The identification and detection of various types of explosives are essential for human health and environmental monitoring. Array-based sensing approach offers significant advantages in detecting multi-analytes simultaneously, thereby holding great potential in identifying multiple explosives. Here, we report a tri-channel fluorescence array composed of three distinct fluorescence probes based on gold nanoclusters and nicotinamide adenine dinucleotide with well-separated emission colors. Through the specific interactions of explosives with different fluorescent probes and the yielded response patterns, seven explosives can be successfully distinguished with 100% accuracy. In particular, the sensor array exhibits excellent performance in the quantitative analysis of individual explosive and the differentiation of multiple explosive mixtures. To facilitate the field detection towards practical application, the tri-channel fluorescence array was further integrated with polymer hydrogels. The fabricated portable hydrogel-based array sensors can not only visually identify seven different explosives by their distinct fluorescence color change, but also enable quantitative detection based on linear discriminant analysis (LDA) together with a smartphone. This study illustrates the great potential of hydrogel-based fluorescence sensor array as robust sensors for explosives, which also holds significant promise for the development of portable explosive devices towards practical application.

A thorough understanding of antimicrobial mechanism is of great importance for developing novel, efficient antibacterial agents. While cationic nanoparticles, such as metal nanoclusters (NCs), represent an attractive type of antibacterial nanoagents, their interactions with bacteria remains largely un-elucidated. Herein, we report the synthesis of cationic bovine serum albumin-protected AuAgNCs (cBSA-AuAgNCs), which exhibit both near-infrared (NIR) fluorescence properties and significant antimicrobial effects. With E. coli and S. aureus as the representative bacteria, we investigated the antimicrobial process of cBSA-AuAgNCs in real-time based on their intrinsic fluorescence properties via fluorescence imaging. Our results showed that these cBSA-AuAgNCs exert their antimicrobial effects primarily by attaching on the outer membrane of bacteria without obvious internalization, which is significantly different from the antibacterial process of negatively-charged metal NCs. Further mechanistic investigation showed that these cationic NCs will cause serious disruption to the bacterial membrane due to strong electrostatic interactions, which then leads to over accumulation of reactive oxygen species (ROS) that finally causes the bactericidal action. This study demonstrates the great potential of cationic luminescent metal NCs as novel, traceable antimicrobial agents, which also provides new tools for further understanding microbial interactions of nanomedicines.

Heterogeneous materials made of metal-organic frameworks (MOFs) and optically active nanomaterials have attracted intensive interests in recent years due to their distinct physicochemical properties, but controllable fabrication of these materials remains challenging yet. In this work, we report a new strategy to in situ fabricate heterogeneous nanomaterials based on UiO-66-NH₂ and upconversion nanorods (UCNRs) via a hierarchical and dynamic assembly process. Core–satellite structured UiO-66-NH₂@UCNRs have been successfully fabricated, and the formation mechanism was thoroughly investigated by the combined use of scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Our results revealed the involvement of three main stages: supramolecular assembly of UiO-66-NH₂ precursors with UCNRs, nucleation and growth of UiO-66-NH₂ crystal, and dynamic assembly with UCNRs accompanied by Ostwald ripening. Furthermore, based on the hereditary optical and porous features of the heterogeneous nanomaterials, an enhanced multimodal synergistic anticancer platform has been established by integrating near-infrared (NIR)-triggered photodynamic therapy (PDT) and pH-triggered anticancer drug delivery, as confirmed by cellular experiments. The present study provides a new avenue for developing advanced functional heterogeneous nanomaterials via the hierarchical and dynamic assembly strategy.