Reliable Digital Single Molecule Electrochemistry for Ultrasensitive Alkaline Phosphatase Detection.

Single molecule electrochemistry (SME) has gained much progress in fundamental studies, but it is difficult to use in practice due to its less reliability. We have solved the reliability of single molecule electrochemical detection by integration of digital analysis with efficient signal amplification of enzyme-induced metallization (EIM) together with high-throughput parallelism of microelectrode array (MA), establishing a digital single molecule electrochemical detection method (dSMED). Our dSMED has been successfully used for alkaline phosphatase (ALP) detection in the complex sample of liver cancer cells. Compared to direct measurement of the oxidation current of enzyme products, EIM can enhance signals by about 100 times, achieving signal-to-background ratio high enough for single molecule detection. The integration of digital analysis with SME can further decrease the detection limit of ALP to 1 aM relative to original 50 aM, enabling dSMED to be sensitively, specifically and reliably applied in liver cancer cells. The presented dSMED is enormously promising in exploring physical and chemical properties of single molecules, single biomolecular detection, or single-cell analysis.

The special optical properties and application of the heterocyclic compound diethyl 6-anilino-5H-2,3-dithia-5,7-diazacyclopenta(cd)indene-1,4-dicarboxylate.

The heterocyclic compound diethyl 6-anilino-5H-2,3-dithia-5,7-diazacyclopenta(cd)indene-1,4-dicarboxylate (D1) was found to form highly emissive aggregates in polar solvents, and the aggregate emission can be tuned by the simple addition of water to a dimethylsulfoxide solution. A theoretical study based on Density functional theory (DFT) calculations, shows that intermolecular interactions of D1 with solvent may be potential factors in the fluorescence change. In addition, the phenyl ring in D1 plays an important role because of its response to solvent. In the non-aggregated state, deprotonation of the N-H of D1 can proceed easily on the addition of base, and the deprotonated compound might interact with Ag(+), resulting in a significant change in color and fluorescence quenching, which make it a potential chemosensor for the selective detection of trace amounts of Ag(+).

Target-modulated sensitization of upconversion luminescence by NIR-emissive quantum dots: a new strategy to construct upconversion biosensors.

We herein used Ag2Se quantum dots (QDs) as a target-modulated sensitizer for upconversion nanoparticles (UCNPs) and the target thrombin as the sensitizing switch to construct a biosensor, circumventing the limited luminescence resonance energy transfer (LRET) efficiency of UCNPs, with enhanced signal-to-background ratio (SBR) and assay sensitivity.

Controllable synthesis of nanocrystals in droplet reactors.

In recent years, a broad range of nanocrystals have been synthesized in droplet-based microfluidic reactors which provide obvious advantages, such as accurate manipulation, better reproducibility and reliable automation. In this review, we initially introduce general concepts of droplet reactors followed by discussions of their main functional regions including droplet generation, mixing of reactants, reaction controlling, in situ monitoring, and reaction quenching. Subsequently, the enhanced mass and heat transport properties are discussed. Next, we focus on research frontiers including sequential multistep synthesis, intelligent synthesis, reliable scale-up synthesis, and interfacial synthesis. Finally, we end with an outlook on droplet reactors, especially highlighting some aspects such as large-scale production, the integrated process of synthesis and post-synthetic treatments, automated droplet reactors with in situ monitoring and optimizing algorithms, and rapidly developing strategies for interfacial synthesis.