Growth of AgI semiconductors on tailored 3D porous Ti3C2 MXene/graphene oxide aerogel to develop sensitive and selective "signal-on" photoelectrochemical sensor for H2S determination.

Long term exposure to hydrogen sulfide (H2S) even in low concentration poses a serious threat to human health and the ecosystem, pointing to the significance for its effective supervision. In this study, we report a sensitive and selective "signal-on" photoelectrochemical (PEC) sensor for the determination of toxic H2S in aqueous solution by in situ growth of AgI semiconductors on tailored three-dimensional (3D) porous Ti3C2 MXene/graphene oxide aerogel (MGA). Our research demonstrated that the resultant MGA with the starting feeding mass ratio of MXene and graphene oxide (GO) of 1:8 (MGA1:8) possessed the most excellent PEC performance after the growth of AgI semiconductors than their monomers (Ti3C2 MXene and GO) and the MGAs with other starting feeding mass ratio. Such designed PEC sensor based on MGA1:8/AgI heterojunction showed dramatically strengthened PEC responses with increasing concentrations of S2-. Correspondingly, a wide linear range of 5 nM-200 µM, a low limit of detection of 1.54 nM (S/N = 3), and exclusively unique selectivity have been achieved. Our research illustrates that the PEC sensor designed with tailored MGA constitutes is an effective pathway to enhance the overall sensing performance, which will envision to boost more efforts for advanced 3D porous aerogel using in PEC sensors.

An upgraded 2D nanosheet-based FRET biosensor: insights into avoiding background and eliminating effects of background fluctuations.

We demonstrated a new class of 2D nanosheet-based FRET biosensor utilizing vertically oriented MoS2 nanosheets on a magnetic nanocarrier. Compared with the non-separated biosensor under identical conditions, this upgraded one can avoid the background signal of the system and eliminate the effects of background fluctuations, which produces more excellent detection methods.

Controlling the ligands of CdZnTe quantum dots to design a super simple ratiometric fluorescence nanosensor for silver ion detection.

A super simple ratiometric fluorescence nanosensor has been fabricated by controlling the ligands of CdZnTe quantum dots (QDs), allowing the sensitive and visual detection of silver ions (Ag+). The green-emitting L-cysteine-protected CdZnTe QDs (Lcys-CdZnTe QDs) had a specific response to Ag+ and were used as the reporting probe, while the red-emitting N-acetyl-L-cysteine-protected CdZnTe QDs (NAC-CdZnTe QDs) showed no obvious response to all tested metal ions and were selected as the reference probe. Simply mixing them without any encapsulated synthesis ultimately produced a time-saving, low-cost detection method, allowing the sensitive and visual detection of Ag+ in samples. The proposed nanosensor exhibited a linear range of 0.5-4.0 µM along with a detection limit of 0.17 µM, and has been successfully applied in real tap water and lake water samples. This nanosensor also showed obvious color changes in the detection process and has potential in visual semi-quantitative detection. Our approach may provide a general and feasible strategy for designing ratiometric fluorescence nanosensors, which will attract a wide range of interest in sensing-related fields.