Fluorescent probes for ferroptosis bioimaging: advances, challenges, and prospects.

Ferroptosis is a form of regulatory cell death distinct from caspase-dependent apoptosis and plays an important role in life entities. Since ferroptosis involves a variety of complex regulatory factors, the levels of certain biological species and microenvironments would change during this process. Thus, the investigation of the level fluctuation of key target analytes during ferroptosis is of great significance for disease treatment and drug design. Toward this aim, multiple organic fluorescent probes with simple preparation and non-destructive detection have been developed, and research over the past decade has uncovered a vast array of homeostasis and other physiological characteristics of ferroptosis. However, this significant and cutting-edge topic has not yet been reviewed. In this work, we aim to highlight the latest breakthrough results of fluorescent probes for monitoring various bio-related molecules and microenvironments during ferroptosis at the cellular, tissue and in vivo levels. Accordingly, this tutorial review has been organized according to the target molecules identified by the probes including ionic species, reactive sulfur species, reactive oxygen species, biomacromolecules, microenvironment, and others. In addition to providing new insights into the findings of each fluorescent probe in ferroptosis studies, we also discuss the defects and limitations of the probes developed, and highlight the potential challenges and further prospects in this domain. We anticipate that this review will convey profound implications for designing powerful fluorescent probes to decrypt changes in key molecules and microenvironments during ferroptosis.

Upregulation of Formaldehyde in Parkinson's Disease Found by a Near-Infrared Lysosome-Targeted Fluorescent Probe.

Parkinson's disease (PD) is one of the major neurodegenerative diseases caused by complex pathological processes. As a signal molecule, formaldehyde is closely linked to nervous systems, but the relationship between PD and formaldehyde levels remains largely unclear. We speculated that formaldehyde might be a potential biomarker for PD. To prove it, we constructed the first near-infrared (NIR) lysosome-targeted formaldehyde fluorescent probe (named NIR-Lyso-FA) to explore the relationship between formaldehyde and PD. The novel fluorescent probe achieves formaldehyde detection in vitro and in vivo, thanks to its excellent properties such as NIR emission, large Stokes shift, and fast response to formaldehyde. Crucially, utilizing the novel probe NIR-Lyso-FA, formaldehyde overexpression was discovered for the first time in cellular, zebrafish, and mouse PD models, supporting our guess that formaldehyde can function as a possible biomarker for PD. We anticipate that this finding will offer insightful information for PD pathophysiology, diagnosis, medication development, and treatment.

Discriminating normal and inflammatory mice models by viscosity changes with a two-photon fluorescent probe.

Studies have found that the intracellular viscosity changes have close relationship with many diseases, therefore design and synthesis of fluorescent probe for testing intracellular viscosity is of great significance to the development of clinical. Herein, we developed a new two-photon near infrared probe (HCT) for viscosity imaging to discriminate normal and inflammatory models. Experimental results displayed that HCT has great sensitivity for the detection of viscosity, and based on the excellent performance of its photostability and lower cytotoxicity, HCT was successfully utilized for single-photon/ two-photon fluorescence imaging of the viscosity in living cells. More importantly, we employ HCT to further showcase in living tissues. Additionally, HCT could be used to discriminate between normal and inflamed mice, heralding its practical application in biomedical aspects.

Distinguishing normal and inflammatory models by viscosity changes with sensitively mitochondrial-trackable fluorescent probe.

Biological microenvironment plays a momentous role in the regulation of various vital activities, and its abnormal changes are often closely related to some diseases. Viscosity, as an indispensable part of microenvironment parameters, has always been one of the research hotspots of investigators. Herein, we constructed a new red-emitting fluorescent probe (HVM) to identify the abnormal situation of mitochondria through viscosity changes in the biological microenvironment. Interestingly, HVM has excellent optical properties such as large stokes shift (160 nm), viscosity sensitivity (195-fold), high photostability, and biochemical properties with low cytotoxicity and excellent biocompatibility. For these reasons, the novel probe could successfully be used to identify the normal and inflammatory models via viscosity changes in biological experiments. Therefore, we provided a convenient synthetic route to obtain viscosity sensor HVM with excellent application properties.

Synthesis, molecular docking calculation, fluorescence and bioimaging of mitochondria-targeted ratiometric fluorescent probes for sensing hypochlorite in vivo.

Mitochondria are the main sites for the production of hypochlorite (OCl-). The protein adenine nucleotide translocase (ANT) is located in the inner mitochondria membrane, which is mainly participated in the transportation of ions and metabolites. At the cellular organelle level, overexpression of ANT is associated with enhanced production of OCl-, however, abnormal levels of OCl- cause redox imbalance and loss of function of mitochondria. Herein, a novel mitochondria-targeted ratiometric fluorescent probe Mi-OCl-RP has been developed. Molecular docking calculation suggested a potential molecular target for the probe in the ANT, and the high binding energy (-8.58 kcal mol-1) may explain the high mitochondria selectivity of Mi-OCl-RP. The unique probe exhibits excellent spectral properties including ratiometric fluorescence response signals to OCl- (within 7 s), high selectivity and sensitivity, and a large Stokes shift (278 nm). In addition, the colocalization coefficient confirms that Mi-OCl-RP can effectively target mitochondria. Furthermore, Mi-OCl-RP has low toxicity and good permeability, and was successfully employed in ratiometric imaging of OCl-in vivo, affording a robust molecular tool for investigating the biological functions of OCl- in living systems.

Evaluation of antifatigue and antioxidant activities of the marine microalgae Isochrysis galbana in mice.

The present work aimed to estimate the possible anti-fatigue effect and potential mechanism of Isochrysis galbana (IG) in mice. The anti-fatigue activity of IG (100, 200, and 400 mg/kg) was elucidated by a weight-loaded forced swimming test, and the potential mechanism was explored by determination of fatigue-related biochemical parameters. The results showed that pretreatment with IG significantly extended the exhaustive swimming time and increased the levels of liver glycogen, muscle glycogen and blood glucose in a dose-dependent manner. Besides, the increased levels of alanine aminotransferase, aspartate aminotransferase, blood lactic acid, lactic dehydrogenase, creatine kinase, and blood urea nitrogen by exhausted swimming, were dramatically attenuated by pretreatment with IG. Furthermore, supplementation with IG significantly enhanced the glutathione peroxidase and superoxide dismutase levels, while attenuated the level of malonaldehyde. Taken together, IG possessed appreciable efficacy to alleviate fatigue, and the mechanism might be associated with favorably modulating the process of energy consumption, metabolism, and attenuating oxidative stress injury.

Genetic variations in chromodomain helicase DNA-binding protein 5, gene-environment interactions and risk of sporadic Alzheimer's disease in Chinese population.

CHD5 is an essential factor for neuronal differentiation and neurodegenerative diseases. Here, the targeted next generation sequencing and TaqMan genotyping technologies were carried out for CHD5 gene in a two-staged case-control study in Chinese population. The genetic statistics and gene-environment interactions were analyzed to find certain risk factors of Alzheimer's disease. We found intronic rs11121295 was associated with the risk of Alzheimer's disease at both stages including combined cohorts. This risk effect presented consistently significant associations with the alcoholic subgroups at both all stages in the stratified analysis. The gene-environment interactions further supported the above findings. Our study highlighted the potential role of CHD5 variants in conferring susceptibility to sporadic Alzheimer's disease, especially modified its risk by alcoholic intake.

The single-nucleotide polymorphisms in CHD5 affect the prognosis of patients with hepatocellular carcinoma.

Previous studies showed that the low expressions of chromodomain-helicase-DNA-binding protein 5 (CHD5) were intensively associated with deteriorative biologic and clinical characteristics as well as outcomes in many tumors. The aim of this study is to determine whether CHD5 single nucleotide polymorphisms (SNPs) contribute to the prognosis of hepatocellular carcima (HCC). The SNPs were selected according to their linkage disequilibrium (LD) in the targeted next-generation sequencing (NGS) and then genotyped with TaqMan probers. We revealed a rare haplotype AG in CHD5 (SNPs: rs12564469-rs9434711) was markedly associated with HCC prognosis. The univariate and multivariate regression analyses revealed the patients with worse overall survival time were those with tumor metastasis and haplotype AG, as well as cirrhosis, poor differentiation and IV-TNM stage. Based on the available public databases, we discovered the significant association between haplotype AG and CHD5 mRNA expressions only existed in Chinese. These data proposed that the potentially genetic haplotype might functionally contribute to HCC prognosis and CHD5 mRNA expressions.