A simple and sensitive fluorescent assay for detecting alkaline phosphatase (ALP) based on the inner filter effect (IFE) has been proven, which is conceptually different from the previously reported ALP fluorescent assays. In this sensing platform, N-doped carbon dots (CDs) with a high quantum yield of 49% were prepared by one-pot synthesis and were directly used as a fluorophore in IFE. p-Nitrophenylphosphate (PNPP) was employed to act as an ALP substrate, and its enzyme catalytic product (p-nitrophenol (PNP)) was capable of functioning as a powerful absorber in IFE to influence the excitation of fluorophore (CDs). When in the presence of ALP, PNPP was transformed into PNP and induced the absorption band transition from 310 to 405 nm, which resulted in the complementary overlap between the absorption of PNP and the excitation of CDs. Because of the competitive absorption, the excitation of CDs was significantly weakened, resulting in the quenching of CDs. The present IFE-based sensing strategy showed a good linear relationship from 0.01 to 25 U/L (R(2) = 0.996) and provided an exciting detection limit of 0.001 U/L (signal-to-noise ratio of 3). The proposed sensing approach was successfully applied to ALP sensing in serum samples, ALP inhibitor investigation and phosphatase cell imaging. The presented IFE-based CDs fluorescence sensing strategy gives new insight on the development of the facile and sensitive optical probe for enzyme activity assay because the surface modification or the linking between the receptor and the fluorophore is no longer required.

The development of a sustainable route to ammonia production is one of the most attractive targets in chemistry. The primary method of ammonia production, Haber-Bosch process, can bring about excessive consumption of fossil fuels and large CO2 emission. In this communication, we develop a VN nanowire array on carbon cloth (VN/CC) as a high-performance catalyst for the nitrogen reduction reaction (NRR) under ambient conditions. Such an electrocatalyst achieves high ammonia yield (2.48 × 10-10 mol-1 s-1 cm-2) and faradaic efficiency (3.58%) at -0.3 V versus RHE in 0.1 M HCl, outperforming most reported results for N2 fixation under ambient conditions, and even comparing favorably with those obtained under high temperatures and/or pressures. This work not only provides us an attractive catalyst material for the NRR in acidic media, but would also open up an exciting new avenue to the rational design and fabrication of transition metal nitrides for the NRR.

Aptamer conjugated porphyrinic metal–organic framework (MOF) achieved target-induced bioimaging and photodynamic therapy.