In the present study, we prepared a gelatin nanofiber matrix using an electrospinning technique and cross-linked the nanofibers with 10 % glutaraldehyde vapors. The insoluble nanofibers were functionalized with bioactive molecules like biotin (1 %) and galactose (1 %) by adsorption and coelectrospinning. Surface morphology and fiber dimension were analyzed using atomic force microscopy. The amounts of biotin and galactose bound to the nanofibers before and after adsorption were quantified using high-performance liquid chromatography. Human larynx carcinoma (HEp-2) cell attachment, morphology and cytotoxic characteristics were studied using crystal violet staining and the MTT assay. Cell attachment and viability were highest in biotin- and galactose-embedded nanofibers compared to native nanofibers. Cytotoxicity was less with biotin- and galactose-embedded and adsorbed nanofibers compared to control nanofibers. Hence, we suggest that these biocompatible, nontoxic, biodegradable, functionalized nanofibers could be a potential candidate for application in tissue engineering and scaffold preparation.
Discovery of nanopillars on the surface of the insect wings had led to the understanding of its bactericidal property. Nanopillar topography is deterrent to only those bacteria that are attached, or in close contact with the nanopillars. The present study investigated the variation in the viability of Pseudomonas aeruginosa strains PAO1 (virulent) and ATCC 9027 (avirulent) on the wing surface of dragonfly (Pantala flavescens). Viability study indicated that only 0.2% ATCC 9027 survived when incubated with wing for 48 h in Phosphate buffered saline, while under the same conditions 43.47% PAO1 survived. Enumeration of Pseudomonas attached to wing surface suggested that, the number of PAO1 attached on the wing surface was three times lesser than ATCC 9027. Propensity of attachment of P. aeruginosa strains PAO1 and ATCC 9027 on the wing surface investigated using scanning probe microscope indicated that P. aeruginosa ATCC 9027 showed adhesion to 88% of regions and, PAO1 showed adhesion to only 48% regions tested on wing surface. PAO1 survived the bactericidal effect of wing surface by evading attachment. Three clinical isolates tested which showed viability similar to PAO1 strain, also showed lower propensity to attach to wing surface. Transcriptional level analyses using RT-PCR suggested that flagellar genes (fliE and fleS) were downregulated and genes responsible for reversible to irreversible attachment (gcbA and rsmZ) were upregulated in ATCC 9027 than PAO1 on wing surface, indicating relatively higher attachment of ATCC 9027 on wing surface. The study suggests that virulent strains of P. aeruginosa may evade attachment on wing surface. The results gain significance as bioinspired surfaces are being created towards developing antibacterial medical implants and other antibacterial surface applications.
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