Multifunctional MoS2@AuNSs nanoflakes as SERS and photothermal tags for single-cell bacterial detection and in-situ inactivation

Sensitive detection and in-situ elimination of pathogenic bacteria are important to confront the bacterial infections and antimicrobial resistance threat to public health. In this research, we developed a "two-in-one" MoS2@AuNSs(nanostars) nanoflake as surface-enhanced Raman scattering (SERS) and photothermal tags for sensitively detection and in-situ inactivation of bacteria and biofilm. MoS2@AuNSs nanoflakes possess excellent SERS activity and abundant antibody junction sites for specifically bacteria labelling. Combining with bifunctional Fe3O4@Au as magnetic capture and Raman internal standard (IS) substrate, S. aureus can be separated from complex bio-samples and detected with a detection limit of 1 cell/mL, the variable coefficient of this SERS assay can be decreased to 1.57%, which was more sensitive and stable than the common sandwiched magnetic SERS biosensors. Moreover, MoS2@AuNSs nanoflakes can provide a remarkable photothermal conversion efficiency (43.41%), after treated by 808 nm laser, 100% of free S. aureus and 99% of biofilms can be inactivation. This work demonstrates the potential of MoS2@AuNSs nanoflakes in SERS sensing and photothermal therapy for the first time. By using this strategy, single-cell level in-situ diagnosis and eliminating of pathogenic bacteria in various samples can be realized easily.