Development of biodegradable particulate filters incorporating immobilized proteinase K in Poly(L-lactic acid) for use in respirator face masks

Abstract

In recent years, the COVID-19 pandemic and PM 2.5 pollution have been shown to cause respiratory health problems. The number of disposable face masks used in the world has resulted in a huge quantity of environmental waste since the materials are non-biodegradable polymers. Therefore, the aim of this study is to fabricate self-biodegradable nanofibrous particulate filters. Poly(L-lactic acid) (PLLA) was the material selected and was blended with synthesized oligomeric lactic acid (OLA) to improve the mechanical properties of the PLLA. The results showed that adding OLA reduced the glass transition temperature (Tg) of the PLLA from 58 to 49 °C, while tensile testing confirmed that the strength and elasticity of PLLA/OLA blends was better than that of PLLA alone. A typical degradation period for biodegradable polymers is several months under composting conditions. However, depolymerase can accelerate the decomposition of polymers. One of the most interesting enzymes for this purpose is proteinase K (ProK). Moreover, to promote antimicrobial properties, Titanium dioxide (TiO2) was used to be an additive. In this work, ProK and TiO2 were incorporated into the PLLA/OLA blends via emulsion electrospinning to produce nano-sized fibers. From the experiment, fabricated fibers have the least fibers diameter at 512.34 ± 0.11 nm and least pore size 0.277 µm. Decreasing of pH value and weight of electrospun nanofibers confirmed that the ProK can accelerate the degradation of PLLA. Therefore, the addition of TiO2 can promote ProK mechanism and increase degradation rate of PLLA more. However, the amount of TiO2 that was used in this study is not

inhibition. From the results obtained, particulate filter fibers were successfully obtained showing self-biodegradation. This promoted the PLLA degradation without the need for composting and reducing the amount of waste that accumulates in the environment and have high the particulate filtration efficiency (PFE) about 64-80% with remaining high quality for 3 months when keep it at room temperature.