In situ loading of lipase onto polycaprolactone nanofibers via alternate electrospin-electrospray for enzymatic self-degradable air filtration membranes

Biodegradable nanofibers have been extensively explored, but their practical applications are usually impaired by the inconsistent decomposition rate, which is highly dependent on environmental conditions and variety of biological activities. Hence, development of self-biodegradable polymeric nanofibers through the incorporation of enzymes targeting the polymeric substrate could effectively regulate the degradation rate of nanofibrous matrix. Herein, this approach eliminates the need for enzyme protectants, which safeguard the enzyme activities in foreign environments. This study demonstrates the self-triggered degradation of the electrospun polymeric nanofibers via the action of enzymes embedded in situ within the nanofibrous matrix. An alternate electrospin-electrospray system was designed to blend lipase into the polycaprolactone (PCL) nanofiber matrix during the polymer electrospinning process. By varying the operating conditions of alternate electrospin-electrospray system, the influences on controlled biodegradation and the properties of the resultant nanofibrous scaffold were systematically studied. The feasibility of these lipase-embedded PCL nanofibers for use as face mask filter layers was denoted by the filtration efficiency at 91.37 %, aligning to the standards of commercial FFP1 respirators. PCL nanofibers containing 5 % w/w of immobilized lipase preserved the surface morphology and hydrophobicity properties of the control PCL nanofibers, while their complete biodegradation could be attained within 28 days. Filtration efficiency and biodegradability of the nanofibers also remained largely unaffected upon prolonged storage at room temperature, suggesting the stable incorporation of enzyme within PCL nanofiber matrix. This innovative approach of enzyme immobilization promises the controlled and efficient degradation of nanofibers after use, offering a sustainable remedy for face mask pollution.