Safety Considerations for Lyophilized Human Amniotic Membrane Impregnated with Colistin and Silver Nanoparticles.

Lyophilized human amniotic membrane (HAM) and silver nanoparticles (AgNPs) have multispectral applications as a biological dressing. The present study focuses on the safety aspects of HAM coated with colistin and AgNPs (HACoN) dressing in relation to its structural and hematological changes. Four dressing groups were designed for the study, HAM, HAM coated with colistin (HACo), HAM coated with AgNPs (HAN), and HAM coated with colistin (HACo) and HACoN. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were utilized for constitutional analysis. Biological safety was checked by applying HAM of all groups on open excisional burn wounds on Sprague-Dawley rats for 21 days. The skin, kidneys, liver, and spleen were removed, and histological analysis was performed for detailed structural analysis. Oxidative stress was assessed using homogenate from newly generated skin. No structural or biochemical change was observed in any of the study groups as observed by SEM and FTIR. After 21 days of grafting, wounds were healed properly with normal skin, and no anomaly was observed in related to kidneys, spleen, and liver. Some of antioxidant enzymes were increased, while malondialdehyde which is a reactive oxygen species was reduced in the skin tissue homogenate of HACoN group. Impregnation of colistin and AgNPs in combination on HAM has no effects on hematological and structural constitution of HAM. It leaves no obvious change in vital organs of rats and improves oxidative stress and inflammation. Hence, it can be claimed that HACoN is a biologically safe antibacterial dressing.

Synergistic efficacy of colistin and silver nanoparticles impregnated human amniotic membrane in a burn wound infected rat model.

Antimicrobials used to treat burn wound infections have become multidrug-resistant, thus delaying wound healing. When combined with silver nanoparticles, antibiotics create a multifaceted antibacterial mechanism of action to which bacteria are incapable of developing resistance. Similarly, the amniotic membrane has been found to lower the bacterial number. The purpose of the current study was to observe the antibacterial activity of combined topical colistin with silver nanoparticles and decellularized human amniotic membrane as a dressing in burn wounds infected with bacteria with the goal of promoting faster healing. Bacteria commonly isolated from burn wounds and the most sensitive topical antibiotic were identified. Colistin, silver nanoparticles and combined colistin with silver nanoparticles were impregnated into decellularized human amniotic membranes. These wound dressings were evaluated in third-degree multidrug-resistant bacterial infected thermal burns induced in rats. Out of a total of 708 pus samples from burn wounds, Pseudomonas aeruginosa was the most prevalent pathogen 308 (43.5%), followed by Klebsiella pneumoniae 300 (42.4%). Topical colistin was 100% sensitive for both bacteria. Overall, maximum wound contraction (p < 0.05), and increased collagen deposition (+++) with no isolation of bacteria from wound swabs were noted on day 21 for the combined colistin with silver nanoparticle-loaded human amniotic membrane dressing group. Our study concluded that the increased antimicrobial activity of the novel combination of colistin and silver nanoparticle-loaded decellularized human amniotic membrane manifested its potential as an effective burn wound dressing.

Evaluating the Potential of Oleaginous Yeasts as Feedstock for Biodiesel Production.

BACKGROUND: Lipid-producing microorganisms, said to be oleaginous have been recognized since several years. We had investigated the effects of medium components and culturing situations on cell growth and lipid accumulation of oleaginous yeasts which were analytically examined so as to enhance lipid yield for biodiesel production. OBJECTIVE: The main objective of this study was to explore oleaginous yeast, Yarrowia lipolytica isolated from soil and optimization of culture conditions and medium components to obtained better quality microbial oil for biodiesel production. METHODS: Fifty yeast strains were isolated from soil from different regions of Lahore and eleven of them were selected for oil production. The isolated yeast colonies were screened to further check their lipid producing capabilities by the qualitative analysis. Five yeast strains were designated as oleaginous because they produced more than 16% of oil based on their biomass. To estimate the total lipid content of yeast cells, the extraction of lipids was done by performing the procedure proposed by Bligh and Dyer. The transesterification of yeast oils was performed by using different methods. There were three different strategies customized to transesterifying microbial oil using base catalyzed transesterification, acid catalyzed transesterification and enzyme-based transesterification. After completion of transesterification, sample was used for fatty acid methyl esters (FAMEs) were analyzed by gas-chromatograph with ionization detector type MS. RESULTS: The isolate IIB-10 identified as Yarrowia lipolytica produced maximum amount of lipids i.e. 22.8%. More amount of biomass was obtained when cane molasses was utilized as carbon source where it produced 29.4 g/L of biomass while sucrose and lactose were not utilized by IIB-10 and no biomass was obtained. Similarly, meat extracts showed best results when it was used as nitrogen source because it resulted in 35.8 g/L biomass of Yarrowia lipolytica IIB-10. The culturing conditions like size of inoculum, effect of pH and time of incubation were also studied. The 10% of inoculum size produced 25.4 g/L biomass at 120 h incubation time, while the pH 7 was the optimum pH at which 24.8 g/L biomass was produced by Yarrowia lipolytica IIB-10. GC-MS analysis showed that biodiesel produced by transesterification contained similar fatty acids as found in vegetable oil for this reason it is widely accepted feedstock for biodiesel production. CONCLUSION: The analysis of fatty acids methyl esters showed the similar composition of microbial oil as in vegetable oils and high amount of methyl esters were obtained after transesterification. Therefore, potentially oleaginous yeast could be used to generate a large amount of lipids for biodiesel production that will be the better substitute of petroleum-based diesel and will also control the environmental pollution.