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Peroxidase (POD)-like nanozymes have been found to act as nanoreactors for the generation of reactive oxygen species (ROS) to resolve drug resistance in the tumor microenvironment (TME). Amplifying cellular oxidative stress is considered to be a drug-free strategy to efficiently induce apoptosis in tumor cells. However, the limited content of intracellular hydrogen peroxide (H2O2) extremely restricts the performance of POD-like nanozymes to amplify cellular oxidative stress. Moreover, additional operational processes combined with exogenous reagents to achieve oxidative stress lead to a dilemma of extra cytotoxicity. Here, an integrated iron-porphyrin-MOF-based nanozyme composite named HA@GOx@PCN-224(Fe) (HGPF) was precisely designed and constructed. Generally, the POD-like nanozyme PCN-224(Fe) was used as a platform to immobilize glucose oxidase (GOx), and further embedded with hyaluronic acid (HA) to enable the targeting ability of tumor cells. When endocytosed by tumor cells, intracellular glucose was oxidized to H2O2 and gluconic acid catalyzed by immobilized GOx of HGPF. Afterwards, inspired by heme analogs, H2O2 was catalyzed by iron-porphyrin active sites of the HGPF nanozyme to generate hydroxyl radicals (˙OH). Under light irradiation, the iron-porphyrin of HGPF acted as a photosensitizer to facilely produce singlet oxygen (1O2). Such a synergistic generation of ROS strikingly amplified oxidative stress and induced severe apoptosis in tumor cells. HGPF was expected to integrate intracellular oxygen sources and overcome the dilemma of limited intracellular H2O2 content. Consequently, HGPF was constructed as an integrated nanoreactor to simultaneously achieve light-enhanced catalytic oxidation cascades, providing a promising strategy for a synergistic amplification of cellular oxidative stress. [ABSTRACT FROM AUTHOR]

Biothiols and SO2 play crucial roles in many physiological and pathological processes. To unravel their complicated interrelationship and cellular cross-talk, it would be highly desirable to develop single-molecule fluorescent probes that can selectively detect biothiols and SO2via different emission channels. Here, a novel chromenylium derivative, BPO-Py-diNO2, based on the rational design of dual recognition sites for biothiols and SO2 selectively and sensitively responded to biothiols with near-infrared fluorescence, and to SO2 with green fluorescence. The emission shift for the two channels was 170 nm. BPO-Py-diNO2 was selectively enriched in lysosomes. It could also be used to evaluate dual-channel imaging of endogenous biothiols and SO2 in living HeLa cells, and it could be used for monitoring the mutual interconversion of biothiols and SO2. [ABSTRACT FROM AUTHOR]

Biothiols and SO 2 play crucial roles in many physiological and pathological processes. To unravel their complicated interrelationship and cellular cross-talk, it would be highly desirable to develop single-molecule fluorescent probes that can selectively detect biothiols and SO 2 via different emission channels. Here, a novel chromenylium derivative, BPO-Py-diNO 2 , based on the rational design of dual recognition sites for biothiols and SO 2 selectively and sensitively responded to biothiols with near-infrared fluorescence, and to SO 2 with green fluorescence. The emission shift for the two channels was 170 nm. BPO-Py-diNO 2 was selectively enriched in lysosomes. It could also be used to evaluate dual-channel imaging of endogenous biothiols and SO 2 in living HeLa cells, and it could be used for monitoring the mutual interconversion of biothiols and SO 2 .