Preparation And Characterization Of Rana Chensinensis Skin Extracts/poly(ε-caprolactone) Electrospun Membranes As Antibacterial Fibrous Mats

In this study, Rana chensinensis skin extracts (RCSEs) were preparated from thewaste Rana chensinensis skin by grinding, hydrolysis, and freeze-dried progress.Rana chensinensis skin was purchased from the local market as raw materials. InOrder to determine the optimum extraction, the extraction process of RCSEs wascharacterized by three experiments, which were subjected to three factors as acidconcentration, extraction time, and solid-liquid ratio. As a potential antibacterialpackageing material for practical applications, the antibacterial efficiencies of RCSEswere quantitatively evaluated to the Gram-positive bacteria Staphylococcus andGram-negative bacteria Escherichaia coli, with the viable cell-counting method. Inaddition, membranes composed of RCSEs and poly(-caprolactone)(PCL) werefabricated by an electrospinning technique. The membranes were characterized byscanning electron microscopy, Fourier transform infrared spectroscopy, mechanicaltests, hydrophilic performance test, and antibacterial evaluation.From the results of the extraction process experiments, the acid concentrationand the extraction time had a proportional relationship with the extraction rate ofRCSEs, on the other hand, the solid-liquid ratio had a inverse relationship with theextraction rate of RCSEs. The optimal concentration of acid solution was5%, the bestextraction time was24h, and the best solid-liquid ratio was1/60.The results of SEM show that fractured and irregular fibers were clearlyobserved when the PCL content in the RCSE/PCL blend was less than30%w/w. Withincreasing PCL content in the electrospun scaffold fibers, the amount of surfaceroughness and irregular fibers clearly decreased, and the fibers became smooth and straight. In the mechanical tests, the scaffold prepared from pure RCSEs had lowermechanical tensile properties. The strength, toughness, and elastic deformation abilityof the membranes increased with increasing PCL content in the electrospun fibermembranes. The elongation at break increased significantly (p<0.05) when the ratiosreached60:40.The contact angle measurement of RCSEs/PCL electrospun membranes,the membrane show the best performance of hydrophilic when the RCSEs/PCL ratiosreached60:40. Corresponding to FTIP data analysis, we consider this may due to theinteraction between RCSEs and PCL promoted the release of free state of N-Hgroups.From the results of antibacterial evaluation, The Grampositive bacteriaStaphylococcus aureus (a suspension of5×107cfu/mL) and Gram-negative bacteriaEscherichia coli (a suspension of5×107cfu/mL) were used as the model organisms.RCSEs had good antibacterial activity against S. aureus and E. coli. As to S. aureus,the antibacterial rate increased rapidly when the contact time was less than3h, and itremained between40%-60%when the contact time was more than3h. As to the E.coli, the antibacterial increased in the first12h, and it reached higher than50%whenthe contact time was more than12h.For RCSEs/PCL electrospun membranes, the antibacterial efficiency increasedwith higher contention of RCSEs, and the antibacterial rate reached60.4%(S. aureus),and40.8%(E. coli). However, the presence of PCL in the RCSE/PCL membranesimproved the mechanical properties, and the presence of RCSEs improved theantibacterial activity of the membranes. Thus, these membranes could serve as a goodfood storage and packaging material.