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The development of molecular theranostic prodrugs for in vivo cancer diagnosis and targeted chemotherapy is urgently required. Enzyme-activated prodrugs display superior selectivity as a result of cancer-specific enzymes which serve as cancer biomarkers. Herein, an aminopeptidase N (APN)activated theranostic prodrug Nile blue-C 6 -amide-p-fluorophenylalanyl-lmelphalanyl (NBFMel) is reported for fluorescence cancer diagnosis and local tumor treatment. NBFMel demonstrates negligible cytotoxicity and very weak fluorescence due to the photoinduced electron transfer (PET) between melphalan and Nile blue fluorophore. After activation caused by APN, the prodrug releases free melphalan that inhibits tumor cell growth. Simultaneously, the reaction blocks the PET process and switches on the fluorescence, which can be used for cancer diagnosis. NBFMel is successfully utilized to report the presence of tumor and for in situ tracking of drug release in tumor-bearing mouse models. Moreover, NBFMel demonstrates efficient tumor inhibition when intravenously injected into mice. Therefore, the APN-activated theranostic prodrug provides a new platform for in vivo cancer diagnosis and targeted anticancer chemotherapy.

Solid polymer electrolytes (SPEs) possess comprehensive advantages such as high flexibility, low interfacial resistance with the electrodes, excellent film-forming ability, and low price, however, their applications in solid-state batteries are mainly hindered by the insufficient ionic conductivity especially below the melting temperatures, etc. To improve the ion conduction capability and other properties, a variety of modification strategies have been exploited. In this review article, we scrutinize the structure characteristics and the ion transfer behaviors of the SPEs (and their composites) and then disclose the ion conduction mechanisms. The ion transport involves the ion hopping and the polymer segmental motion, and the improvement in the ionic conductivity is mainly attributed to the increase of the concentration and mobility of the charge carriers and the construction of fast-ion pathways. Furthermore, the recent advances on the modification strategies of the SPEs to enhance the ion conduction from copolymer structure design to lithium salt exploitation, additive engineering, and electrolyte micromorphology adjustion are summarized. This article intends to give a comprehensive, systemic, and profound understanding of the ion conduction and enhancement mechanisms of the SPEs for their viable applications in solid-state batteries with high safety and energy density.

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