Enhanced productivity of electrospun polyvinyl alcohol nanofibrous mats using aqueous N,N-dimethylformamide solution and their application to lipase-immobilizing membrane-shaped catalysts

Electrospun polyvinyl alcohol (PVA) nanofibrous non-woven fabrics have been widely used for cell and enzyme immobilization. Enhancement of the productivity of the material will further enlarge the versatility of them. In this study, a mixture of water and N,N-dimethylformamide (DMF) was used as a solvent of PVA. The productivity defined as ([1 − (amount of polymer which did not come in contact with the collector)/(amount of polymer ejected from the needle for 30 min)] × 100) of electrospun PVA fibers increased from 15 to 92% by increasing the content of DMF from 0 to 10 wt%. As a potential application of the electrospun PVA fibers prepared by the enhanced production system, we encapsulated Burkholderia cepacia (formerly, Pseudomonas cepacia) lipase in the fibers by including lipase powder in the PVA solution before electrospinning, and evaluated catalytic performance of the resultant fibrous catalysts in organic solvent. The lipase encapsulated in the PVA fibers produced from a solution of water and 10 wt% DMF showed a 1.5-fold increase in initial reaction rate in the transesterification of (S)-glycidol and vinyl butyrate to produce (S)-glycidyl butyrate than that encapsulated in the PVA fibers obtained from the solvent without DMF, i.e., water. These findings demonstrate the practicality of the proposed system to enhance the productivity of electrospun PVA fibrous matrices for extended applications of the resultant fibers including the usage as carriers enclosing lipase for reactions in organic solvents.