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

Abstract

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.

Nanoparticle@MoS2 Core–Shell Architecture: Role of the Core Material

“…When a conformal coating is achieved, this architecture also has the unique advantage of maximizing the surface area of the nanocomposite interface, thereby increasing interaction between a functional core and TMD shell . Recently, multiple studies have examined MoS 2 encapsulation of plasmonic nanoparticles (NP), though only complete encapsulation of Au has been definitively demonstrated through advanced microscopy. − These Au@MoS 2 structures have demonstrated attractive performance in a variety of applications including photodetectors, surface enhanced Raman spectroscopy (SERS), and bioimaging . By varying the nature of the nanoparticle core material as well as the type and characteristics of the shell using this geometry, there are abundant opportunities to explore and engineer potentially useful properties.…”

MoS2-Based Substrates for Surface-Enhanced Raman Scattering: Fundamentals, Progress and Perspective

“…The spontaneous reduction method refers to the initiative reduction reaction between the prepared MoS 2 film and the precursor solution of metal nanoparticles such as HAuCl 4 solution (the precursor of gold NPs), to obtain directly the metal/MoS 2 composite substrate. This spontaneous reduction can occur at room temperature or more uniformly and rapidly through auxiliary means such as heating [50,64].…”

“…For the tracking detection aspect, Singha and coworkers [63] used Au NPs/MoS 2 nanoflower hybrid as a SERS substrate, which used Rh6G as a probe molecule with detection limits as low as 10 −12 M. This SERS biosensor detected free bilirubin under the interference of key interfering factors such as glucose, cholesterol and phosphate in human serum, showing good selectivity and reliability, as well as potential for clinical diagnosis. For medical imaging, Fei et al [64] fabricated gold nanoparticles@MoS 2 quantum dots (Au NPs@MoS 2 QDs) core-shell nanocomposite. The pinhole-free, chemically inert and ultrathin MoS 2 QDs shell protected the Au core from the chemical environment and probe molecules.…”

Molybdenum Disulfide-Based Nanoprobes: Preparation and Sensing Application

“…More interestingly, a MoS 2 -based SERS nanoprobe is also a powerful tool for label-free SERS imaging. For example, Fei et al offered an example of a MoS 2 -based nanoprobe for SERS imaging in living 4T1 cells [ 66 ]. Experimental results suggested that a MoS 2 -based nanoprobe may be the promising alternative because of its intrinsic vibrational bands in the Raman-silence region of cells.…”