Photodynamic therapy (PDT), which relies on photosensitizers (PS) and light to generate reactive oxygen species to kill cancer cells or bacteria, has attracted much attention in recent years. PSs with both bright emission and efficient singlet oxygen generation have also been used for image-guided PDT. However, simultaneously achieving effective O generation, long wavelength absorption, and stable near-infrared (NIR) emission with low dark toxicity in a single PS remains challenging. In addition, it is well known that when traditional PSs are made into nanoparticles, they encounter quenched fluorescence and reduced O production. In this contribution, these challenging issues have been successfully addressed through designing the first photostable photosensitizer with aggregation-induced NIR emission and very effective O generation in aggregate state. The yielded nanoparticles show very effective O generation, bright NIR fluorescence centered at 820 nm, excellent photostability, good biocompatibility, and negligible dark in vivo toxicity. Both in vitro and in vivo experiments prove that the nanoparticles are excellent candidates for image-guided photodynamic anticancer therapy.

Organic nanoparticles exhibiting intense FR/NIR chemiluminescence and strong chemiexcited singlet oxygen generation in the presence of H 2 O 2 have been successfully used for selective tumor imaging and therapy. Both tumor chemiluminescent signals and singlet oxygen production can be further enhanced in the presence of an anti-tumor drug, FEITC, which could increase the amount of H 2 O 2 at the tumor site for effective tumor treatment. Our design represents a new strategy for light-source-free image-guided tumor therapy.

Bacterial infection is one of the most serious physiological conditions threatening human health. There is an increasing demand for more effective bacterial diagnosis and treatment through noninvasive theranostic approaches. Herein, a new strategy is reported to achieve in vivo metabolic labeling of bacteria through the use of MIL-100 (Fe) nanoparticles (NPs) as the nanocarrier for precise delivery of 3-azido-d-alanine (d-AzAla). After intravenous injection, MIL-100 (Fe) NPs can accumulate preferentially and degrade rapidly within the high H O inflammatory environment, releasing d-AzAla in the process. d-AzAla is selectively integrated into the cell walls of bacteria, which is confirmed by fluorescence signals from clickable DBCO-Cy5. Ultrasmall photosensitizer NPs with aggregation-induced emission characteristics are subsequently designed to react with the modified bacteria through in vivo click chemistry. Through photodynamic therapy, the amount of bacteria on the infected tissue can be significantly reduced. Overall, this study demonstrates the advantages of metal-organic-framework-assisted bacteria metabolic labeling strategy for precise bacterial detection and therapy guided by fluorescence imaging.

Effective photosensitizers are highly desirable in many applications. Herein, Liu and co-workers demonstrate polymerization-enhanced photosensitization, in which conjugated-polymer-based photosensitizers show much higher efficiency in singlet oxygen ( 1 O 2 ) production than their small-molecule analogs. Based on this concept, conjugated polymer photosensitizer CP1 with an aggregation-induced emission feature is proposed to show highly efficient 1 O 2 generation ability superior to that of its small-molecule analog SM1 and commercial photosensitizer Ce6 in photodynamic therapy, organic waste decomposition, and photocatalytic reactions.

Ferroptosis regulates cell death through reactive oxygen species (ROS)‐associated lipid peroxide accumulation, which is expected to affect the structure and polarity of lipid droplets (LDs), but with no clear evidence. Herein, we report the first example of an LD/nucleus dual‐targeted ratiometric fluorescent probe, CQPP, for monitoring polarity changes in the cellular microenvironment. Due to the donor–acceptor structure of CQPP, it offers ratiometric fluorescence emission and fluorescence lifetime signals that reflect polarity variations. Using nucleus imaging as a reference, CQPP was applied to report the increase in LD polarity and the homogenization of polarity between LDs and cytoplasm in the ferroptosis model. This LD/nucleus dual‐targeted fluorescent probe shows the great potential of using fluorescence imaging to study ferroptosis and ferroptosis‐related diseases.