Construction of cationic conjugated microporous polymers containing pyrene units through post-cationic modification for enhanced antibacterial performance

Abstract

BackgroundThe development of effective antibacterial agents with minimal cytotoxicity to human cells is a subject of great interest. Conjugated microporous polymers (CMPs) are a rapidly expanding and significant class of porous organic polymers. They are distinguished by their robust microporous architecture and π-conjugated framework. The molecular-level control over the pore structure and chemical composition of CMPs allows for precise customization to fulfill particular requirements. MethodsWe synthesized a cationic conjugated microporous polymer named Pyr-T-DPM Me CMP. This was achieved through post-synthetic modification of a pyrene-T-linked conjugated microporous polymer, Pyr-T-DPM CMP, formed via the Sonogashira coupling reaction of ethynyl pyrene (Pyr-T) and 2,5-dibromopyrimidine (Pyrimidine-Br2). The comprehensive analysis involved various techniques, including Fourier transform infrared (FTIR) spectroscopy, N2 adsorption/desorption isotherm, 13C solid-state NMR, X-ray photoelectron spectroscopy (XPS), thermogravimetry, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Significant findingsThe antimicrobial efficacy of the newly synthesized CMPs was tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. Due to the formation of N-methylpyrimidinium salts after quaternization, the cationic Pyr-T-DPM Me CMP exhibited enhanced bactericidal effectiveness against S. aureus compared to Pyr-T-DPM CMP, which lacked a positive charge. The viability of bacteria decreased with increasing concentrations of Pyr-T-DPM Me CMP, reaching maximum antimicrobial effectiveness at a concentration of 5 mg mL−1. To assess their impact on cell compatibility, we evaluated the cytotoxic effects on L929 cell fibroblasts, revealing minimal cytotoxicity towards L929 cells. Inspired by the superior antibacterial characteristics and exceptionally low toxicity of Pyr-T-DPM Me CMP, the novel cationic CMP developed in this study holds potential for application as beneficial antibacterial agent in the fields of environmental engineering and healthcare.