Debabrata Dash

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.

Amine-Modified Graphene: Thrombo-Protective Safer Alternative to Graphene Oxide for Biomedical Applications

Graphene and its derivatives have attracted significant research interest based on their application potential in different fields including biomedicine. However, recent reports from our laboratory and elsewhere have pointed to serious toxic effects of this nanomaterial on cells and organisms. Graphene oxide (GO) was found to be highly thrombogenic in mouse and evoked strong aggregatory response in human platelets. As platelets play a central role in hemostasis and thrombus formation, thrombotoxicity of GO potentially limits its biomedical applications. Surface chemistry of nanomaterials is a critical determinant of biocompatibility, and thus differentially functionalized nanomaterials exhibit varied cellular toxicity. Amine-modified carbon nanotubes have recently been shown to possess cytoprotective action, which was not exhibited by their relatively toxic carboxylated counterparts. We, therefore, evaluated the effect of amine modification of graphene on platelet reactivity. Remarkably, our results revealed for the first time that amine-modified graphene (G-NH(2)) had absolutely no stimulatory effect on human platelets nor did it induce pulmonary thromboembolism in mice following intravenous administration. Further, it did not evoke lysis of erythrocytes, another major cellular component in blood. These findings contrasted strikingly the observations with GO and reduced GO (RGO). We conclude that G-NH(2) is not endowed with thrombotoxic property unlike other commonly investigated graphene derivatives and is thus potentially safe for in vivo biomedical applications.

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.

Fetal Growth in Maternal Anaemia

The effect of maternal iron deficiency anemia on fetal growth was studied in 54 anaemic (haemoglobin < 11.0 g/dl) mothers. Twenty-two mothers served as controls (haemoglobin > or = 11.0 g/dl). All the women had singleton live births at term gestation. The maternal iron status was assessed by serum ferritin estimation. The birth weight, head circumference, chest circumference, mid-arm circumference, and crown heel length were significantly low in infants born to women with moderate (haemoglobin 6.1 +/- 8.5 g/dl) and severe anaemia (haemoglobin < or = 6.0 g/dl), in comparison to infants born to non-anaemic women. Similarly, birth weight, mid-arm circumference, and crown-heel length were significantly low in infants of women with depleted iron stores (serum ferritin < 10 micrograms/l) than in infants of women with serum ferritin levels of 20 micrograms/l or more. All indices of fetal growth showed linear relationships with maternal haemoglobin, as well as with serum ferritin. The growth retarding effect of maternal anaemia was more on fetal birth weight and mid-arm circumference than on other anthropometric indices of the newborn.

Fetal iron status in maternal anemia

Hemoglobin, serum iron, transferrin saturation and ferritin were measured on paired maternal and cord blood samples in 54 anemic (hemoglobin < 110 g/L) and 22 non‐anemic (hemoglobin ≥ 110 g/L) pregnant women at term gestation. The levels of hemoglobin, serum iron, transferrin saturation and ferritin were significantly low in the cord blood of anemic women, suggesting that iron supply to the fetus was reduced in maternal anemia. The linear relationships of these parameters with both maternal hemoglobin and maternal serum ferritin indicated that the fetus extracted iron in amounts proportional to the levels available in the mother. Infants of mothers with moderate and severe anemia had significantly lower cord serum ferritin levels and hence poor iron stores at birth. It is concluded that iron deficiency anemia during pregnancy adversely affects the iron endowment of the infant at birth.

Cord Blood and Breast Milk Iron Status in Maternal Anemia

OBJECTIVES. The purpose of this work was to assess the effect of severe maternal iron-deficiency anemia and nutritional status on cord blood and breast milk iron status. METHODS. We conducted a prospective observational study over a 6-month period in a teaching hospital in central India. The study population consisted of 55 anemic (hemoglobin: <110 g/L) and 20 healthy nonanemic (hemoglobin: ≥110 g/L) pregnant women who delivered singleton live births at term gestation. We measured hemoglobin, iron, and ferritin levels in paired maternal and cord blood and iron levels in early (day 3 ± 1) and late (day 15 ± 3) transitional milk. Maternal anthropometry, including weight, height, midarm circumference, triceps skinfold thickness, and placental weight, were recorded. The main outcome measure of the study was to find out the relationship of maternal hemoglobin, iron, ferritin, and anthropometry with hemoglobin, iron, and ferritin in cord blood and iron levels in breast milk. RESULTS. Concentrations of hemoglobin, iron, and ferritin were significantly lower in the cord blood of anemic mothers and showed linear relationships with maternal hemoglobin and ferritin levels. Breast milk iron content was significantly reduced in severely anemic mothers but not in those with mild-to-moderate anemia. Breast milk iron level correlated with maternal hemoglobin and iron levels but not with ferritin levels. Maternal anthropometry had significant correlations with indices of iron nutriture in maternal and cord blood but showed no relationship with breast milk iron content. Placental weight was comparable between anemic and nonanemic mothers. CONCLUSIONS. Maternal anemia, particularly the severe type, adversely affects cord blood and breast milk iron status. Maternal nutritional status exerts a significant influence on fetal iron status but has little influence on breast milk iron content.

Attachment of biomolecules (protein and DNA) to amino-functionalized carbon nanotubes

An efficient method for the attachment of biomolecules [e.g. bovine serum albumin (BSA) protein and deoxyribonucleic acid (DNA)] to amino-group-functionalized multiwalled carbon nanotubes (f-MWCNTs) was reported. MWCNTs were prepared by spray pyrolysis of a benzene-ferrocene solution in argon atmosphere at ∼850 °C followed by functionalization with an amino group by chemical modification of carboxylic groups introduced on the nanotube surface. This process involves a direct coupling of ethylenediamine with carboxylic groups to introduce amino groups by amide formation. The as-synthesized MWCNTs, f-MWCNTs, and amino f-MWCNTs with BSA protein and DNA were characterized by scanning and transmission electron microscopy, and Fourier transform infrared spectroscopy, which confirm the attachment of biomolecules (BSA protein and DNA) to the amino f-MWCNTs.

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.