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The development and application in different fields of multifunctional plasmonic nanoparticles (NPs) have always been research hotspots. Herein, multi-tip Au nanostars (NSs) with an anisotropic structure were fabricated for the photothermal therapy (PTT) of bacteria and surface-enhanced Raman scattering (SERS) detection of pollutants. The size and localized surface plasmon resonance (LSPR) characteristics of Au NSs were adjusted by varying Au seed additions. In addition, photothermal conversion performance of Au NSs with various Au seed additions was evaluated. Photothermal conversion efficiency of Au NSs with optimal Au seed additions (50 μL) was as high as 28.75% under 808 nm laser irradiation, and the heat generated was sufficient to kill Staphylococcus aureus (S. aureus). Importantly, Au NSs also exhibited excellent SERS activity for the 4-mercaptobenzoic acid (4-MBA) probe molecule, and the local electromagnetic field distribution of Au NSs was explored through finite-difference time-domain (FDTD) simulation. As verified by experiments, Au NSs' SERS substrate could achieve a highly sensitive detection of a low concentration of potentially toxic pollutants such as methylene blue (MB) and bilirubin (BR). This work demonstrates a promising multifunctional nanoplatform with great potential for efficient photothermal inactivation and ultra-sensitive SERS detection. [ABSTRACT FROM AUTHOR]

Tetracycline (TC) is widely distributed in environment and a significant environmental pollutant. It has been challenging to rapidly identify and effectively remove TC contaminants. This work produced a multifunctional Fe 3 O 4 -Cu 2 O-Au-MIPs nanocomposite (FCAu-MIPs NCs) based on molecular imprinting technology for selective SERS detection and photocatalytic degradation of TC. We synthesized FCAu NCs with various Au contents and analyzed the relationship between Au content and SERS performance using finite-difference time-domain (FDTD) technique. Exceptional SERS performance could be attributed to the dense distribution of multiple hotspots on the SERS substrate. The photocatalytic mechanism of FCAu-MIPs NCs towards TC was also discussed. The combination of the narrow-bandgap semiconductor Cu 2 O and noble metal Au with localized surface plasmon resonance (LSPR) effect facilitated efficient light absorption and enhanced charge carrier transfer efficiency. Both SERS detection limits as low as 10−9 M and selective photocatalytic degradation of TC in soil were achieved. Furthermore, FCAu-MIPs NCs were successfully recovered and reused with assistance of external magnetic field. After six cycles, outstanding SERS and photocatalytic capacities from FCAu-MIPs NCs could still be maintained. The FCAu-MIPs NCs with selective recognition ability to TC should thus hold tremendous applicative possibilities for highly sensitive detection and efficient degradation of TC. [Display omitted] • A novel Fe 3 O 4 -Cu 2 O-Au-MIPs was successfully constructed. • The effect of gold content on SERS performance was simulated by FDTD method. • Integration of targeted degradation and specific SERS detection by FCAu-MIPs. • Electron transfer mechanism between Cu 2 O and Au nanocrystals was analyzed. • Limit of detection of FCAu-MIPs NCs for TC was as low as 10−9 M. [ABSTRACT FROM AUTHOR]