This is likely due to the synergistic effects caused by the reduced chlorine content, as well as the reduced surface interactions with the microbes. In contrast, the surface modified with N-halamine only exhibited significantly less antimicrobial efficacy instead. All of these hydrophilic monomer-containing N-halamine-modified PU substrates demonstrated a more than 2 log CFU reduction after microbial incubation. The degree of chlorination was improved with the introduction of a hydrophilic monomer, except the HEMA.
It was noted that the chains containing the hydrophilic monomer and the polymerizable N-halamine compound were successfully grafted onto the PU substrate. Further, using the sequential SI-ATRP reaction method, different hydrophilic monomers, namely poly (ethylene glycol) methacrylate (PEGMA), hydroxyethyl methacrylate (HEMA), and dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA), were also grafted onto the polyurethane (PU) substrate before the N-halamine grafting reaction to change the surface properties of the N-halamine-modified substrate. In this study, a polymerizable N-halamine compound was synthesized and grafted onto a polyurethane surface via a surface-initiated atom transfer radical polymerization (SI-ATRP) scheme. Nevertheless, the hydrophobic nature associated with its chemical configuration may affect the microbial interactions with the chlorinated N-halamine-containing substrate. Surface grafting or coating of N-halamine was also reported. It can be incorporated into or blended with the FDA-approved biomaterials. Due to its stability and low toxicity, the N-halamine compound has been proposed as a potential antimicrobial agent.
Reducing microbial infections associated with biomedical devices or articles/furniture noted in a hospital or outpatient clinic remains a great challenge to researchers.