Enhancing lubricity and biocompatibility of PA12 catheters by surface modification using epichlorohydrin and polyethyleneimine.

Medical nylon catheters (PA12) are essential instruments in interventional procedures, yet their inherent surface hydrophobicity and limited lubricity significantly restrict clinical performance. Although various hydrophilic coatings have been developed to address these issues, traditional physical coating methods often suffer from poor adhesion and delamination during use. To overcome these drawbacks, we developed a two-step chemical modification strategy involving epichlorohydrin (ECH) activation followed by covalent grafting of polyethyleneimine (PEI), aiming to construct a stable hydrophilic lubricating layer on PA12 catheter surfaces. XPS analysis revealed a marked change in the surface chemical composition, indicating the successful covalent grafting of PEI. The modified catheter exhibited a surface amino group density of 2.7229 µmol mm-2, approximately four times higher than that of the pristine PA12 catheter, indicating the successful grafting of PEI molecules onto the catheter surface. This modification markedly enhanced surface hydrophilicity, reducing the water contact angle from 103.54° to 62.01°, decreasing the friction coefficient by 36.9%, and nearly doubling water absorption. Moreover, the modified catheter displayed promising in vitro biocompatibility, as evidenced by non-cytotoxic extracts, a hemolysis rate of only 0.65%, and no detectable adverse effects on blood cell counts. Overall, this study presents a covalent grafting-based surface functionalization strategy for PA12 interventional catheters that improves both lubricity and surface hydrophilicity while retaining in vitro biosafety. These findings provide a basis for future investigations into the long-term stability and in vivo performance of the modified catheters.