A novel acid-responsive polymer coating with antibacterial and antifouling properties for the prevention of biofilm-associated infections.

Chronic infections caused by the pathogenic biofilms on implantable medical devices pose an increasing challenge. To combat long-term biofilm-associated infections, we developed a novel dual-functional polymer coating with antibacterial and antifouling properties. The coating consists of N-vinylpyrrolidone (NVP) and 3-(acrylamido)phenylboronic acid (APBA) copolymer brushes, which bind to curcumin (Cur) as antibacterial molecules through acid-responsive boronate ester bonds. In this surface design, the hydrophilic poly (N-vinylpyrrolidone) (PVP) component improved antifouling performance and effectively prevented bacterial adhesion and aggregation during the initial phases. The poly (3-(acrylamido) phenylboronic acid) (PAPBA, abbreviated PB) component provided binding sites for Cur by forming acid-responsive boronate ester bonds. When fewer bacteria overcame the anti-adhesion barrier and colonized, the surface responded to the decreased microenvironmental pH by breaking the boronate ester bonds and releasing curcumin. This responsive mechanism enabled Cur to interfere with biofilm formation and provide a multilayer anti-biofilm protection system. The coating showed excellent antibacterial properties against Escherichia coli and Staphylococcus aureus, preventing biofilm formation for up to 7 days. The coating also inhibited protein adsorption and platelet adhesion significantly. This coating also exhibited high biocompatibility with animal erythrocytes and pre-osteoblasts. This research offers a promising approach for developing novel smart anti-biofilm coating materials.

[Experimental study of calcium phosphate cement mixed with bFGF and VEGF to repair bone defects in rabbit radius].

OBJECTIVE: To explore the synergistic effect of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) on the growth of bone tissue. METHODS: A total of 36 rabbits were randomly divided into 4 groups with 9 rabbits (18 sides of the anterior limb) in each group, including group A,B,C, and D. For all rabbits 1.0 cm bone defects was created in both sides of the radius. These bone defect regions were implanted with corresponding composites: group A with calcium phosphate cement (CPC) only, group B with CPC/bFGF, group C with CPC/VEGF while group D with both bFGF and VEGF. At the 3rd, 6th, and 12th week after the operation, 6 specimens from each group were randomly selected. The effects were partly assessed by X-ray film examination, bone mineral density (BMD) measurements, biomechanical test and histological observation. RESULTS: X-ray showed that at the 12th week the bone defects in group D were completely repaired with CPC generally degraded,whereas bone defects in group B and C were only basically repaired. BMD measurements showed that at the 12th week the BMD of group D was significantly higher than that of group B and C (P < 0.05). Biomechanical testing(at the 12th week) showed that the maximum bending load of group D was significantly higher than that of group B and C (P < 0.05). Histological observation indicated that at the 12th week, woven bone had become mature lamellar bone in group D. At the same time, the normal relation of cortical bone and marrow had resumed, and so had the normal structure of trabecula. However, the recanalization of bone marrow cavity could not be seen in group B and C. CONCLUSION: These 3 kinds of composite: CPC/bFGF, CPC/VEGF and CPC/ bFGF+VEGF can promote the growth of bone tissue and speed up the repair of bone defects. The composite of CPC/bFGF+VEGF is better than the other two composites in promoting the growth of bone tissues, indicating that bFGF and VEGF have a synergistic effect on the growth of bone tissue.