Stress Induced Lipids Accumulation in Naviculoid Marine Diatoms for Bioenergy Application

Microalgae are expected to play promising role in the production of biofuel in current research. Two of marine diatoms, Navicula sp. and Amphora sp. were isolated and their growth rate was also studied. Total lipid content was analyzed in stationary growth state under normal conditions. By the two stage process, both the diatoms were subjected to nitrogen and silicon undersupplied for five days and the total lipid accumulation in the diatoms were found to be increased during nutrient deficiency period. The nutrient deficit conditions prone to increased total lipid content and also altered the fatty acid profile in diatom. The total lipid content of Navicula sp. and Amphora sp. were found to be 34.93% DCW and 41.10% DCW under normal conditions and in nitrogen deficiency conditions it has been increased to 60.71% DCW and 64.72% DCW respectively. The major fatty acids were found to be cis-10-Heptadecanoic acid (27.54%) and stearic acid (24.57%). The level of saturated and monounsaturated fatty acids were found to be high in both the diatoms. The presence of low level of polyunsaturated fatty acids indicated that these two organisms could find future application in bioenergy production

Facile and Novel Strategy for Methods of Extraction of Biofuel Grade Lipids from Microalgae- an Experimental Report

The structural features of microalgal cell make it too difficult to extract the total lipid content of the cell as such. Thus, the cell disruption before lipid extraction becomes mandatory and has to be cost-effective. In the present study various methods and combination of few methods were adopted for effective extraction in order to choose the most effective cell disruption method for the complete extraction of lipids from a selected indigenous freshwater isolate, Scenedesmus sp. NTEB03. Interestingly, we found that grinding and bead-beating method showed two fold increased lipid productivity (23.2%) than the other methods tested. Biomass and lipid productivity of Scenedesmus sp., was found to be 0.0418 g L-1 d-1 and 4.3 mg L-1 d-1 respectively. Fatty acid profiles revealed that oleic (C18:1) and linoleic acid (C18:2) content being higher in the lipids, which are most appropriate for the biodiesel production. A novel strategy for most effective, simple method for cell disruption in Scenedesmus sp., was grinding/bead-beating, which is the most suitable method for complete extraction of biofuel grade lipids

An inhibitory action of chitosan nanoparticles against pathogenic bacteria and fungi and their potential applications as biocompatible antioxidants

Chitosan is the second most abundant polymer obtained from the byproduct of seafood. Chitosan and its derivatives and chitosan loaded drugs are the recent area of interest against microbial pathogenesis. The cationic chitosan nanoparticles (ChNPs) interact with the anionic surfaces of the microbial cell membrane, which promotes antimicrobial activity. Although, ChNPs are potential against pathogenic microbes, selection of adaptable, suitable and cost effective synthesis method is much important. In the present study, ChNPs were synthesized adopting ionic gelation using sodium tripolyphosphate as a cross linking agent and characterized by FTIR, DLS, SEM and TEM analysis. ChNPs were investigated for antimicrobial activity against bacterial (Escherichia coli and Staphylococcus aureus) and fungal (Candida albicans) pathogens. ChNPs showed bactericidal activity at the lower minimum inhibitory concentration of about 40–80 μg mL−1. Interestingly, ChNPs exhibits biocompatible antioxidant property by inhibiting DPPH free radicals at 76% and also proven to be a potential candidate against the microbial pathogenesis with an inevitable applications in biomedicine

Synthesis of Ag-Doped Tetrahedral Amorphous Carbon Coatings and Their Antibiofilm Efficacy for Medical Implant Application

Tetrahedral amorphous carbon (taC) is a hydrogen-free carbon with extensive properties such as hardness, optical transparency, and chemical inertness. taC coatings have attracted much attention in recent times, as have coatings doped with a noble metal. A known antimicrobial metal agent, silver (Ag), has been used as a dopant in taC, with different Ag concentrations on the Ti64 coupons using a hybrid filtered cathodic vacuum arc (FCVA) and magnetron sputtering system. The physiochemical properties of the coated surface were investigated using spectroscopic and electron microscopy techniques. A doping effect of Ag-taC on biofilm formation was investigated and found to have a significant effect on the bacterial-biofilm-forming bacteria Staphylococcus aureus and Pseudomonas aeruginosa depending on the concentration of Ag. Further, the effect of coated and uncoated Ag-taC films on a pathogenic bacterium was examined using SEM. The result revealed that the Ag-taC coatings inhibited the biofilm formation of S. aureus. Therefore, this study demonstrated the possible use of Ag-taC coatings against biofilm-related complications on medical devices and infections from pathogenic bacteria

Unveiling the Anti-Biofilm Property of Hydroxyapatite on <i>Pseudomonas aeruginosa</i>: Synthesis and Strategy

Biofilm-related nosocomial infections may cause a wide range of life-threatening infections. In this regard, Pseudomonas aeruginosa biofilm is becoming a serious health burden due to its capability to develop resistance to natural and synthetic drugs. The utilization of nanoparticles that inhibit biofilm formation is one of the major strategies to control infections caused by biofilm-forming pathogens. Hydroxyapatite (HA) is a synthetic ceramic material having properties similar to natural bones. Herein, a co-precipitation method followed by microwave treatment was used to synthesize HA nanoparticles (HANPs). The resulting HANPs were characterized using X-ray diffraction and transmission electron microscopy. Then, their antibiofilm properties against P. aeruginosa ATCC 10145 were examined in vitro. The needle-shaped HANPs were 30 and 90 nm long in width and length, respectively. The synthesized HANPs inhibited the biofilm formation of P. aeruginosa ATCC 10145 in a concentration-dependent manner, which was validated by light and confocal laser scanning microscopy. Hence, this study demonstrated that HANPs could be used to control the biofilm-related infections of P. aeruginosa

Fabrication of corrosion resistant, bioactive and antibacterial silver substituted hydroxyapatite/titania composite coating on Cp Ti

The present work is aimed at developing a bioactive, corrosion resistant and anti bacterial nanostructured silver substituted hydroxyapatite/titania (AgHA/TiO(2)) composite coating in a single step on commercially pure titanium (Cp Ti) by plasma electrolytic processing (PEP) technique. For this purpose 2.5 wt% silver substituted hydroxyapatite (AgHA) nanoparticles were prepared by microwave processing technique and were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM) methods. The as-synthesized AgHA particles with particle length ranging from 60 to 70 nm and width ranging from 15 to 20 nm were used for the subsequent development of coating on Cp Ti. The PEP treated Cp Ti showed both titania and AgHA in its coating and exhibited an improved corrosion resistance in 7.4 pH simulated body fluid (SBF) and 4.5 pH osteoclast bioresorbable conditions compared to untreated Cp Ti. The in vitro bioactivity test conducted under Kokubo SBF conditions indicated an enhanced apatite forming ability of PEP treated Cp Ti surface compared to that of the untreated Cp Ti. The Kirby-Bauer disc diffusion method or antibiotic sensitivity test conducted with the test organisms of Escherichia coli (E. coli) for 24 h showed a significant zone of inhibition for PEP treated Cp Ti compared to untreated Cp Ti. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Anti-Helicobacter pylori, cytotoxicity and catalytic activity of biosynthesized gold nanoparticles: Multifaceted application

An unpretentious way to synthesize different sized gold nanoparticles (GNPs) using the dried fruit extract of Tribulus terrestris has been investigated. GNPs were formed due to the reduction of chloroauric acid (HAuCl4) treated with the T. terrestris fruit extract. Formation of GNPs was periodically characterized by UV–Vis spectroscopy. IR spectrum revealed that phytochemicals in the extract played a key role in GNPs synthesis and stability. An anisotropic structure of GNPs with average sizes of 7 nm (GNP7) and 55 nm (GNP55) uses 1 and 2 mM HAuCl4. The biogenic GNP showed a size dependent anti-Helicobacter pylori activity against multidrug resistant H. pylori strains. Furthermore, biogenic GNPs possess an excellent catalytic activity for the reduction of a toxic, p-nitroaniline to p-phenylenediamine as non-toxic by-product. Interestingly, In vitro cell viability of GNP7 and GNP55 on AGS cell lines showed no toxicity at the MIC of H. pylori. The biogenic GNP has excellent biocompatibility, anti-H. pylori and catalytic properties of multifaceted biomedical applications