A facile one-step microwave-assisted approach for the preparation of strong fluorescent carbon nitride quantum dots (g-CNQDs) by using guanidine hydrochloride and EDTA as the precursors was developed. Strong chemiluminescence (CL) emission was observed when NaClO was injected into the prepared g-CNQDs, and a novel CL system for direct detection of free chlorine was established. Free residual chlorine in water was sensitively detected with a detection limit of 0.01 μM and had a very wide detection range of 0.02 to 10 μM. On the basis of CL spectral, UV-visible absorption spectral, and electron spin resonance (ESR) spectral studies, as well as investigations on the effects of various free radical scavengers, a possible CL mechanism was proposed. It was suggested that the radiative recombination of oxidant-injected holes and electrons in the g-CNQDs accounted for the CL emission. Meanwhile, (1)O2 on the surface of g-CNQDs, generated from some reactive oxygen species in the g-CNQDs-NaClO system, could transfer energy to g-CNQDs and thus further enhance the CL emission. The CL system is highly sensitive and differentiable, opening a new field for the development of novel CL-emitting species, but also expanding the conventional optical utilizations of g-CNQDs.

This study aims to investigate the significance of erythropoietin-producing hepatocellular (Eph)A2 expression and the mechanism by which EphA2 is involved in the epithelial-mensenchymal transition (EMT) of gastric cancer cells. EphA2 expression levels were upregulated and positively correlated with metastasis and EMT markers in human gastric cancer specimens. Modulation of EphA2 expression levels had distinct effects on cell proliferation, cell cycle, migration, invasion and morphology in the gastric cancer cell lines SGC7901 and AGS in vitro and in vivo. Overexpression of EphA2 resulted in the upregulation of the EMT molecular markers N-cadherin and Snail, as well as the Wnt/β-catenin targets TCF4, Cyclin-D1 and c-Myc, while silencing EphA2 using short hairpin RNA had the opposite effect. Furthermore, inhibition of the Wnt/β-catenin pathway by XAV939 negated the effect of EphA2 overexpression, whereas activation of the Wnt/β-catenin pathway by LiCl impaired the effect of the EphA2 knockdown on EMT. These observations demonstrate that EphA2 upregulation is a common event in gastric cancer specimens that is closely correlated with cancer metastasis and that EphA2 promotes EMT of gastric cancer cells through activation of Wnt/β-catenin signaling.

Herein, we present a novel strategy based on a "turn-on" persistent luminescence imaging chemical system of graphitic carbon nitride for detecting biothiols in biological fluids. Graphitic carbon nitride (g-C3N4) as persistent luminescence probe is fabricated via a new procedure based on pyrolysis of guanidine hydrochloride under ambient atmospheric conditions. The prepared g-C3N4 nanosheets give intensively long-persistent luminescence that can avoid interference from biological media such as tissue autofluorescence and scattering light. The original persistent luminescence of g-C3N4 turns off due to the adsorption of silver ion (Ag(+)) onto g-C3N4 materials with an electron transfer process. The presence of biothiols induces the onset of persistent luminescence emission by interrupting the quenching interaction, thereby turning on the imaging probe. The approach exhibits high specificity and high sensitivity to biothiols with low detection limit for cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) with 6.4, 8.1, and 9.6 nM, respectively. It is also successfully applied for imaging detection of biothiols in human urine, plasma, and cell lysates, demonstrating its great value of practical application in biological systems.

A protocol for the photooxidative activation of α-silylamines and α-amino acids for desilylative and decarboxylative additions, allylations and heteroarylations in the presence of graphitic carbon nitride (g-C 3 N 4) was developed. The procedure has broad scope and provides the desired products in high yields. The heterogeneous nature of the g-C 3 N 4 catalytic system enables easy recovery and recycling as well as the use in multiple runs without loss of activity. The photoredox catalyzed reactions can also be conducted in continuous photo flow fashion and scaled up to gram-scale. Thus, the stable and readily available polymeric g-C 3 N 4 provides an alternative to homogeneous photosensitizers for the generation of valuable radical intermediates for applications in synthesis and catalysis.