Giant (Jun 2022)
Photo‐triggered polymeric antimicrobial peptide mimics with excellent selectivity and antifouling and antimicrobial hydrogels
Abstract
Stimuli-responsive antimicrobial polymeric materials have received increasing interest. In this study, we synthesized a novel type of photoresponsive antimicrobial poly(ethyl glycol)-b-poly[N-[2-[N-(o-nitrobenzyloxycarbonyl)-amino]-ethyl]-glycine] (PEG-b-PN(oNB)G) diblock copolymer by ring-opening polymerization. Upon UV irradiation, the amine groups can be generated due to the photocleavage of the o-nitrobenzyl protecting groups. The cleavage degree can reach up to around 90% after 12 h UV irradiation. The copolymers exhibit excellent antimicrobial activity with a low minimal inhibitory concentration (MIC) value after UV irradiation. We demonstrate that this is possibly because of the balance of hydrophobicity and amphiphilicity arising from the remaining hydrophobic phenyl residues, which structurally mimic antimicrobial peptides (AMPs). We further demonstrate a disrupted cell membrane mechanism mimetic to AMPs by systematic studies of cytoplasmic membrane depolarization assay, cytoplasmic membrane permeabilization assay, bacterial morphology, and the interaction between the irradiated copolymer and the bacterial membrane by confocal laser scanning microscopy (CLSM). Remarkably, the obtained copolymers show excellent selectivity with extremely high HC5 values (> 2000 μg/mL). In addition, the photoresponsive polymers exhibit remarkable antimicrobial activity against multidrug-resistant S. aureus (MRSA), and high efficiency to inhibit the formation of MRSA biofilms and eradicate the mature MRSA biofilms. Further, we prepared the photoresponsive hydrogels by mixing with agarose, which results in a recyclable antimicrobial and nonfouling surface. The photoresponsive AMP-mimetic polymers and the biocompatible hydrogels with dual-functionalities show great potential for antimicrobial applications.
