Silver Nanoclusters Encapsulated into Metal–Organic Frameworks with Enhanced Fluorescence and Specific Ion Accumulation toward the Microdot Array-Based Fluorimetric Analysis of Copper in Blood

Silver nanoclusters (AgNCs) were first coated with bovine serum albumin (BSA) and then encapsulated into porous metal–organic frameworks of ZIF-8 by the protein-mediated biomineralization process. Unexpectedly, the fluorescence intensities of the yielded AgNCs-BSA@ZIF-8 nanocomposites were discovered to be continuously enhanced during each of the BSA coating and ZIF-8 encapsulation steps. Compared to common AgNCs, greatly improved photostability and storage stability of AgNCs could also be expected. More importantly, having benefited from the ZIF-8 shells, the prepared nanocomposites could possess the specific accumulation and sensitive response to Cu2+ ions, resulting in the rational quenching of their fluorescence intensities. Moreover, AgNCs-BSA@ZIF-8 nanocomposites were coated onto the hydrophobic arraying slides toward a microdots array-based fluorimetric method for the fast and sensitive evaluation of Cu2+ ions. It was discovered that the developed fluorimetric strategy could ensure the high-throughput analysis of Cu2+ ions in wide pH range, and especially some harsh and high-salt media. It can allow for the detection of Cu2+ ions in blood with the concentrations ranging from 4.0 × 10–4 to 160 μM, thus serving as a new copper detection candidate to be widely applied in clinical test, food safety, and environmental monitoring fields.