Sensing gastric cancer exosomes with MoS2-based SERS aptasensor.

Exosomes have been widely used in early cancer diagnosis as promising cancer biomarkers due to their abundant tumor-specific molecular information. In this study, we developed a sensitive and straightforward surface-enhanced Raman scattering (SERS) aptasensor to detect exosomes based on gold nanostars-decorated molybdenum disulfide (MoS2) nanocomposites (MoS2-AuNSs). ROX-labeled aptamers (ROX-Apt) were assembled on MoS2-AuNSs surface as recognition probes that specifically bind with transmembrane protein CD63 (a representative surface marker on exosomes). Thus obvious ROX Raman signals were obtained through the synergistic Raman enhancement effect of AuNSs and MoS2 nanosheet. In presence of exosomes, ROX-Apt is preferentially tethered onto exosomes and released from the surface of nanocomposites, resulting in a decrease of the SERS signal. Expectedly, the as-fabricated SERS aptasensor was capable of detecting exosomes in a wide range from 55 to 5.5 × 105 particles µL-1 with a detection limit of 17 particles µL-1. Moreover, the aptasensor exhibited accepted stability and potential clinical applicability.

Prussian Blue Nanoparticle Supported MoS2 Nanocomposites as a Peroxidase-Like Nanozyme for Colorimetric Sensing of Dopamine.

An abnormal level of dopamine (DA) is usually related to neurological disorders, including Parkinson's disease. Herein, cubic-shaped, Prussian blue nanoparticle-supported MoS2 nanocomposites (MoS2-CPBNPs) were prepared as peroxidase-like nanozymes for the label-free, colorimetric detection of DA. As expected, the as-prepared MoS2-CPBNPs nanozymes have outstanding peroxidase-like mimicking activity, which can catalyze 3,3',5,5'-Tetramethylbenzidine (TMB) to generate blue, oxidized TMB in the presence of hydrogen peroxide (H2O2). DA can inhibit the oxidation of TMB, which causes blue solutions to fade and become colorless. According to this phenomenon, the developed colorimetric sensor can qualitatively and quantitatively analyze DA ranging from 0 to 300 µM with a detection limit of 0.09 µM. In addition, the high recovery and low relative standard deviation for practical DA determination suggested that this colorimetric sensor has potential for application in biological biosensing and diagnostic fields.

Molybdenum Disulfide-Based Nanoprobes: Preparation and Sensing Application.

The use of nanoprobes in sensors is a popular way to amplify their analytical performance. Coupled with two-dimensional nanomaterials, nanoprobes have been widely used to construct fluorescence, electrochemical, electrochemiluminescence (ECL), colorimetric, surface enhanced Raman scattering (SERS) and surface plasmon resonance (SPR) sensors for target molecules' detection due to their extraordinary signal amplification effect. The MoS2 nanosheet is an emerging layered nanomaterial with excellent chemical and physical properties, which has been considered as an ideal supporting substrate to design nanoprobes for the construction of sensors. Herein, the development and application of molybdenum disulfide (MoS2)-based nanoprobes is reviewed. First, the preparation principle of MoS2-based nanoprobes was introduced. Second, the sensing application of MoS2-based nanoprobes was summarized. Finally, the prospect and challenge of MoS2-based nanoprobes in future were discussed.

A Highly Sensitive SERS and RRS Coupled Di-Mode Method for CO Detection Using Nanogolds as Catalysts and Bifunctional Probes.

Carbon monoxide (CO) is a commonly poisonous gas. It is important to detect CO in daily life. Herein, a new and sensitive surface enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) coupled di-mode method was developed for CO, based on gold nano-enzyme catalysis and gold nanoprobes. CO can react with HAuCl4 to generate gold nanoparticles (AuNPs) in pH 5.2 HAc-NaAc buffer. The generated AuNPs exhibited SERS activity at 1620 cm-1 in the presence of Vitoria blue B (VBB) molecular probes, and an RRS peak at 290 nm. Based on the AuNP bifunctional probes, the increased SERS and RRS intensities respond linearly with the concentration of CO in the range of 100-1500 ng/mL and 30-5230 ng/mL, respectively. To improve the sensitivity, the produced AuNPs were used as nano-enzyme catalysts for the new indicator reaction of HAuCl4-ethanol (En) to amplify the signal. The sensitive SERS method was coupled with the accurate RRS method to develop a sensitive and accurate SERS/RRS di-mode method for determination of 3.0-413 ng/mL CO, based on the AuNP-HAuCl4-En nanocatalytic reaction and its product of AuNPs as SERS and RRS bifunctional probes.