3,4-Dinitrobenzamide Functionalized CdTe/ZnTe Quantum Dots as a Nanoprobe for Imaging Glutathione S-Transferase in Living Cells

Optimized Fluorescent Probe for Specific Imaging of Glutathione S-Transferases in Living Cells and Mice

GSTP1 has been considered to be a marker for malignancy in many tissues. However, the existing GST fluorescent probes are unfavorable for in vivo imaging because of the limited emission wavelength or insufficient fluorescence enhancement (six-fold). The limited fluorescence enhancement of GST fluorescent probes is mainly ascribed to the high background signals resulting from the spontaneous reaction between GSH and the probes. In this work, a highly specific GST probe with NIR emission has been successfully developed through optimization of the essential unit of the probe to repress the spontaneous reaction. The novel GST probe exhibits over 100-fold fluorescence enhancement upon incubation with GSTP1/GSH and high selectivity over other potential interference. In addition, the probe has been proved to be capable of tracking endogenous GST in A549 cells. Finally, the in vivo imaging results demonstrate that the probe can be used for effective imaging of endogenous GST activity in subcutaneous tumor mouse with high contrast.

GdPO4-Based Nanoprobe for Bioimaging and Selective Recognition of Dipicolinic Acid and Cysteine by a Sensing Ensemble Approach

Multiple functions incorporated in one single-component nanoplatform pave the way for important biomedicine applications. Herein, a multifunctional terbium-doped gadolinium orthophosphate (GdPO₄:Tb-EDTA) nanoplatform was prepared through a simple, ecofriendly, one-step hydrothermal method. Results showed that dipicolinic acid (DPA), the biomarker of bacterial spores, significantly increased the fluorescence intensity of this nanoplatform and conferred it with rapid response and excellent selectivity. Subsequently, the fluorescence of the ensemble GdPO₄:Tb-EDTA-DPA can be remarkably quenched by Cu²⁺, which led to a rewritable nanosensor used in the detection of cysteine (Cys) with excellent sensitivity. In addition, GdPO₄:Tb-EDTA can also be a potential T₁-weighted magnetic resonance imaging (MRI) contrast agent, which indicated a satisfactory in vitro MRI with r₁ relaxivity values of 13.9 mM^-1 s^-1 and in vivo MRI through intravenous administration on a rat model. Overall, the proposed assay may have great theoretical and practical significance for designing multifunctional biomaterials.

Fluorescence detection of glutathione S-transferases in a low GSH level environment

Glutathione S-transferases (GSTs) play crucial roles in the detoxification process and the development of drug-resistance and are proved to be important markers for various tumors.

Near-infrared fluorescent probes for the detection of glutathione and their application in the fluorescence imaging of living cells and tumor-bearing mice

Two new cyanine-based fluorescent probes 1 and 2 have been developed. Probe 1 bears two cyanine units in a single molecule, and probe 2 contains a bis(trifluoromethyl)benzenethiol moiety. Both are non-fluorescent. The addition of intracellular glutathione (GSH) significantly enhanced the NIR fluorescence of the two probes. Both probes were used to image varying amounts of GSH in living cells. In tumor bearing mice, the in vivo fluorescence intensity of both probes was higher in tumors, where GSH is overexpressed, than in normal tissues. These results suggest that these new fluorogenic probes have potential for GSH-targeting diagnostic imaging.