In situ formation of antimicrobial silver nanoparticles and the impregnation of hydrophobic polycaprolactone matrix for antimicrobial medical device applications

• Ag–PCL composites were created with highly dispersed Ag nanoparticles.
• The synthesis method is simple, in situ and at room temperature.
• All composites showed strong antimicrobial activity against S. aureus and P. aeruginosa.
• The composites also significantly inhibited biofilm formation of the two bacteria.
• The prolonged release of Ag from the composite could be readily tailored.

Bacterial infection associated with medical devices remains a challenge to modern medicine as more patients are being implanted with medical devices that provide surfaces and environment for bacteria colonization. In particular, bacteria are commonly found to adhere more preferably to hydrophobic materials and many of which are used to make medical devices. Bacteria are also becoming increasingly resistant to common antibiotic treatments as a result of misuse and abuse of antibiotics. There is an urgent need to find alternatives to antibiotics in the prevention and treatment of device-associated infections world-wide. Silver nanoparticles have emerged as a promising non-drug antimicrobial agent which has shown effectiveness against a wide range of both Gram-negative and Gram-positive pathogen. However, for silver nanoparticles to be clinically useful, they must be properly incorporated into medical device materials whose wetting properties could be detrimental to not only the incorporation of the hydrophilic Ag nanoparticles but also the release of active Ag ions. This study aimed at impregnating the hydrophobic polycaprolactone (PCL) polymer, which is a FDA-approved polymeric medical device material, with hydrophilic silver nanoparticles. Furthermore, a novel approach was employed to uniformly, incorporate silver nanoparticles into the PCL matrix in situ and to improve the release of Ag ions from the matrix so as to enhance antimicrobial efficacy.