One-pot synthesis of multipod Au-Cu nanocrystals with tunable branching for efficient photothermal treatment against multidrug-resistant bacteria

The plasmonic metal nanoparticle endowed with attractive localized surface plasmon resonance (LSPR) property is promising in the biomedical application. Herein, branched AuCu nanoalloys have been fabricated in one-pot, the morphology of which could be modified by altering the amine capping agent and thus obtaining monopods, tetrapods and pentapods nanostructure. Corresponding to nanoparticles with variable shape in aqueous solution, LPSR peaks were observed in the UV–vis extinction spectra, covering the visible region around 530 nm and the extended near-infrared (NIR) region at 780 nm and more than 1100 nm for AuCu nano-tetrapods and nano-pentapods respectively. The effective photothermal conversion is detected for the as-mentioned three nanostructures, among which AuCu nano-tetrapods and AuCu nano-pentapods achieved superb photothermal efficiency value under the 808-nm and 1064-nm laser irradiations, respectively, in consistence with their strong LPSR absorption wavelength around 780 nm and 1100 nm. Arising from such photothermal properties, the AuCu nano-tetrapods exhibited excellent antibacterial efficiency with minimal inhibitory concentration (MIC) of 29.3 μg mL−1 and facilitated to inhibit a wide range of multidrug-resistant bacteria.