[Biocompatibility assessment of a PDMS-CHXG antibacterial coating on titanium]

To evaluate the biocompatibility of polydimethylsiloxane-chlorhexidine (PDMS-CHXG) coatings constructed on titanium surfaces.

Titanium discs were modified with a PDMS coating, onto which CHXG was grafted at concentrations of 0.4, 0.8, and 1.6 mg/mL. The samples were randomly divided into 5 groups: Ti group (the control group), P group (PDMS only), C1 group (PDMS with 0.4 mg/mL CHXG), C2 group (PDMS with 0.8 mg/mL CHXG) and C3 group (PDMS with 1.6 mg/mL CHXG). Surface characteristics were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). In vitro biocompatibility was assessed using human gingival epithelial cells through cytoskeleton staining, live/dead staining, and CCK-8 assays to evaluate cell viability, adhesion, and proliferation, respectively. For in vivo evaluation, the samples were implanted subcutaneously in Sprague-Dawley rats, and the surrounding tissue response was analyzed by HE staining.

Successful fabrication of the PDMS-CHXG coating was verified, with a positive correlation observed between chlorine content and CHXG concentration. While the Ti, P, C1 and C2 groups showed robust cell health and proliferation with normal morphology, the C3 group led to reduced viability, poor adhesion, and proliferative suppression. Accordingly, in vivo data indicated minimal inflammation and similar, thin fibrous capsules for Ti, P, C1 and C2 implants, whereas the C3 group provoked a pronounced inflammatory response with significant fibrous capsule thickening.

The study confirms that a PDMS-CHXG coating with a CHXG concentration of ≤0.8 mg/mL exhibits excellent overall biocompatibility.