Golgi apparatus-targeting fluorescent probe for the imaging of superoxide anion (O2•-) in living cells during ferroptosis

Red-emitting aggregation-induced emission fluorescent probe for monitoring fluctuation of HClO in mitochondria during ferroptosis

BACKGROUND

Ferroptosis is an iron-dependent programmed cell death pathway driven by lipid peroxidation that involves various inflammation-related diseases and even cancer, which is often accompanied by the accumulation of mitochondrial ROS. HClO, as one of the vital ROS in organisms, is mainly derived from the mitochondria of cells. And abnormal levels of HClO can disrupt redox homeostasis in cells and lead to various diseases. Importantly, intracellular HClO levels are also associated with ferroptosis. Therefore, it is very important to study the fluctuation of intracellular HClO level during ferroptosis.

RESULTS

Herein, a HClO fluorescent probe TPA-ClO was synthesized using triphenylamine fluorophore and benzothiadiazole structure. Notably, TPA-ClO exhibited the advantages of NIR fluorescence emission, good AIE properties and large Stokes shift, and which could selectively detect HClO with a detection limit of 150.0 nM. TPA-ClO could be well targeted in mitochondria and had been successfully applied to monitor exogenous and endogenous HClO in MCF7 cells. Moreover, the imaging experiment of TPA-ClO indicated that erastin- and RSL3-induced ferroptosis in MCF7 cells led to increased levels of mitochondrial HClO and that MCF7 cells showed high ferroptosis sensitivity to RSL3.

SIGNIFICANCE

TPA-ClO exhibited high selectivity to HClO over other potential interfering substances, and could be employed to monitor HClO level fluctuations in MCF7 cells. More importantly, TPA-ClO could be an effective tool to monitor the fluctuations of HClO level in mitochondria during ferroptosis as well as for investigating various diseases associated with ferroptosis for future research.

Advancements in Small Molecule Fluorescent Probes for Superoxide Anion Detection: A Review

Superoxide anion (O2•-), a significant reactive oxygen species (ROS) within biological systems, plays a widespread role in cellular function regulation and is closely linked to the onset and progression of numerous diseases. To unveil the pathological implications of O2•- in these diseases, the development of effective monitoring techniques within biological systems is imperative. Small molecule fluorescent probes have garnered considerable attention due to their advantages: simplicity in operation, heightened sensitivity, exceptional selectivity, and direct applicability in monitoring living cells, tissues, and animals. In the past few years, few reports have focused on small molecule fluorescence probes for the detection of O2•-. In this small review, we systematically summarize the design and application of O2•- responsive small molecule fluorescent probes. In addition, we present the limitations of the current detection of O2•- and suggest the construction of new fluorescent imaging probes to indicate O2•- in living cells and in vivo.

A superoxide anion responsive and self-reporting fluorescent H2S donor for the treatment of diabetic wound

Superoxide anion (O2•-) not only serves as a critical precursor for numerous damaging reactive oxygen species (ROS), but also is implicated in a variety of diseases, including cancer, cardiovascular disorders, and diabetes. Consequently, reducing the levels of superoxide anions and alleviating oxidative stress are of paramount importance. Conversely, hydrogen sulfide (H2S), recognized as a significant biological signaling molecule, plays vital roles in protecting mammalian cells from oxidative damage and promoting tissue regeneration. In this study, we reported a novel superoxide anion-responsive H2S donor (HSD-SO-B) designed to scavenge O2•- and produce H2S concurrently. This H2S donor exhibits several advantages: (1) rapid response to superoxide anions (O2•-) with remarkable selectivity over competing species (2) generating H2S while scavenging superoxide anions (3) producing ratiometric fluorescence for both visualization and quantification of H2S release. Moreover, this O2•--responsive, self-immolative fluorescent H2S donor has shown significant therapeutic and reparative effects on the diabetic wound model in mice.

Rutin attenuates zearalenone-induced ferroptosis of endometrial stromal cells in piglets through the p53 signaling pathway

Zearalenone (ZEA) is an environmentally widespread mycotoxin capable of posing a serious threat to food safety and public health, and porcine endometrial stromal cells (ESCs) are particularly sensitive to the toxic effects of ZEA. We hypothesized that Rutin, a flavonoid antioxidant, could significantly alleviate ZEA-induced ferroptosis through the p53 signaling pathway. In this study, we used porcine ESCs as a research model. When porcine ESCs were co-cultured with the addition of Rutin and ZEA following p53 gene silencing via siRNA transfection, Rutin significantly mitigated ZEA-induced mitochondrial damage, oxidative stress, and Fe2 + content through the p53 pathway. Additionally Rutin lowered the expression of p53, ALOX12, and ACSL4 while significantly improving cytokinesis, antioxidant enzyme activity, and SLC7A11, GPX4, Nrf2, FTH1, thereby inhibiting cellular ferroptosis. These findings suggested a novel programmed death mechanism for alleviating the cytotoxic effects of ZEA, involving the knockdown of p53.

NIR-excited imaging of drug-induced liver injury using a superoxide-activated ratiometric upconversion luminescence nanoprobe

Drug-induced liver injury (DILI) poses a significant risk to human health. Increasing evidence indicates that the superoxide anion (O2•-), as the precursor of the other reactive oxygen species, is key in the pathological processes associated with DILI. Nonetheless, understanding of the mechanisms of DILI is difficult due to the lack of an imaging tool for monitoring the fluctuation of O2•- levels during the progression of DILI. Herein, we developed an upconversion nanoprobe (Rbh-UCNs) for in vivo ratiometric tracking of endogenous O2•- in DILI. In this design, the addition of O2•- triggers the luminescent resonance energy transfer between Rbh and UCNs, which significantly enhances absorption centered at 534 nm and translates into a distinct decrease of the UCL emission at 543 nm, while the UCL emission peak at 654 nm and 800 nm are not significantly affected, offering a ratiometric UCL signal for the quantitative detection of O2•-. In addition, Rbh-UCNs could effectively visualize endogenous O2•- in living cells, zebrafish, and liver tissues upon stimulation with PMA or cisplatin. More importantly, tissue imaging of the liver region of mice revealed that the fluctuation of O2•- levels is associated with DILI and the protective effect of L-carnitine against DILI. Altogether, this study provides an available method for a deeper comprehension of the mechanisms underlying DILI and accelerating the development process of hepatoprotective medicines.

Progress and limitations in reactive oxygen species quantitation

Reactive oxygen species (ROS) are a set of oxygen- and nitrogen-containing radicals. They are produced from a wide range of sources. In biological contexts, cellular stress leads to an overproduction of ROS, which can lead to genetic damage and disease development. In industry, ROS are often productively used for water purification or for analyzing the possible toxicity of an industrial process. Because of their ubiquity, detection of ROS has been an analytical goal across a range of fields. To understand complicated systems and origins of ROS production, it is necessary to move from qualitative detection to quantitation. Analytical techniques that combine quantitation, high spatial and temporal resolution, and good specificity represent detection methods that can fill critical gaps in ROS research. Herein, we discuss the continued progress and limitations of fluorescence, electrochemical, and electron paramagnetic resonance detection of ROS over the last ten years, giving suggestions for the future of the field.

A hemicyanine-modified upconversion nanoprobe for NIR-excited evaluating superoxide signaling in drug-induced liver injury

BACKGROUND

Drug-induced liver injury (DILI) is the most important standard for the entrance of clinical drugs into the pharmaceutical market. The elevation of superoxide anion (O2•-) during drug metabolism can mediate apoptosis of hepatocytes and further generation of liver damage. Therefore, developing an effective imaging method for evaluating O2•- levels during DILI is of great importance. However, current reported O2•- fluorescent probes either use short excitation wavelengths or a single intensity detection system, limiting the accurate quantification of O2•- in deep tissue in vivo.

RESULTS

We developed a NIR-excited ratiometric nanoprobe (CyD-UCNPs) by assembly of O2•--sensitive hemicyanine dyes (CyD) on the surface of Tm/Er-codoped upconversion nanoparticles (UCNPs) with the assistance of α-cyclodextrin, which exhibited a robust "turn-on" ratiometric sensing signal. In vitro experiments indicated that CyD-UCNPs respond well to O2•- with high selectivity. Furthermore, by taking advantage of the outstanding optical properties produced by the luminescent resonance energy transfer between the UCNPs and CyD upon the excitation of 980 nm, the ratiometric upconversion luminescence signal of CyD-UCNPs was successfully utilized to monitor the fluctuation of O2•- levels under phorbol-12-myristate-13-acetate (PMA)/cisplatin-induced oxidative stress in living cells, liver tissues, and zebrafish. More importantly, endogenous change in O2•- levels in the liver sites of mice during DILI and its prevention with L-carnitine was visualized using CyD-UCNPs.

SIGNIFICANCE

This study provides a ratiometric NIR-excited imaging strategy for investigating the correlation between O2•- levels and DILI and its prevention, which is significant for early diagnosis of DILI and preclinical screening of anti-hepatotoxic drugs in vivo.