Screening enzymatic degradation of polyester polyurethane with fluorescent single-walled carbon nanotube and polymer nanoparticle conjugates

Abstract

Enzymatic biodegradation is a promising method to reclaim waste plastic materials. However, to date, a high throughput method for screening potential enzyme candidates for biodegradation is still lacking. Here, we propose a single-walled carbon nanotube (SWCNT) fluorescence sensor for screening enzymatic degradation of polyester polyurethane nanoparticles. Through wrapping the SWCNT with cationic chitosan, an electrostatic bond is formed between the SWCNT and Impranil, a widely applied model substrate of polyester polyurethane. As Impranil is being degraded by the enzymes, a characteristic quenching at the short reaction time followed by a brightening at the longer reaction time in the fluorescence signal is observed. The time-dependent fluorescence response is compared with turbidity measurement, and we conclude the brightening in fluorescence results from the binding of the degradation product with the SWCNT. The proposed SWCNT sensor design has potential to screen enzyme candidates for selective degradation of other plastic particles.