Cysteamine: A key to trigger aggregation-induced NIR-II photothermal effect and silver release booming of gold-silver nanocages for synergetic treatment of multidrug-resistant bacteria infection

Abstract

Gold silver nanocages (GSNCs) have been applied as an excellent nano-cargo for drug delivery and near infrared (NIR) photothermal therapy due to their tunable optical properties and biocompatibility. However, a dilemma is that GSNCs with NIR adsorption normally have a highly-hollow silver core and thick gold coating, which largely mitigates the antibacterial activity because of the limited use of contained silver species. Here we have proposed an alternative strategy on basis of the aggregation induced photothermal (AIP) effect by the combination of high silver-loading GSNCs and thiolates. Interestingly, a typical thiolate, cysteamine, was found to rapidly induce the release of ultrasmall silver alloy species from GSNCs, with at least 4 fold amount compared with that by other thiolates. The booming silver release from GSNCs and NIR photothermal effect synergistically allow the removal of the biofilm secreted by multidrug resistant (MDR) bacteria in vitro and the eradication of MDR S. aureus in infection wound of mice. This strategy may provide a promising method for effective treatment of intractable MDR bacterial infection.