International. A new study shows that the adhesion strength between metal-based antibacterial coatings and the polymer substrate decides the effectiveness and durability of antibacterial performance.
The silicone rubber substrate was modified by a molecular bridge, i.e. polyvinylpyrrolidone, chitosan and (3-mercaptopropyl) trimethoxysilane, to provide "anchors" that captured Ag+ during electrolytic coating, and Ag coatings were produced.
Extended plate count, fluorescent staining assay and bacterial growth kinetics showed that antibacterial and anti-biofilm performance against Escherichia coli and Staphylococcus aureus was directly related to the adhesion strength between the coating and the substrate. Relatively weak adhesion resulted in a rapid inhibition effect of bactericidal and bacterial growth, and vice versa.
Inductively coupled plasma atomic emission spectrometry indicated that relatively weak adhesion provided rapid release of Ag+, and strong adhesion gave a lower cumulative concentration of Ag+, which can be attributed to a different binding force. The coatings showed sustained-release kinetics with the maximum cumulative Ag+ concentration of just 0.45 mg/L after 45 days of immersion in PBS solution, which was well below the toxicity concentration of human cells.
However, all Ag coatings tested showed effective and long-lasting antibacterial properties. The adapted adhesion and the consequent antibacterial effect provided an option for clinical applications.
Source: Journal of Materials Science.
