Covalent Grafting of Quaternary Ammonium Salt-Containing Polyurethane onto Silicone Substrates to Enhance Bacterial Contact-Killing Ability.

Catheter-associated urinary tract infection (CAUTI) induced by rapid bacterial colonization and biofilm formation on urinary catheters is a key issue that urgently needs to be addressed. To prevent CAUTI, many contact-killing, non-leaching coatings have been developed for the surfaces of silicone catheters. However, due to the chemical inertness of the silicone substrate, most current coatings lack adhesion and are unstable under external forces. Thus, the aim of this study was to develop a surface coating that has both good antibacterial ability and a high affinity toward silicone substrates. To achieve high affinity, a pre-coating layer with abundant surface vinyl groups, named SI-vinyl, was prepared on the silicone substrate by moisture curing using a mixture of α,ω-dihydroxy polydimethylsiloxane and vinyltrimethoxysilane as the painting agent. To endow the surface with contact-killing ability, a series of polyurethanes with different contents of quaternary ammonium salt groups in their main chain and two vinyl end groups were synthesized and covalently grafted onto the surface of SI-vinyl, resulting in corresponding bactericidal coatings with different surface contents of quaternary ammonium salt groups (SI-QAS). Of these bactericidal coatings, SI-QAS-2, with a surface QAS content of 2.1 × 10