Controllable and sufficient concentrations of therapeutic agents in gene therapy are critical to achieve satisfactory outcomes. Herein, a Zn2+/Cu2+ bimetallic nano metal-organic framework loaded with rolling circle amplification (RCA) substrates (termed PZCT) was established for precise and efficient DNAzyme-based gene and chemo-dynamic combined therapy. The activation of PZCT is bioorthogonally controlled by tumor-specific miR-21, which generates numerous DNAzyme for silencing EGR-1 mRNA with the assistance of Zn2+ from PZCT. Simultaneously, the doped copper ions on PZCT exert chemo-dynamic therapy (CDT) by reducing glutathione (GSH) and converting endogenous hydrogen peroxide (H2O2) into hydroxyl radical (OH). These combination therapies exhibited remarkable tumor elimination effects in vivo and promised excellent tumor specificity via a bioorthogonal strategy. The proposed nanoplatform offers new prospects for precise cancer therapeutics by overcoming low transfection efficiency and off-target toxicity in DNAzyme-based approaches.

A coumarin-based dual responsive fluorescent probe with a simple structure was developed for the detection of Cys and HSO3 -. Under simulated physiological conditions, Cou-F displayed an on-off fluorescence response to Cys at 521 nm and an off-on fluorescence response to HSO3 - at 500 nm. Furthermore, Cou-F had the advantages of high sensitivity, strong specificity and rapid response. The detection limits of Cou-F toward Cys and HSO3 - were 0.54 μM and 0.65 μM, respectively. Cou-F enabled high selective responses to Cys and HSO3 - over other biologically related species. The response times of Cou-F toward Cys and HSO3 - were 80 s and 100 s. The fluorescence imaging of Cys and HSO3 - was achieved in living RAW246.7 cells.

The homeostatic disorder of intracellular Zn2+ pool is closely associated with severe diseases. It has been reported that the high level of free Zn2+ during ischemia/reperfusion (I/R) process can result in oxidative stress damage on nerve cells. Given that nitrosyl (HNO) can aggravate the nerve injury during cerebral I/R process, we assume that there may exist a mutual regulation between Zn2+ and HNO under certain physiological conditions. To reveal this potential small-signaling-molecule crosstalk, we synthesized two-photon fluorescent probes CHP-H and CHP-CH3 to monitor intracellular Zn2+ in cell and mice hippocampus I/R models. The probes consist of two moieties: coumarin derivative as the two-photon fluorescence transducer, 2-hydrazino pyridine as the fluorescence modulator and Zn2+ chelator. Both probes exhibit excellent analytical properties for Zn2+ detection in simulated physiological systems. Utilizing CHP-H and an HNO probe Cyto-JN, we perform fluorescent imaging of cell I/R models. The results confirm that HNO can stimulate Zn2+ release from labile Zn2+ pool, whereas, the increase of intracellular Zn2+ cannot upregulate the level of HNO. Combining with the deep tissue imaging of mice hippocampus tissues, our probes may provide potential approaches for the medical diagnostic assessment of HNO regulation effect on Zn2+ release in clinical cerebral I/R-related diseases.

We establish a near-infrared two-photon fluorescent probe for the detection of CE2 with high selectivity and sensitivity. This probe exhibits low cytotoxicity and superior tissue penetration ability for evaluating the real-time activity of CE2 in living cells, in cancer tissues, and in a colon carcinoma mice model.

As the most abundant nonprotein biothiol in living cells, glutathione (GSH) prevents cellular components from oxidative damage and maintains the intracellular redox homeostasis. For further exploring whether GSH can be employed as a bioindicator to discriminate tumor lesion at a cellular level, the highly selective detection and accurate quantification of GSH under pathological conditions are critical. Herein, we design a coumarin derivative-based two-photon fluorescent probe Cou-Br for the detection of GSH in living cells, mice models, and clinical specimens. The prepared probe is capable of sensitively and selectively detecting GSH in complex biological systems. Cou-Br displays a good linear relationship in response to GSH and a low limit of detection. With the fluorescence signal positively associated with intracellular GSH levels, the probe enables real-time imaging of GSH in various cell lines. Under the condition of CS2 stimulation, Cou-Br can rapidly respond to the fluctuation of intracellular GSH induced by oxidative damage. Furthermore, the in situ and in vivo bioimaging performances of Cou-Br are demonstrated. Typically, relying on the different cellular concentrations of GSH, the probe is successfully employed to identify the human laryngeal cancer lesion with outstanding capabilities of deep tissue imaging and tumor margin recognition. We assume that the abnormal expression level of GSH may be utilized as a potential bioindicator to discriminate tumor tissues from the surrounding disease-free tissues. To conclude, the proposed probe Cou-Br may potentially serve as a powerful chemical tool for the surgical navigation of cancer in clinic.