Silicone rubber films functionalized with poly(acrylic acid) nanobrushes for immobilization of gold nanoparticles and photothermal therapy

Prevention and treatment of medical device-related infections demands novel strategies for hindering bacteria adhesion and proliferation. The aim of this work was to immobilize gold nanoparticles onto silicone rubber (SR) and then exploit the plasmon resonance properties for the photothermal killing of adhered bacteria. To obtain a good rate of gold deposition, SR films were grafted with PAAc nanobrushes (SR-g-AAc) using a Co-60 gamma source. Effects of absorbed dose, monomer concentration, temperature and reaction time on the grafting percentage, swelling and mechanical properties of the films were first investigated. Gold nanoparticles were immobilized on SR and SR-g-AAc following different strategies. Immersion in gold ions (HAuCl4) solution and subsequent reduction made the films to be uniformly coated by 10-20 nm gold nanoparticles as shown by SEM-EDX and XRD. Photothermal features were evidenced as an increase in 6-7 degrees C in the first 5 min of irradiation with a 514 nm laser at a power density of 0.5 W/cm(2). Finally, SR-g-AAc films were challenged against Staphylococcus aureus and effects of irradiation at 514 nm on bacteria survival evaluated. Overall, the gold-immobilized films were shown to be stable against autoclave sterilization and ultrasounds and exhibited outstanding ability to damage adhered bacteria after laser irradiation. (C) 2017 Elsevier B.V. All rights reserved.