Na Li

MOF nanozymes show great promise for biosensing, yet their low catalytic activity hinders practical implementation. Herein, a surface ligand engineering strategy is proposed to boost the hydrolase-like activity of copper-based metal-organic frameworks (CuBPY) for colorimetric immunosensing of alpha-fetoprotein (AFP). 2,9-dimethyl-1,10-phenanthroline (neocuproine, Nc) coordinates with CuBPY, which accelerates substrate hydrolysis and in situ generates a bright-yellow Cu(I)-Nc complex for direct colorimetric readout. This dual-functional Nc enhances CuBPY's catalytic capacity by 1.8-fold. Anti-AFP-loaded CuBPY is prepared via one-step biomineralization, creating a quadruple-functional platform serving as antibody carrier, nanozyme catalyst, signal generator, and amplifier. The immunosensor enables linear AFP detection from 5 to 1000 ng/mL, featuring a 5 ng/mL limit of detection and superior selectivity toward interfering species. Real serum sample analysis demonstrates its accuracy and practicality. This elegant design exploits copper valence-dependent coordination colorimetry, streamlining assay procedures while enhancing catalytic efficiency. It provides new insights for MOF nanozyme enhancement and offers a practical, simplified platform for clinical diagnosis.

The device achieved improved power conversion efficiency via modified ZnO cathode interfacial layer with salicylic acid.

A portable hydrogel fiber-optic sensor for on-site β-galactosidase (β-Gal) detection: β-Gal hydrolysis induces purple Cu( i )-BCA, which quenches SiQD fluorescence in hydrogel via an inner filter effect for point-of-care diagnostics.

Metal-organic frameworks (MOFs) nanozymes represent promising alternatives to natural enzymes, but their catalytic activity and efficiency remain insufficient for practical immunosensing applications. Herein, a neocuproine (Nc)-boosted Cu-MOFs catalytic activity strategy was proposed and applied to develop a rapid and efficient colorimetric immunosensor. Upon Nc assistance, the multi-hydrolase-mimicking catalytic capacities of Cu-MOFs were enhanced by 2.8- to 23.6-fold. Concurrently, the reductant generated during substrate hydrolysis triggered in situ reduction of Cu(II) to Cu(I), yielding a highly colored Cu(I)-Nc chelate for colorimetric analysis. The underlying mechanism of this cascade reaction was systematically explored. As a proof-of-concept, alpha-fetoprotein (AFP) was used to validate the feasibility and practicality of the proposed immunosensor. The analytical performance was satisfactory, with a wide detection range of 5-100 ng/mL, a limit of detection (LOD) of 1.4 ng/mL and an assay time of 5 min. Furthermore, this sensor was successfully applied to the analysis of real serum samples. Notably, Cu-MOFs integrate catalytic substrate hydrolysis, signal amplification, and chromogenic output, enabling simple, rapid sensing. Additionally, the successful implementation of phenanthroline-assisted Cu-MOFs system provides new insights into nanozyme catalysis and clinical immunoassays.

Most fluorescent silicon quantum dots (SiQDs) emit at a single wavelength, which limits their use in ratiometric sensing. Here, we describe the hydrothermal synthesis of dual-emissive SiQDs that showed two distinct peaks at ~ 400 nm and ~ 510 nm under 330 nm excitation. The underlying photoluminescence mechanism was elucidated. Leveraging alkaline phosphatase (ALP)-catalyzed hydrolysis of 4-nitrophenylphosphate disodium salt hexahydrate (PNPP) to 4-nitrophenol (PNP), we developed a ratiometric fluorescence assay for ALP activity that exploits the inner-filter effect among SiQDs, PNPP, and PNP. The sensor delivered a linear signal over the range 1–60 U L^− 1 with a detection limit of 0.79 U L^− 1 and exhibited excellent selectivity against potentially interfering species. Reliable quantification of ALP in animal serum validates the practical utility of the probe. This work expands the toolbox of fluorescent nanomaterials and offers a simple, robust platform for ratiometric biosensing. Graphical Abstract