Tunable functionalization of poly(ethylene terephthalate) with short-chained quaternary ammonium salt and N-chloramine to enhance conversion of N-H to N-Cl and the antibacterial activity of the resulting N-Cl

Abstract

Cross-contamination mediated by fomites such as textiles has been identified as one of the major pathways of infectious disease transmission. It is therefore critical to endow those substrates with rechargeable potent antimicrobial activity. N -chloramines, compounds with N-Cl bonds, are a typical group of broad-spectrum effective antimicrobials. Once immobilized onto a substrate, N -chloramines can attain repeated cycles of killing pathogens (loss of active chlorine) and regeneration (recovery of the original N -chloramine structure). However, relatively high levels of free chlorine are needed to recharge the biocidal function on N -chloramine containing textile substrates especially on such hydrophobic ones such as poly(ethylene terephthalate) (PET). We found the introduction of a short-chained quaternary ammonium group to N -chloramines could lead to higher conversion rate of surface bound N-H to N-Cl. Here, we separately clicked an azido N -chloramine precursor (AzH) and a short chain QAS (AzQAS) onto a previously established clickable PET platform to explore the effect of such surface bound QAS on the conversion of surface N-H to N-Cl and the antibacterial activity of the resulting N-Cl. Despite not being covalently bonded to hydantoin, the source of a cyclic N-H, the positive charge center dramatically facilitates the conversion of the hydantoin N-H to N -chloramine in dilute chlorine bleach (<250 ppm Cl 0 ). At a 5 0 :50 ratio to the cyclic N -chloramine precursor (hydantoin), the surface bound QAS enables the PET substrate, after being activated with dilute chlorine bleach (100 ppm Cl 0 ), to achieve 5.81 log reduction of MDR- E. coli within 10 minutes of contact. • A new way to achieve tunable functionalization of poly(ethylene terephthalate) (PET) with short-chained quaternary ammonium salt (QAS) and N-chloramine at varying ratios • Despite being separately bonded to PET surface with an N-chloramine precursor hydantoin, a quaternary ammonium molecule can dramatically facilitate the conversion of the hydantoin N-H to N-chloramine in dilute chlorine bleach (<250 ppm Cl0). • At a 50:50 ratio to the cyclic N-chloramine precursor (hydantoin), the surface bound QAS enables the PET substrate, after being activated with dilute chlorine bleach (100 ppm Cl0), to achieve 5.81 log reduction of MDR-E. coli within 10 minutes of contact. • Positive charge contributes to faster killing of MDR-E. coli by N-chloramine immobilized on PET.