Synthesis of Au NP@MoS₂ Quantum Dots Core@Shell Nanocomposites for SERS Bio-Analysis and Label-Free Bio-Imaging.

In this work, we report a facile method using MoS₂ quantum dots (QDs) as reducers to directly react with HAuCl₄ for the synthesis of Au nanoparticle@MoS₂ quantum dots (Au NP@MoS₂ QDs) core@shell nanocomposites with an ultrathin shell of ca. 1 nm. The prepared Au NP@MoS₂ QDs reveal high surface enhanced Raman scattering (SERS) performance regarding sensitivity as well as the satisfactory SERS reproducibility and stability. The limit of detection of the hybrids for crystal violet can reach 0.5 nM with a reasonable linear response range from 0.5 μM to 0.5 nM (R² ≈ 0.974). Furthermore, the near-infrared SERS detection based on Au NP@MoS₂ QDs in living cells is achieved with distinct Raman signals which are clearly assigned to the various cellular components. Meanwhile, the distinguishable SERS images are acquired from the 4T1 cells with the incubation of Au NP@MoS₂ QDs. Consequently, the straightforward strategy of using Au NP@MoS₂ QDs exhibits great potential as a superior SERS substrate for chemical and biological detection as well as bio-imaging.