Great challenges in investigating the release of drug in complex cellular microenvironments necessitate the development of stimuli-responsive drug delivery systems with real-time monitoring capability. In this work, a smart drug nanocarrier based on fluorescence resonance energy transfer (FRET) is fabricated by capping graphene quantum dots (GQDs, the acceptor) onto fluorescent mesoporous silica nanoparticles (FMSNs, the donor) via ATP aptamer for real-time monitoring of ATP-triggered drug release. Under extracellular conditions, the fluorescence of FMSNs remains in the "off" state in the low ATP level which is unable to trigger the release of drug. Once specifically recognized and internalized into the target tumor cells by AS1411 aptamer, in the ATP-rich cytoplasm, the conformation switch of the ATP aptamer causes the shedding of the GQDs from the nanocarriers, leading to the release of the loaded drugs and consequently severe cytotoxicity. Simultaneously, the fluorescence of FMSNs turns "on" along with the dissociation of GQDs, which allows real-time monitoring of the release of drug from the pores. Such a drug delivery system features high specificity of dual-target recognition with AS1411 and ATP aptamer as well as high sensitivity of the FRET-based monitoring strategy. Thus, the proposed multifunctional ATP triggered FRET-nanocarriers will find potential applications for versatile drug-release monitoring, efficient drug transport, and targeted cancer therapeutics.

A simple and effective fluorescence method for the detection of TNT has been developed based on the recognition of amine-capped silicon quantum dots (SiQDs) to TNT.

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Halide perovskite materials have emerged as a new class of revolutionary photovoltaic and optoelectronic nanomaterials. However, the study on electrochemiluminescence (ECL) from halide perovskite nanomaterials is still in its infancy due to their instability, sensitivity, and difficulties in purification and film formation. Here, we propose a scraping coating method for the fabrication of high-quality halide perovskite quantum dot (QD) film on electrode, which shows dense and uniform packing with minimum grain size. When CsPbBr QDs are taken as model materials, highly efficient ECL can be obtained from such perovskite QD film with anhydrous ethyl acetate as both electrolyte and coreactant. The CsPbBr QD film displays intense and stable ECL with ultranarrow emission spectrum bandwidth (24 nm). The CsPbBr QD film shows an extremely high ECL efficiency which is up to 5 times relative to the standard Ru(bpy)/tri-n-propylamine system. This approach is universal and also applies to hybrid organic-inorganic halide perovskite QDs. This work not only extends the properties and applications of halide perovskite materials but also provides a new method for the in-depth study on the structure and properties of these kinds of materials.

Metal‐organic frameworks (MOFs) have attracted considerable attention as promising next‐generation active electrode materials for lithium‐ion batteries (LIBs) or sodium‐ion batteries (SIBs) because of ultrahigh specific surface area, uniformly distributed pores, and tunable structure. However, there are some disadvantages inevitably far from meeting commercial requirements, such as low conductivity, inconvenient electron transmission, and unsatisfactory circulation stability. In this review, a comprehensive summary of MOFs‐based electrode materials is presented and discussed. First, the general Li+/Na+ storage mechanism in MOFs‐based electrode materials, including conversion‐ and insertion‐type reactions, are summarized with details of active inorganic/organic ligands. Second, MOFs as anode materials for LIBs/SIBs are emphasized and improved on the electrochemical performances. Furthermore, very few research literature on MOFs‐based cathode materials is also discussed. Finally, opinions and prospects on the current challenge of MOFs‐based electrode materials are provided for future research directions.

In vivo monitoring of cargo protein delivery is critical for understanding the pharmacological efficacies and mechanisms during cancer therapy, but it still remains a formidable challenge because of the difficulty in observing nonfluorescent proteins at high resolution and sensitivity. Here we report an outer-frame-degradable nanovehicle featuring near-infrared (NIR) dual luminescence for real-time tracking of protein delivery in vivo. Upconversion nanoparticles (UCNPs) and fluorophore-doped degradable macroporous silica (DS) with spectral overlap were coupled to form a core–shell nanostructure as a therapeutic protein nanocarrier, which was eventually enveloped with a hyaluronic acid (HA) shell to prevent protein leakage and for recognizing tumor sites. The DS layer served as both a container to accommodate the therapeutic proteins and a filter to attenuate upconversion luminescence (UCL) of the inner UCNPs. After the nanovehicles selectively accumulated at tumor sites and entered cancer cells, intracellular hyaluronidase (HAase) digested the outermost HA protective shell and initiated the outer frame degradation-induced protein release and UCL restoration of UCNPs in the intracellular environment. Significantly, the biodistribution of the nanovehicles can be traced at the 710 nm NIR fluorescence channel of DS, whereas the protein release can be monitored at the 660 nm NIR fluorescence channel of UCNPs. Real-time tracking of protein delivery and release was achieved in vitro and in vivo by NIR fluorescence imaging. Moreover, in vitro and in vivo studies manifest that the protein cytochrome c-loaded nanovehicles exhibited excellent cancer therapeutic efficacy. This nanoplatform assembled by the outer-frame-degradable nanovehicles featuring NIR dual luminescence not only advances our understanding of where, when, and how therapeutic proteins take effect in vivo but also provides a universal route for visualizing the translocation of other bioactive macromolecules in cancer treatment and intervention.

Monitoring drug release in vitro and in vivo is of paramount importance to accurately locate diseased tissues, avoid inappropriate drug dosage, and improve therapeutic efficiency. In this regard, it is promising to develop strategies for real-time monitoring of drug release inside targeted cells or even in living bodies. Thus far, many multi-functional drug delivery systems constructed by a variety of building blocks, such as organic molecules, polymeric nanoparticles, micelles, and inorganic nanoparticles, have been developed for drug release monitoring. Especially, with the advancements in imaging modalities relating to nanomaterials, there has been an increasing focus on the use of non-invasive imaging techniques for monitoring drug release and drug efficacy in recent years. In this review, we introduce the application of fluorescence imaging, magnetic resonance imaging (MRI), surface-enhanced Raman scattering (SERS), and multi-mode imaging in monitoring drug release, involving a variety of nanomaterials such as organic or inorganic nanoparticles as imaging agents; their design principles are also elaborated. Among these, a special emphasis is placed on fluorescence-based drug release monitoring strategies, followed by a brief overview of MRI, SERS, and multi-mode imaging-based strategies. In the end, the challenges and prospects of drug release monitoring are also discussed.

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