In this work, one kind of zeolite imidazole frameworks containing bovine serum albumin stabilized Au nanoclusters (AuNCs), beta-galactosidase (beta-Gal) and glucose oxidase (GOx) (AuNCs/beta-Gal/GOx@ZIF-8) were obtained to detect lactose. Compared with other fluorescent nano-materials, AuNCs show distinct advantages as a guest species in ZIF-8, specifically their extremely small size ( < 1 nm), simple synthesis, excellent biocompatibility and high stability. Furthermore, the bovine serum albumin on their surfaces can promote the formation of ZIF-8 coating; thus, AuNCs were co-encapsulated in ZIF-8 with the enzymes together. X-ray diffraction (XRD) analysis indicates the composite possesses the similar crystalline structure with pure ZIF-8. Fluorescence microscope images, Fourier transform infrared spectra and energy dispersive X-ray spectroscopy indicate the presence of AuNCs in the composite. Owing to the high local concentrations of the fluorescent probe and the quenching agent in AuNCs/beta-Gal/GOx@ZIF-8, the quenching rate was enhanced 3.4-fold that of free AuNCs and enzymes in solution.

Catalytic and electrocatalytic applications of supported metal nanoparticles are hindered due to an aggregation of metal nanoparticles and catalytic leaching under harsh operations. Hence, stable and leaching free catalysts with high surface area are extremely desirable but also challenging. Here we report a gold nanoparticles-hosted mesoporous nitrogen doped carbon matrix, which is prepared using bovine serum albumin (BSA) through calcination. BSA plays three roles in this process as a reducing agent, capping agent and carbon precursor, hence the protocol exhibits economic and sustainable. Gold nanoparticles at N-doped BSA carbon (AuNPs@NBSAC)-modified three-electrode strip-based flexible sensor system has been developed, which displayed effective, sensitive and selective for simultaneous detection of uric acid (UA) and dopamine (DA). The AuNPs@NBSAC-modified sensor showed an excellent response toward DA with a linear response throughout the concentration range from 1 to 50 mu M and a detection limit of 0.05 mu M. It also exhibited an excellent response toward UA, with a wide detection range from 5 to 200 mu M as well as a detection limit of 0.1 mu M. The findings suggest that the AuNPs@NBSAC nanohybrid reveals promising applications and can be considered as potential electrode materials for development of electrochemical biosensors.