NCL-based mitochondrial-targeting fluorescent probe for the detection of Glutathione in living cells

Harnessing Graphdiyne for Selective Cu2+ Detection: A Promising Tool for Parkinson's Disease Diagnostics and Pathogenesis

Cu2+ accelerates the viral-like propagation of α-synuclein fibrils and plays a key role in the pathogenesis of Parkinson's disease (PD). Therefore, the accurate detection of Cu2+ is essential for the diagnosis of PD and other neurological diseases. The Cu2+ detection process is impeded by substances that have similar electrochemical properties. In this study, graphdiyne (GDY), a new kind of carbon allotrope with strong electron-donating ability, was utilized for the highly selective detection of Cu2+ by taking advantage of its outstanding adsorption capacity for Cu2+. Density functional theory (DFT) calculations show that Cu atoms are adsorbed in the cavity of GDY, and the absorption energy between Cu and C atoms is higher than that of graphene (GR), indicating that the cavity of GDY is favorable for the adsorption of Cu atoms and electrochemical sensing. The GDY-based electrochemical sensor can effectively avoid the interference of amino acids, metal ions and neurotransmitters and has a high sensitivity of 9.77 μA·μM-1·cm-2, with a minimum detectable concentration of 200 nM. During the investigating pathogenesis and therapeutic process of PD with α-synuclein as the diagnostic standard, the concentration of Cu2+ in cells before and after L-DOPA and GSH treatments were examined, and it was found that Cu2+ exhibits high potential as a biomarker for PD. This study not only harnesses the favorable adsorption of the GDY and Cu2+ to improve the specificity of ion detection but also provide clues for deeper understanding of the role of Cu2+ in neurobiology and neurological diseases.

Glutathione detection in water and milk using a new probe DCYP based on benzopyranonitrile

Glutathione (GSH) is a potent antioxidant, fragrance, and anti-browning agent in the field of food chemistry. The accurate GSH evaluation in food and vegetables is critical for instructing the right supplementation of GSH in body. However, most reported GSH fluorescent probes were utilized for the biological imaging. In this study, a new probe DCYP-GSH was developed by coupling of benzopyranonitrile as signal reporter to N-methylpyridine through C = C bond as binding site. Notably, a significant increase in fluorescence intensity and a λmax red-shift of DCYP-GSH in electron spectra were found as a result of the response to GSH. Quantitative detection of GSH in water and milk samples were achieved using probe DCYP-GSH. The development of DCYP-GSH was anticipated to provide an effective toolkit for food safe evaluation.

Mitochondria-targeted ruthenium(II) complexes for photodynamic therapy and GSH detection in living cells

Photodynamic therapy is an emerging tumor therapy that kills tumor cells by activating reactive oxygen species (ROS) produced by photosensitizers. Mitochondria, as an important organelle, are the main generator of cellular ROS. Therefore, the development of photosensitizers capable of targeting mitochondria could significantly enhance the efficacy of photodynamic therapy. In this study, two novel ruthenium(II) complexes, Ru-1 and Ru-2, were designed and synthesized, both of which were functionalized with α,β-unsaturated ketones for sensing of glutathione (GSH). The crystal structures of the two complexes were determined and they exhibited good recognition of GSH by off-on luminescence signals. The complex Ru-2 containing aromatic naphthalene can enter the cells and react with GSH to generate a strong luminescence signal that can be used to monitor intracellular GSH levels through imaging. Ru-2 also has an excellent mitochondrial localization ability with a Pearson's coefficient of 0.95, which demonstrates that it can efficiently target the mitochondria of tumor cells to enhance the effectiveness of photodynamic therapy as a photosensitizer.

A Enhanced Fluorescent Probe for Simultaneous Detection and Discrimination of Hydrogen Bisulfite Anions and Glutathione

Bisulfite (HSO3-) and biological thiols molecules, such as glutathione (GSH), cysteine (Cys), and homocysteine (Hcy), play important roles in organisms. Developing a fluorescent probe that can simultaneously detect and distinguish HSO3- and biological thiols is of great significance. In this study, ethyl(2E,4Z)-5-chloro-2-cyano-5-(7-(diethylamino)-2-oxo-2 H-chromen-3-yl)penta-2,4-dienoate (CCO) as a novel enhanced fluorescence probe was synthesized by integrating coumarin derivatives and ethyl cyanoacetate, which can simultaneous detection and discrimination of hydrogen bisulfite anions and glutathione. The sensing mechanism was elucidated through spectral analysis and some control experiments. In weakly alkaline environments, the probe not only has good selectivity for HSO3- and GSH, but also has a lower detection limits of 0.0179 µM and 0.2034 µM. The probe exhibited fuorescent turn-on for distinguishing with 296 and 28 fold the fluorescent intensity increase at 486 and 505 nm, respectively, through diferent excitation wavelengths. This provides a new method for simultaneous detection and discrimination of HSO3- and biological thiol cell levels and further applications.

New Rhodamine-based sensor for high-sensitivity fluorescence tracking of Cys and simultaneously colorimetric detection of H2S

Sulfhydryl-containing compounds including cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and hydrogen sulfide (H2S) are involved in many physiological processes. The development of single-molecule optical sensor for the distinguish detection of these bio-thiols is a critical and challenging effort. In this work, we designed a one-step synthesis of the Rhodamine-based sensor FR for specific fluorescent response of Cys and simultaneously colorimetric detection of H2S, in which the aldehyde and fluorine groups act as response sites. Sensor FR displays significant fluorescence enhancement at 565 nm toward Cys with high selectivity and low detection limits (49 nM) due to the low background fluorescent signal of the spirocyclic closed-state in Rhodamine structure. Meantime, after treatment of H2S, the color of the sensor changes significantly from colorless to blue-purple, which can be used as a visual colorimetric method to detect H2S. These response mechanisms were systematically characterized by 1H NMR and Mass spectrometry. Finally, sensor FR could be used to monitor exogenous and endogenous of intracellular Cys changes.

Meso-aryltellurium-BODIPY-based fluorescence turn-on probe for selective, sensitive and fast glutathione sensing in HepG2 cells

Glutathione (GSH) as one most abundant thiol, acts as important roles in regulating cellular redox activities, and various diseases are closely related with its abnormal levels. Thus, monitoring intracellular GSH levels is essential for understanding cellular metabolism of many related diseases. In this work, we firstly reported a new fluorescence turn-on sensor, which was capable of selectively, sensitively and rapid sensing GSH over other thiols, especially cysteine and homocysteine in solutions and living cells. A meso-aryltellurium boron dipyrromethene (BODIPY) was firstly designed and synthesized, which showed silenced emission due to an efficient photoinduced electron transfer (PET) process from electron-rich Te to BODIPY, and then upon exposure to GSH, the meso-Te-C bond could be rapidly cleaved by the thiol group of GSH, thus resulting in an obvious fluorescence "turn-on" phenomenon through inhibition of the PET effect. This probe exhibited excellent selectivity and sensitivity towards GSH with a short response time of 2 min, showing a remarkable fluorescence enhancement observed at 541 nm with a large fluorescence quantum yield increase from nearly 0 to 0.73 upon excitation at 500 nm in PBS/CH3CN (9/1, v/v). The detection limit towards GSH was further calculated to be 1.7 nM by the linear fluorescence change at 541 nm in the GSH-concentration ranging from 0 to 4 μM. Furthermore, its sensing mechanism was validated by using mass spectrometry, confirming the rapid cleavage of the Te-C bond by GSH. Finally, cell imaging experiments demonstrated that this probe could successfully detect GSH in living cells, highlighting its potential for rapid and sensitive detection of intracellular GSH level changes. Therefore, a new meso-aryltellurium-BODIPY fluorescence turn-on sensor was firstly developed, which could selectively, sensitively and fast detect cellular GSH over other thiols based on the rapid cleavage of the meso Te-C bond.

Visualization of peroxynitrite/GSH cross-talk in the oxidant-antioxidant balance by a dual-fluorophore and dual-site based mito-specific fluorescent probe

Peroxynitrite (ONOO-) and glutathione (GSH) play mutually regulating roles in the oxidant-antioxidant balance of organisms, which has a profound relationship with people's health and disease. In this study, we designed a two-photon fluorescent probe CD-NA that could simultaneously detect ONOO- and GSH via dual-fluorophore and dual-site properties. CD-NA shows different fluorescence responses to ONOO- (annihilated red fluorescence) and GSH (enhanced green emission) with high specificity and sensitivity. Notably, the response of CD-NA to ONOO- was unaffected by GSH, and the reverse is also true. It allows the ONOO-/GSH cross-talk to be successfully imaged. Given these excellent properties, CD-NA has been favorably employed in detecting ONOO- and GSH in living cells with the ability to target mitochondria. Therefore, CD-NA offers an efficient method for understanding the oxidant-antioxidant balance and interrelated physiological functions of ONOO- and GSH in living systems, and provides a new strategy to sort out the complex relationships and roles of various analytes in complex physiological processes.

Investigating the role of mitochondrial DNA D-loop variants, haplotypes, and copy number in polycystic ovary syndrome: implications for clinical phenotypes in the Chinese population

Background

The presence of genetic variations in mitochondrial DNA (mtDNA) has been associated with a diverse array of diseases. The objective of this study was to examine the correlations between mtDNA D-loop, its haplotypes, and polycystic ovary syndrome (PCOS) in the Chinese population, and the associations between mtDNA D-loop and symptoms of PCOS. The study also sought to determine whether the mtDNA copy number in Chinese patients with PCOS differed from that of individuals in the control group.

Methods

Infertile individuals who only had tubal or male factor treatment were the focus of research by The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). mtDNA haplotypes were categorized using polymorphic D-loop sites. mtDNA D-loop, PCOS features, and mtDNA haplotypes were analyzed using R software to determine the strength of the association between the three. There are certain DNA haplotypes linked to PCOS. Microdroplet digital polymerase chain reaction (PCR) was used to determine the mtDNA copy number in a convenience sample of 168 PCOS patients and 83 controls.

Results

Among the research group, the majority of D-loop mutations were infrequent (frequency< 1%), with only 45 variants displaying a minimum allele frequency (MAF) of 5% or higher. No association was found between polymorphism loci in PCOS patients and body mass index (BMI). Noteworthy, C194T, 1A200G, 523delAC, and C16234T showed positive correlations with elevated LH/FSH levels. Additionally, specific polymorphic loci G207A, 16036GGins, and 16049Gins within the D-loop region of mtDNA potentially exerted a protective role in PCOS development. Conversely, no statistical significance was observed in the expression levels of C16291T and T489C. Chinese women with mtDNA haplotype A15 exhibited a decreased risk of developing PCOS. Moreover, a significant difference in mtDNA copy number was detected, with controls averaging 25.87 (21.84, 34.81), while PCOS patients had a mean of 129.91 (99.38, 168.63).

Conclusion

Certain mtDNA D-loop mutations and haplotypes appear to confer protection against PCOS in Chinese women. In addition, elevated mtDNA copy number may serve as an indicator during early stages of PCOS.

Bright Green-Emissive Carbon Nanodots for Sensing and Intracellular Imaging of Cu2+ and Glutathione

Green-emissive carbon nanodots (CDs) with high quantum yield are prepared. The abundant functional groups on the surfaces of CDs can selectively interact with Cu2+. The formed cupric amine complexes induce significant fluorescence quenching. The "on-off" switching can be further adjusted to the fluorescence "on" mode by the introduction of glutathione (GSH), which hinders the interactions between CDs and Cu2+. Based on the fantastic optical behavior of CDs, highly sensitive detection of Cu2+ and GSH can be achieved. Intracellular imaging of the two targets is also validated.

Early diagnosis of heterotopic ossification with a NIR fluorescent probe by targeting type II collagen

Heterotopic ossification (HO) is a devastating sequela in which the pathologic extracellular matrix of the cartilage and bone forms abnormally in soft tissues following traumatic injuries or orthopaedic surgeries. Early treatment is essential for inhibiting the progression of HO but is currently limited by the absence of sensitive and specific early diagnosis. Herein, this study exploits the enrichment of type II collagen (Col2a1) in the HO cartilage formation stage towards developing a near-infrared (NIR) probe for early HO diagnosis, namely WL-808 by conjugating a Col2a1-binding peptide (WYRGRL) and a cyanine dye (IR-808). WL-808 exhibits high specificity for targeting the cartilage in vitro and in vivo with no apparent cytotoxicity. The NIR signal of WL-808 can be detected in the HO cartilage lesions as early as 1 week after injury when micro-CT cannot show any ectopic bone formation. Moreover, the probe is rarely distributed in the normal knee articular cartilage in vivo via the intravenous administration method. Taken together, WL-808 demonstrates great potential in early HO diagnosis under NIR imaging, facilitating early HO prophylaxis and treatment in the clinic.

Investigation of mitochondrial targeting ability of sydnones and sydnonimines and mitochondria-targeted delivery of celecoxib

Mitochondria are considered to be a promising target in cancer diagnosis and therapeutics. Recently, sydnone and sydnonimine, as mesoionic bioorthogonal reagents, have been used in cell labeling and drug delivery. Here we investigated the mitochondrial targeting ability of sydnones and sydnonimines for the first time. Experimental results show that sydnone and sydnonimine themselves have high mitochondrial distribution. However, the introduction of a phenyl group into the C₄ position of sydnone dramatically decreases the mitochondrial affinity. In addition, we took advantage of mitochondrial targeting ability and click-and-release reaction of sydnonimine to evaluate anticancer activities of in-mitochondria delivery of celecoxib against HeLa and HepG2 cells, indicating that celecoxib-induced cancer cell death may not involve mitochondria-related pathway.

A water-soluble fluorescent probe for monitoring mitochondrial GSH fluctuations during oxidative stress

In this research, we constructed a styrylpyridine derivative-based fluorescent probe MITO-PQDNs to monitor mitochondrial glutathione (GSH). The probe MITO-PQDNs could react rapidly (20 min) with GSH in PBS buffer and exhibited a strong fluorescence signal (586 nm) as well as a significant Stokes shift (200 nm). Moreover, MITO-PQDNs could quantitatively detect GSH with high sensitivity (LOD = 253 nM). Meanwhile, MITO-PQDNs possessed favorable biocompatibility and could detect both endogenous and exogenous GSH in MCF-7 cells. Above all, MITO-PQDNs enabled the detection of fluctuations in mitochondrial GSH concentrations during oxidative stress.

Systematic Screening of Trigger Moieties for Designing Formaldehyde Fluorescent Probes and Application in Live Cell Imaging

Formaldehyde (FA) is involved in multiple physiological regulatory processes and plays a crucial role in memory storage. Meanwhile, FA has a notorious reputation as a toxic compound, and it will cause a variety of diseases if its level is unbalanced in the human body. To date, there have been numerous fluorescent probes for FA imaging reported. Among them, the probes based on the 2-aza-Cope rearrangement have attracted the most attention, and their applications in cell imaging have been greatly expanded. Herein, we screened the various trigger moieties of FA fluorescent probes based on the mechanism of 2-aza-Cope rearrangement. FA-2, in which a fluorophore is connected to a 4-nitrobenzylamine group and an allyl group, demonstrated the highest sensitivity, selectivity, and reaction kinetics. Furthermore, FA-Lyso, derived from FA-2, has been successfully designed and applied to monitor exogenous and endogenous FA fluctuations in lysosomes of living cells.