types of siderophores promote the growth of several plant species and increase their yield by enhancing the Fe uptake to plants. Siderophores acts as a potential biocontrol agent against harmful phyto-pathogens and holds the ability to substitute hazardous pesticides. Heavy-metal-contaminated samples can be detoxified by applying siderophores, which explicate its role in bioremediation. Siderophores can detect the iron content in different environments, exhibiting its role as a biosensor. In the medical field, siderophore uses the “Trojan horse strategy” to form complexes with antibiotics and helps in the selective delivery of antibiotics to the antibiotic-resistant bacteria. Certain iron overload diseases for example sickle cell anemia can be treated with the help of siderophores. Other medical applications of siderophores include antimalarial activity, removal of transuranic elements from the body, and anticancer activity. The aim of this review is to discuss the important roles and applications of siderophores in different sectors including ecology, agriculture, bioremediation, biosensor, and medicine.

Silver-based nanoparticles induce apoptosis in human colon cancer cells mediated through p53

AIM The authors have systematically investigated the anticancer potentiality of silver-based nanoparticles (AgNPs) and the mechanism underlying their biological activity in human colon cancer cells. MATERIALS & METHODS Starch-capped AgNPs were synthesized, characterized and their biological activity evaluated through multiple biochemical assays. RESULTS AgNPs decreased the growth and viability of HCT116 colon cancer cells. AgNP exposure increased apoptosis, as demonstrated by an increase in 4´,6-diamidino-2-phenylindole-stained apoptotic nuclei, BAX/BCL-XL ratio, cleaved poly(ADP-ribose) polymerase, p53, p21 and caspases 3, 8 and 9, and by a decrease in the levels of AKT and NF-κB. The cell population in the G1 phase decreased, and the S-phase population increased after AgNP treatment. AgNPs caused DNA damage and reduced the interaction between p53 and NF-κB. Interestingly, no significant alteration was noted in the levels of p21, BAX/BCL-XL and NF-κB after AgNP treatment in a p53-knockout HCT116 cell line. CONCLUSION AgNPs are bona fide anticancer agents that act in a p53-dependent manner. Original submitted 16 March 2012; Revised submitted 25 August 2012; Published online 21 March 2013.

Selenium Nanoparticles for Stress-Resilient Fish and Livestock

The fisheries and livestock sectors capture the highest share of protein-rich animal food and demonstrate accelerated growth as an agriculture subsidiary. Environmental pollution, climate change, as well as pathogenic invasions exert increasing stress impacts that lead the productivity momentum at a crossroads. Oxidative stress is the most common form of stress phenomenon responsible for the retardation of productivity in fisheries and livestock. Essential micronutrients play a determinant role in combating oxidative stress. Selenium, one of the essential micronutrients, appears as a potent antioxidant with reduced toxicity in its nanoscale form. In the present review, different methods of synthesis and characterization of nanoscale selenium have been discussed. The functional characterization of nano-selenium in terms of its effect on growth patterns, feed digestibility, and reproductive system has been discussed to elucidate the mechanism of action. Moreover, its anti-carcinogenic and antioxidant potentiality, antimicrobial and immunomodulatory efficacy, and fatty acid reduction in liver have been deciphered as the new phenomena of nano-selenium application. Biologically synthesized nano-selenium raises hope for pharmacologically enriched, naturally stable nanoscale selenium with high ecological viability. Hence, nano-selenium can be administered with commercial feeds for improvising stress resilience and productivity of fish and livestock.

Seasonal changes in hematological parameters of Catla catla (Hamilton 1822)

Hematological parameters are repeatedly used as an essential diagnostic tool to assess the health condition of fish. The purpose of this study was to assess the reference values of some hematological parameters of Catla, Catla catla collected from a freshwater pond in a tropical climate of India from July 2008 to June 2010. Variations in hematological parameters such as hemoglobin, erythrocyte count, total leucocyte count, hematocrit, mean corpuscular volume (MCV), and mean corpuscular hemoglobin concentration (MCHC) of fish were compared according to sex and seasonal differences. Analysis of variance showed that there were significant differences between sexes and the results indicated that blood parameters levels between the sexes in summer were significantly different than that measure in other seasons except mean corpuscular hemoglobin (MCH) and MCHC value (P < 0.05). The number of total leukocyte levels was found to be higher in female fish especially in reproductive seasons, but the levels of hemoglobin, hematocrit, and MCV values were high in male fish in an annual period. However, there was no difference in MCH and MCHC values between the sexes and seasons throughout the study period. These may be related to season of sampling and changing physiological cycles during these months. The correlations between measured hematological parameters were also determined.

Optimization of the sublethal dose of silver nanoparticle through evaluating its effect on intestinal physiology of Nile tilapia (Oreochromis niloticus L.).

Silver nanoparticles (SNPs) are widely used in a variety of biomedical and consumer products as an antimicrobial additive. The present study was conducted to evaluate the impacts of low-dose SNPs on intestinal physiology of tilapia (Oreochromis niloticus L.) for assessing its apparent environmental risk due to extensive commercial use. SNPs were synthesized by a chemical reduction method yielding 1–27 nm oval shaped particles. Early fingerlings of tilapia were exposed with two sublethal concentrations (0.8 and 0.4 mg L−1) of SNPs for twenty one days period and its impact on the intestinal physiology was evaluated by histochemistry, catalase expression, glutamate dehydrogenase activity, SDS-PAGE and gut micro flora count. Histological analysis showed thinning of intestinal wall, swelling on mucosal layer and immunohistochemical assay exhibited an enhanced catalase expression in SNPs treated fishes. Gut microflora count elicited a dose-dependent depletion and a variable SDS-PAGE profile followed by significant (P < 0.05) elevations in glutamate dehydrogenase activity in SNPs-treated fishes. This study was designed to provide a better understanding of environmentally acceptable, dose-dependent SNPs delivery in fishes and to formulate guidelines in aquatic toxicology.

Formulation and Application of Biodegradable Nanoparticles Based Biopharmaceutical Delivery - An Efficient Delivery System

Biodegradable polymer based drug delivery has emerged as a promising and successful clinical tool for specific targeting and controlled drug release delivery system. Various other unique advantages associated with this delivery system include prolonged circulation, biocompatibility, degradation in nontoxic by-products etc. Till date, various biopharmaceutical agents have been successfully encapsulated within biodegradable polymers and used in clinics. However, before the clinical implementation of such nanocarriers different parameters have to be considered which influence the success of these nanocarriers such as drug release profile, size of nanocarrier, degradation mechanism, toxicity profile, type of polymer used, appropriate synthesis method, selection of mode of delivery etc. The following review focuses on such considerations to explore the area of designing and development of biodegradable polymeric nanosystems which when encapsulated with biopharmaceutical agents can be efficient for clinical application.

Application of Some Herbal Extracts and Calcium as an Antidote to Counteract the Toxic Effects of Cypermethrin and Carbofuran in Indian Major Carp, Labeo Rohita

Pesticides that are transported to the aquatic environment are primarily of agricultural origin. Sometimes, pesticides are applied to the fish ponds to control fish diseases. In the process, the residues that reach the hydrosphere are concentrated in certain parts of the aquatic ecosystem or remain in solution for extended periods or adsorbed to the particulate matter and thereby deposited in the sediments. Thus, pesticides could be accumulated in the body of the aquatic animals. Most of the pesticides act on the respiratory process and cholinergic nervous system and hamper the cell metabolism in addition to other disturbances. Thus, a formulation of antidotes to counteract pesticides is an important aspect of pollution research and work in this direction is in the initial stages. Zamfir (1979) worked on the possibilities of removal of pesticide polluted water in treatment stations and described some methodologies, i.e., flocculation and filtration that can partially removed DOT, 2,4,5-T, Endrin, Parathion and Lindane. Chlorine oxidation can remove parathion; diuron etc., ozone and potassium permanganate appear to extract effects similar to those of chlorination. Activated charcoal has positive effects in the removal of absorption of most pesticides and U-V rays also can remove a certain amount of pesticides. Some indirect approaches have also been employed by some scientists and their methods were environmental or nutritional manipulation. Sado et. al. (1992) reported that increased temperature and optimum levels of dissolved oxygen (by aerator) can decrease the pesticidal action. The application of lime to increase the pH for counteraction of the toxic effects of pesticides is also documented. Ghazaly (1994) and Mukherjee (1996) evaluated efficacy of ascorbic acid (vitamin C) for the intoxication of different pollutants including pesticides. Application of different herbal extracts for this purpose could play a very important role to mitigate the toxic effect of pesticides.