Immobilization of trypsin onto poly(ethylene terephthalate)/poly(lactic acid) nonwoven nanofiber mats

• Electrospun PET/PLA nonwoven nanofibrous mats were used for trypsin immobilization.
• Best immobilization method: covalent attachment of crosslinked trypsin aggregates.
• Immobilized trypsin had good storage/operational stability.

Mixed solutions of poly(ethylene terephthalate) (PET) and three types of poly(lactic acid) (PLA; a commercial sample and two branched PLAs) were used to prepare nonwoven nanofibrous mats by electrospinning. These mats were used as supports for trypsin immobilization, with the aim of an application in whey protein hydrolysis. Covalent attachment of crosslinked trypsin aggregates to amine-derivatized PET/PLA mats, followed by reduction with sodium cyanoborohydride, gave the best immobilized trypsin activity and showed no enzyme leaching. The activity of immobilized trypsin was higher than that of free trypsin at pH 6, a pH value representative of sweet whey. The PET/PLA mats with immobilized trypsin could be stored at 4 °C in water for at least 30 days, and could be reused 8 times without loosing activity and without enzyme leaching.

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