Janus-Faced Fluorescence Imaging Agent for Malondialdehyde and Formaldehyde in Brains

A highly sensitive Golgi-targeted fluorescent probe for the simultaneous detection of malondialdehyde and formaldehyde in living systems and foods

Malondialdehyde (MDA) and formaldehyde (FA) are highly active carbonyl substances widely present in both biological and abiotic systems. The detection of MDA and FA is of great significance for disease diagnosis and food safety monitoring. However, due to the similarity in structural properties between MDA and FA, very few probes for synergistically detecting MDA and FA were reported. In addition, functional abnormalities in the Golgi apparatus are closely related to MDA and FA, but currently there are no fluorescent probes that can detect MDA and FA in the Golgi apparatus. Therefore, we constructed a simple Golgi-targetable fluorescent probe GHA based on hydrazine moiety as the recognition site to produce a pyrazole structure after reaction with MDA and to generate a CN double bond after reaction with FA, allowing MDA and FA to be distinguished due to different emission wavelengths during the recognition process. The probe GHA has good specificity and sensitivity. Under the excitation of 350 nm, the blue fluorescence was significantly enhanced at 424 nm when the probe reacted with MDA, and the detection limit was 71 nM. At the same time, under the same excitation of 350 nm, the reaction with FA showed a significant enhancement of green fluorescence at 520 nm, with a detection limit of 12 nM for FA. And the simultaneous and high-resolution imaging of MDA and FA in the Golgi apparatus of cells was achieved. In addition, the applications of the probe GHA in food demonstrated it can provide a powerful method for food safety monitoring. In summary, this study offers a promising tool for the synergistic identification and determination of MDA and FA in the biosystem and food, facilitating the revelation of their detailed functions in Golgi apparatus and the monitoring of food safety.

Selectively lighting up glyoxal in living cells using an o-phenylenediamine fused hemicyanine

Glyoxal (GL) is a reactive α-dicarbonyl compound generated from glycated proteins in the Maillard reaction. It has attracted particular attention over the past few years because of its possible clinical significance in chronic and age-related diseases. In this work, a reaction-based red emission fluorescent probe GL1 has been synthesized successfully by grafting an alkyl group onto an amino group to regulate its selectivity for GL. Under physiological conditions, the fluorescence intensity of GL1 at 640 nm obviously increased with the increase of GL concentration, and it exhibited high selectivity for GL over other reactive carbonyl compounds, as well as a lower detection limit (0.021 μM) and a larger Stokes shift (112 nm). At the same time, GL1 can selectively accumulate in mitochondria and can be used to detect exogenous and endogenous GL in living cells with low cytotoxicity.

Bio-Inspired Carbon Dots as Malondialdehyde Indicator for Real-Time Visualization of Lipid Peroxidation in Depression

Brain lipidic peroxidation is closely associated with the pathophysiology of various psychiatric diseases including depression. Malondialdehyde (MDA), a reactive aldehyde produced in lipid region, serves as a crucial biomarker for lipid peroxidation. However, techniques enabling real-time detection of MDA are still lacking due to the inherent trade-off between recognition dynamics and robustness. Inspired by the structure of phospholipid bilayers, amphiphilic carbon dots named as CG-CDs targeted to cell membrane are designed for real-time monitoring of MDA fluctuations. The design principle relies on the synergy of dynamic hydrogen bonding recognition and cell membrane targetability. The latter facilitates the insertion of CG-CDs into lipid regions and provides a hydrophobic environment to stabilize the labile hydrogen bonding between CG-CDs and MDA. As a result, recognition robustness and dynamics are simultaneously achieved for CG-CDs/MDA, allowing for in situ visualization of MDA kinetics in cell membrane due to the instant response (<5 s), high sensitivity (9-fold fluorescence enhancement), intrinsic reversibility (fluorescence on/off), and superior selectivity. Subsequently, CG-CDs are explored to visualize nerve cell membrane impairment in depression models of living cells and zebrafish, unveiling the extensive heterogeneity of the lipid peroxidation process and indicating a positive correlation between MDA levels and depression.

Fluorescent Probes for Disease Diagnosis

The identification and detection of disease-related biomarkers is essential for early clinical diagnosis, evaluating disease progression, and for the development of therapeutics. Possessing the advantages of high sensitivity and selectivity, fluorescent probes have become effective tools for monitoring disease-related active molecules at the cellular level and in vivo. In this review, we describe current fluorescent probes designed for the detection and quantification of key bioactive molecules associated with common diseases, such as organ damage, inflammation, cancers, cardiovascular diseases, and brain disorders. We emphasize the strategies behind the design of fluorescent probes capable of disease biomarker detection and diagnosis and cover some aspects of combined diagnostic/therapeutic strategies based on regulating disease-related molecules. This review concludes with a discussion of the challenges and outlook for fluorescent probes, highlighting future avenues of research that should enable these probes to achieve accurate detection and identification of disease-related biomarkers for biomedical research and clinical applications.

Assessing chronic gestational exposure to environmental chemicals in pregnant women: Advancing the co-PBK model

Vulnerable populations, such as pregnant women and their fetuses, confront potential health risks due to exposure to environmental toxic compounds. Computational methods have been popular in assessing chemical exposure to populations, contrasting with traditional cohort studies for human biomonitoring. This study proposes a screening-level approach based on physiologically based kinetic (PBK) modeling to evaluate the steady-state exposure of pregnant women to environmental chemicals throughout pregnancy. To exemplify the modeling application, naphthalene was chosen. Simulation results indicated that maternal fat exhibited significant bioaccumulation potential, with the log-transformed BTF of naphthalene at 0.51 mg kg-1 per mg d-1 in the steady state. The placenta was primarily exposed to 0.83 mg/d naphthalene for a 75.2 kg pregnant woman, considering all exposure routes. In the fetal structure, single-organ fetal PBK modeling estimated a naphthalene exposure of 123.64 mg/d to the entire fetus, while multiple-organ fetal PBK modeling further revealed the bioaccumulation highest in fat tissue. The liver identified as the vital organ for metabolism, kBioT,LiverM was demonstrated with the highest sensitivity among rate constants in the maternal body. Furthermore, the first-order kinetic rate constants related to the placenta and blood were found to impact the distribution process of naphthalene in the fetus, influencing gestational exposure. In conclusion, urgent attention is needed to develop a computational biomonitoring tool for assessing toxic chemical exposure in vulnerable populations.

A new multi-parameter imaging platform for in vivo drug efficacy evaluation of ischemic stroke

Ischemic stroke with high incidence and disability rate severely endangers human health. Current clinical treatment strategies are quite limited, new drugs for ischemic stroke are urgently needed. However, most existing methods for the efficacy evaluation of new drugs possess deficiencies of divorcing from the true biological context, single detection indicator and complex operations, leading to evaluation biases and delaying drug development process. In this work, leveraging the advantages of fluorescence imaging with non-invasive, real-time, in-situ, high selectivity and high sensitivity, a new multi-parameter simultaneous fluorescence imaging platform (MPSFL-Platform) based on two fluorescence materials was constructed to evaluate the efficacy of new drug for ischemic stroke. Through simultaneous fluorescence observing three key indicators of ischemic stroke, malondialdehyde (MDA), formaldehyde (FA), and monoamine oxidase A (MAO-A), the efficacy evaluations of three drugs for ischemic stroke were real-time and in-situ performed. Compared with edaravone and butylphthalide, edaravone dexborneol exhibited better therapeutic effect by using MPSFL-Platform. The successful establishment of MPSFL-Platform is serviceable to accelerate the conduction of preclinical trial and the exploration of pathophysiology mechanism for drugs related to ischemic stroke and other brain diseases, which is perspective to promote the efficiency of new drug development.

Fluorescence probe for real-time malonaldehyde detection in epilepsy model

Oxidative stress, a condition involving an imbalance between reactive oxygen species (ROS) and antioxidants, is closely linked to epilepsy, contributing to abnormal neuronal excitability. This study introduces a novel fluorescent probe, the MDP probe, designed for the efficient detection of malondialdehyde (MDA), a critical biomarker associated with oxidative stress. The MDP probe offers several key advantages, including high sensitivity with a low detection limit of 0.08 μM for MDA, excellent selectivity for MDA even in the presence of interfering substances, and biocompatibility, making it suitable for cell-based experiments. The probe allows for real-time monitoring of MDA levels, enabling dynamic studies of oxidative stress. In vivo experiments in mice demonstrate its potential for monitoring MDA levels, particularly in epilepsy models, which could have implications for disease research and diagnosis. Overall, the MDP probe represents a promising tool for studying oxidative stress, offering sensitivity and specificity in cellular and in vivo settings. Its development opens new avenues for exploring the role of oxidative stress in various biological processes and diseases, contributing to advancements in healthcare and biomedical research.

Shedding Light on Lysosomal Malondialdehyde Affecting Vitamin B12 Transport during Cerebral Ischemia/Reperfusion Injury

Cerebral ischemia-reperfusion injury (CIRI) is often accompanied by upregulation of homocysteine (Hcy). Excessive Hcy damages cerebral vascular endothelial cells and neurons, inducing neurotoxicity and even neurodegeneration. Normally, supplementation of vitamin B12 is an ideal intervention to reduce Hcy. However, vitamin B12 therapy is clinically inefficacious for CIRI. Considering oxidative stress is closely related to CIRI, the lysosome is the pivotal site for vitamin B12 transport. Lysosomal oxidative stress might hinder the transport of vitamin B12. Whether lysosomal malondialdehyde (lysosomal MDA), as the authoritative biomarker of lysosomal oxidative stress, interferes with the transport of vitamin B12 has not been elucidated. This is ascribed to the absence of effective methods for real-time and in situ measurement of lysosomal MDA within living brains. Herein, a fluorescence imaging agent, Lyso-MCBH, was constructed to specifically monitor lysosomal MDA by entering the brain and targeting the lysosome. Erupting the lysosomal MDA level in living brains of mice under CIRI was first observed using Lyso-MCBH. Excessive lysosomal MDA was found to affect the efficacy of vitamin B12 by blocking the transport of vitamin B12 from the lysosome to the cytoplasm. More importantly, the expression and function of the vitamin B12 transporter LMBD1 were proved to be associated with excessive lysosomal MDA. Altogether, the revealing of the lysosomal MDA-LMBD1 axis provides a cogent interpretation of the inefficacy of vitamin B12 in CIRI, which could be a prospective therapeutic target.

Recent progress of oxidative stress associated biomarker detection

Oxidative stress denotes the imbalance between the generation of reactive oxygen species (ROS) and antioxidant defenses in living organisms, participating in various pathophysiological processes and mediating the occurrence of diseases. Typically, the excessive production of ROS under oxidative stress elicits oxidative modification of biomacromolecules, including lipids, proteins and nucleic acids, leading to cell dysfunction and damage. Therefore, the analysis and detection of oxidative stress-associated biomarkers are of considerable importance to accurately reflect and evaluate the oxidative stress status. This review comprehensively elucidates the recent advances and applications of imaging probes for tracking and detecting oxidative stress-related biomarkers such as lipid peroxidation, and protein and DNA oxidation. The existing challenges and future development directions in this field are also discussed.

Semicarbazide-based fluorescent probe for detection of Cu2+ and formaldehyde in different channels

Two fluorescent sensors with the receptor semicarbazide respectively at 7- (CAA) and 3-position (CAB) of coumarin were designed and synthesized. CAA exhibits fluorescence turn-on response to Cu²⁺ by triggering the intramolecular charge transfer (ICT) process via Cu²⁺-catalyzed hydrolysis, and can detect formaldehyde (FA) at different channel by inhibiting the photo-induced electron transfer (PET). However, CAB displays quite different responses: the photophysical properties hardly changed in the presence of FA; while a three-stage fluorescence response of fast quenching, steady increasing and slowly decreasing was found upon addition of Cu²⁺. The high selectivity enabled CAA a good candidate for quantification of Cu²⁺ and formaldehyde as well as bioimaging Cu²⁺ in living cells. Good linear relationships between the fluorescence intensity and analyte concentration were observed in the range of 0.1-30 μM for Cu²⁺ and 1.0-50 μM for FA, and their detection limits (LOD) were calculated to be 0.43 μM and 1.92 μM (3δ/k), respectively.