Biofunctionalization of Titanium Implants Loaded with Dimethylaminododecyl Methacrylate Against Infections

Objectives: The aim of this study was to investigate the bio-function of dimethylaminododecyl methacrylate (DMADDM) delivery via titanium implant and its prophylaxis potential against implant infection.
Methods: Antimicrobial effects of DMADDM-loaded titanium (Ti-DMA) implants were tested (n=6). Changes in mechanical properties, antibacterial effects, cytotoxicity and osteogenesis were evaluated after biodegradation by Staphylococcus aureus (S. aureus) (n=6). In vivo compatible properties were verified (n=5) and effectiveness of Ti-DMA in a rat femur osteomyelitis model was investigated (n=5).
Results: Comparing with pure titanium (Ti), with 4 weeks of release, both DMADDM remaining on titanium surface and released into soaking medium could effectively reduce the adherence and growth of S. aureus, Staphylococcus epidermidis (S. epidermidis) and Enterococcus faecalis (E. faecalis) (P<0.05). With the release of DMADDM, the antibacterial effect of Ti-DMA was weakened (P<0.05), but it promoted osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) (P<0.05) with much lowered cytotoxicity (P<0.01). Hemoglobin of rats after Ti and Ti-DMA implantation was at the same level (mean±sd; n=5): (160.6±6.6)g/L, (156.2±8.7)g/L at 3 weeks, (153.6±6.6)g/L, (150.6±2.7)g/L at 6 weeks, respectively. Body weight, neutrophil count and osseointegration of the two groups were similar (P>0.05). In addition, Ti-DMA could effectively prevent bone destruction in rat osteomyelitis model (P<0.05). Compared with the negative control group, the log-reduction of S. aureus on Ti-DMA and around the bone were 1.77-log and 1.52-log. At 6 weeks, the mean bone volume fraction (BV/TV) of contaminated Ti and Ti-DMA were 0.67±0.11, and 0.67±0.04, compared with 0.42±0.08 for negative control. The trabecular thickness (Tb.Th) was 0.52±0.12, 0.56±0.02 and 0.29±0.09, respectively.
Conclusions: Ti-DMA implants provided antibacterial effects during the high-risk period of infection with DMADDM release. Ti-DMA implants subsequently enabled osseointegration, making them promising candidates for high-risk infection conditions to combat implant infections.