Ratiometric luminescent simultaneous sensing of aristolochic acids (I-IV) by a novel metal-organic framework and its nanowire.

Aristolochic acids (AAs), which are a group of nitrophenanthrene carboxylic acids formed by Aristolochia plant, have become an increasing serious threat to humans due to their nephrotoxicity and carcinogenicity. Fast and accurate approaches capable of simultaneous sensing of aristolochic acids (I-IV) are vital to avoid intake of such compounds. In this research, the novel ratiometric fluorescence zinc metal-organic framework and its nanowire have been prepared. The two different coordination modes (tetrahedral configuration and twisted triangular bipyramidal configuration) within zinc metal-organic framework lead to the significant double emissions. The ratiometric fluorescence approach based on nanowire provides a broader concentration range (3.00 × 10-7~1.00 × 10-4 M) and lower limit of detection (3.70 × 10-8 M) than that based on zinc metal-organic framework (1.00 × 10-6~1.00 × 10-4 M, 5.91 × 10-7 M). The RSDs of the results are in the range 1.4-3.5% (nanowire). The density functional theory calculations and UV-Vis absorption verify that the sensing mechanism is due to charge transfer and energy transfer. Excellent spiked recoveries for AAs(I-IV) in soil and water support that nanowire is competent to simultaneously detect these targets in real samples, and the proposed approach has potential as a fluorescence sensing platform for the simultaneous detection of AAs (I-IV) in complex systems.

A green micelle-enhanced first derivative synchronous fluorescence approach for determination of donepezil HCl and trazodone HCl in their pure state, pharmaceutical dosage form and spiked human plasma.

The study's objective is to establish an eco-friendly, sensitive and economical quantitative methodology for the concurrent analysis of donepezil HCl (DPZ) and trazodone HCl (TRZ) in raw materials, tablets and human plasma. The first derivative synchronous fluorescence spectroscopic (FDSFS) technique was applied at constant wavelength difference (∆λ = 120) for assessment of DPZ and TRZ at each other's zero-crossing point at 279 nm and 297 nm, respectively. The submitted technique was validated in accordance with ICH Q2 R1 guidelines and the linearity of the standard calibration curve was observed over the concentration range of 10-500 ng/ml for DPZ and 20-1,000 ng/ml for TRZ. The detection limits (LOD) were found to be 2.65 and 5.4 ng/ml, and the limits of quantitation (LOQ) were 8.05 and 16.3 ng/ml for DPZ and TRZ, respectively. This technique was used further to quantify the studied medications in their laboratory-prepared mixtures, commercial tablets and spiked plasma samples. The results obtained were not significantly different from those acquired from the comparison methods, indicating the high accuracy and precision of the proposed method. Furthermore, the ecological friendliness of the suggested method was evaluated and proven to be excellent using Green Analytical Procedure Index (GAPI) and Analytical GREEnness (AGREE) evaluation tools.

Inactivation of polyphenol oxidase by low intensity DC field: Experiment and mechanism analysis via molecular dynamics simulation and molecular docking.

In this study, inactivation of mushroom polyphenol oxidase (PPO) by low intensity direct current (DC) electric field and its molecular mechanism were investigated. In the experiments under 3 V/cm, 5 V/cm, 7 V/cm and 9 V/cm electric fields, PPOs were all completely inactivated after different exposure times. Under 1 V/cm, a residual activity of 11.88 % remained. The inactivation kinetics confirms to Weibull model. Under 1-7 V/cm, n value closes to a constant about 1.3. The structural analysis of PPO under 3 V/cm and 5 V/cm by fluorescence emission spectroscopy and molecular dynamics (MD) simulation showed that the tertiary structure was slightly changed with increased radius of gyration, higher potential energy and rate of C-alpha fluctuation. After exposure to the electric field, most of the hydrophobic tryptophan (TRP) residues turned to the hydrophilic surface, resulting the fluorescence red-shifted and quenched. Molecular docking indicated that the receptor binding domain of catechol in PPO was changed. PPO under electric field was MD simulated the first time, revealing the changing mechanism of the electric field itself on PPO, a binuclear copper enzyme, which has a metallic center. All these suggest that the low intensity DC electric field would be a promising option for enzymatic browning inhibition or even enzyme activity inactivation.

Magnetic beads and GO-assisted enzyme-free signal amplification fluorescent biosensors for disease diagnosis.

Cancer detection is still a major challenge in public health. Identification of oncogene is the first step toward solving this problem. Studies have revealed that various cancers are associated with miRNA expression. Therefore, the sensitive detection of miRNA is substantially important to solve the cancer problem. In this study, let-7a, a representative substance of miRNA, was selected as the detection target. With the assistance of magnetic beads commonly used in biosensors and self-synthesized graphene oxide materials, specificity and sensitivity detection of the target gene let-7a were achieved via protease-free signal amplification. The limit of detection (LOD) was as low as 15.015pM. The fluorescence signal intensity showed a good linear relationship with the logarithm of let-7a concentration. The biosensor could also detect let-7a in complex human serum samples. Overall, this fluorescent biosensor is not only simple to operate, but also strongly specificity to detect let-7a. Therefore, it has substantial potential for application in the early diagnosis of clinical medicine and biological research.

Dual-mode fluorescence and colorimetric smartphone-based sensing platform with oxidation-induced self-assembled nanoflowers for sarcosine detection.

BACKGROUND: Early prostatic cancer (PCa) diagnosis significantly improves the chances of successful treatment and enhances patient survival rates. Traditional enzyme cascade-based early cancer detection methods offer efficiency and signal amplification but are limited by cost, complexity, and enzyme dependency, affecting stability and practicality. Meanwhile, sarcosine (Sar) is commonly considered a biomarker for PCa development. It is essential to develop a Sar detection method based on cascade reactions, which should be efficient, low skill requirement, and suitable for on-site testing. RESULTS: To address this, our study introduces the synthesis of organic-inorganic self-assembled nanoflowers to optimize existing detection methods. The Sar oxidase (SOX)-inorganic hybrid nanoflowers (Cu3(PO4)2:Ce@SOX) possess inherent fluorescent properties and excellent peroxidase activity, coupled with efficient enzyme loading. Based on this, we have developed a dual-mode multi-enzyme cascade nanoplatform combining fluorescence and colorimetric methods for the detection of Sar. The encapsulation yield of Cu3(PO4)2:Ce@SOX reaches 84.5 %, exhibiting a remarkable enhancement in catalytic activity by 1.26-1.29 fold compared to free SOX. The present study employing a dual-signal mechanism encompasses 'turn-off' fluorescence signals ranging from 0.5 µM to 60 µM, with a detection limit of 0.226 µM, and 'turn-on' colorimetric signals ranging from 0.18 µM to 60 µM, with a detection limit of 0.120 µM. SIGNIFICANCE: Furthermore, our study developed an intelligent smartphone sensor system utilizing cotton swabs for real-time analysis of Sar without additional instruments. The nano-platform exhibits exceptional repeatability and stability, rendering it well-suited for detecting Sar in authentic human urine samples. This innovation allows for immediate analysis, offering valuable insights for portable and efficient biosensors applicable to Sar and other analytes.

A fluorescent terbium-metal-organic framework material for high-sensitivity detection of vomitoxin and oxytetracycline hydrochloride in water.

A unique luminescent lanthanide metal-organic framework (LnMOF)-based fluorescence detection platform was utilized to achieve sensitive detection of vomitoxin (VT) and oxytetracycline hydrochloride (OTC-HCL) without the use of antibodies or biomolecular modifications. The sensor had a fluorescence quenching constant of 9.74 × 106 M-1 and a low detection limit of 0.68 nM for vomitoxin. Notably, this is the first example of a Tb-MOF sensor for fluorescence detection of vomitoxin. We further investigated its response to two mycotoxins, aflatoxin B1 and ochratoxin A, and found that their Stern-Volmer fluorescence quenching constants were lower than those of VT. In addition, the fluorescence sensor realized sensitive detection of OTC-HCL with a detection limit of 0.039 µM. In conclusion, the method has great potential as a sensitive and simple technique to detect VT and OTC-HCL in water.

An ingenious technique based on the usage of fluorone-based dye; pyrosin B in prucalopride assay in different matrices through an "on-off" dye native fluorescence probe.

Prucalopride (PCD), is a modern medication approved by the United States in 2018 to alleviate constipation caused by motility issues. PCD demonstrates a strong affinity and selectivity toward the 5-HT4 receptor. The study here introduces a feasible, direct, non-extractive, and affordable pathway for PCD analytical tracking. The fluorimetric study is based on the on-off effect on the emission amplitude of fluorone-based dye (pyrosin B). In a one-pot experiment, the complex between PCD and pyrosin B is formed instantly in an acidic medium. Correlation between decreased pyrosin B emission and PCD concentrations provides a linear calibration plot from 50 to 900 ng/mL. PCD-dye complex system affecting variables were meticulously tuned. The values of the estimated limit of quantitation and limit of detection for the current methodology were 47.5 and 15.7 ng/mL, respectively. Conformity of the strategy validity was achieved by a comprehensive study of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use criteria. The method was convincingly applied for PCD assay in tablets and content uniformity investigation. Furthermore, PCD tracking in the spiked biological fluid was applied. Finally, the method uses distilled water as dispersing medium which rise accommodation with the green chemistry principle.

Analytical Aspects of ANSA-BSA Association: A Thermodynamic and Conformational Approach.

Many studies have demonstrated the manner in which ANS interacts with bovine serum albumin (BSA), although they are limited by the extremely low solubility of dye. The present study demonstrates the binding of ANSA dye with BSA, and since this dye can easily replace ANS, it not only simplifies research but also improves sensor accuracy for serum albumin. A combination of calorimetry and spectroscopy has been employed to establish the thermodynamic signatures associated with the interaction of ANSA with the protein and the consequent conformational changes in the latter. The results of differential scanning calorimetry reveal that when the concentration of ANSA in solution is increased, the thermal stability of the protein increases substantially. The fluorescence data demonstrated a decrease in the binding affinity of ANSA with the protein when pH increased but was unable to identify a change in the mode of interaction of the ligand. ITC has demonstrated that the mode of interaction between ANSA and the protein varies from a single set of binding sites at pH 5 and 7.4 to a sequential binding site at pH 10, emphasizing the potential relevance of protein conformational changes. TCSPC experiments suggested a dynamic type in the presence of ANSA. Molecular docking studies suggest that ANSA molecules are able to find ionic centers in the hydrophobic pockets of BSA. The findings further imply that given its ease of use in experiments, ANSA may be a useful probe for tracking the presence of serum albumin and partially folded protein states.

Spectral characterization, degradation behavior, quenching, and semi-quantification of fluoroquinolone antibiotics in the antibiotic-humic mixture using fluorescence spectroscopy.

Antibiotics, one of the significant emerging contaminants, are intensifying their continual spread out into the environment and affecting human health and the ecosystem in the developing country Bangladesh. This study characterizes widely used fluoroquinolone (FQ) antibiotics, formulates the method to spectrally distinguish them from ubiquitous, and important reactive, adsorbent, and altering catalytic macromolecule humic substances (HS), and further quantifies them using fluorescence spectroscopy. The presence of identical fluorophore at Excitation/Emission = 225-230/285-295 nm wavelength, possession of fluorescence spectra at short emission wavelength (<350 nm) during 275 nm excitation, different emission maxima, and various fluorescing components in antibiotics identified through three-dimensional excitation-emission matrix (EEM) and parallel factor analysis (PARAFAC) models distinguished them from the humic substance as well as from each other. Stern-Volmer equation and its modified version were applied to identify quenching and binding capability, and fluorescence intensity quenching rate of antibiotics and humic in their mixture. Unlike poor and inconsistent quenching mechanisms of humic, FQ antibiotics reduced HS intensity throughout the entire photo-irradiation experiment affirming the functioning of the stable quenching methods. Static quenching of fluorophores was identified from the redshift of excited wavelength on the electronic ground state. Temperature differences during daylight and dark conditions played contrasting roles during the fluorescence quenching of FQ. Unique spectral response at emission wavelength < 350 nm during 275 nm excitation in FQ was considered as its least intensity in the antibiotic-humic mixture and was also used to formulate distinct spectral pattern of each FQ antibiotic. The study also identified the traces of FQ antibiotics with various intensities at different lakes in Bangladesh.

Ultrafast Energy Transfer in a Diatom Photosystem II Supercomplex.

The light-harvesting complexes (LHCs) of diatoms, specifically fucoxanthin-Chl a/c binding proteins (FCPs), exhibit structural and functional diversity, as highlighted by recent structural studies of photosystem II-FCP (PSII-FCPII) supercomplexes from different diatom species. The excitation dynamics of PSII-FCPII supercomplexes isolated from the diatom Thalassiosira pseudonana was explored using time-resolved fluorescence spectroscopy and two-dimensional electronic spectroscopy at room temperature and 77 K. Energy transfer between FCPII and PSII occurred remarkably fast (<5 ps), emphasizing the efficiency of FCPII as a light-harvesting antenna. The presence of long-wavelength chlorophylls may further help concentrate excitations in the core complex and increase the efficiency of light harvesting. Structure-based calculations reveal remarkably strong excitonic couplings between chlorophylls in the FCP antenna and between FCP and the PSII core antenna that are the basis for the rapid energy transfer.

Deeper Insights into Mixed Crowding through Enzyme Activity, Dynamics, and Crowder Diffusion.

Given the fact that the cellular interior is crowded by many different kinds of macromolecules, it is important that in vitro studies be carried out in the presence of mixed crowder systems. In this regard, we have used binary crowders formed by the combination of some of the commonly used crowding agents, namely, Ficoll 70, Dextran 70, Dextran 40, and PEG 8000 (PEG 8), to study how these affect enzyme activity, dynamics, and crowder diffusion. The enzyme chosen is AK3L1, an isoform of adenylate kinase. To investigate its dynamics, we have carried out three single point mutations (A74C, A132C, and A209C) with the cysteine residues being labeled with a coumarin-based solvatochromic probe [CPM: (7-diethylamino-3-(4-maleimido-phenyl)-4-methylcoumarin)]. Both enzyme activity and dynamics decreased in the binary mixtures as compared with the sum of the individual crowders, suggesting a reduction in excluded volume (in the mixture). To gain deeper insights into the binary mixtures, fluorescence correlation spectroscopy studies were carried out using fluorescein isothiocyanate-labeled Dextran 70 and tetramethylrhodamine-labeled AK3L1 as the diffusion probes. Diffusion in binary mixtures was observed to be much more constrained (relative to the sum of the individual crowders) for the labeled enzyme as compared to the labeled crowder showing different environments being faced by the two species. This was further confirmed during imaging of the phase-separated droplets formed in the binary mixtures having PEG as one of the crowding agents. The interior of these droplets was found to be rich in crowders and densely packed, as shown by confocal and digital holographic microscopy images, with the enzymes predominantly residing outside these droplets, that is, in the relatively less crowded regions. Taken together, our data provide important insights into various aspects of the simplest form of mixed crowding, that is, composed of just two components, and also hint at the enhanced complexity that the cellular interior presents toward having a detailed and comprehensive understanding of the same.

Fluorescence in depth: integration of spectroscopy and imaging with Raman, IR, and CD for advanced research.

Fluorescence spectroscopy serves as a vital technique for studying the interaction between light and fluorescent molecules. It encompasses a range of methods, each presenting unique advantages and applications. This technique finds utility in various chemical studies. This review discusses Fluorescence spectroscopy, its branches such as Time-Resolved Fluorescence Spectroscopy (TRFS) and Fluorescence Lifetime Imaging Microscopy (FLIM), and their integration with other spectroscopic methods, including Raman, Infrared (IR), and Circular Dichroism (CD) spectroscopies. By delving into these methods, we aim to provide a comprehensive understanding of the capabilities and significance of fluorescence spectroscopy in scientific research, highlighting its diverse applications and the enhanced understanding it brings when combined with other spectroscopic methods. This review looks at each technique's unique features and applications. It discusses the prospects of their combined use in advancing scientific understanding and applications across various domains.

Hydrazone-linked covalent organic framework functionalized with cysteine as a fluorescence sensor and Exploration of paper chip for p-nitrophenol detection.

The large use and emission of p-nitrophenol (p-NP) seriously pollute the environment and endanger human health. In this work, a hydrazone-linked fluorescent covalent organic framework (BATHz-COF) was simply synthesized at room temperature and covalently linked N-acetyl-L-cysteine (NALC) via the "thiol-ene" click reaction, where carboxyl groups were introduced to improve dispersion and fluorescence intensity. As a rapid, good selectivity and reusability fluorescence sensor, the obtained COF-NALC has been used for quantitative analysis of p-NP predicated on the internal filtering effect (IFE). Under optimal conditions, COF-NALC enabled quantitative detection of p-NP with a linear range of 5-50 µM and the detection limit was 1.46 µM. The application of COF-NALC to the detection of p-NP in river water samples was successful, and the satisfactory recoveries were 98.0%-109.3%. Furthermore, the fluorescent COF paper chips constructed by in situ growth were combined with a smartphone to build a visual platform for the quick and real-time detection of p-NP, providing an excellent illustration for the development of intelligent fluorescence sensing in environmental analysis.

A new biphenol-dipicolylamine based ligand and its dinuclear Zn2+ complex as fluorescent sensors for ibuprofen and ketoprofen in aqueous solution.

In this work, the study of the new ligand 3,3'-bis[N,N-bis(pyridine-2-ylmethyl)aminomethyl]-2,2'-dihydroxybiphenyl (L) is reported, where a central 2,2'-biphenol (BPH) fluorophore was functionalized at 3,3'-positions with two dipicolylamine (DPA) side arms as receptor units. Following the synthesis and full chemical-physical characterization, the acid-base and Zn2+-coordination abilities of L were investigated through a combination of potentiometric, UV-Vis, fluorescence, NMR, XRD and DFT measurements. The optical properties of the ligand turned out to be strongly dependent on the pH, being straightforwardly associated with the protonation state of the BPH moiety, whereas its peculiar design allowed to form stable mono and dinuclear Zn2+ complexes. In the latter species, the presence of two Zn2+ ions coordinatively unsaturated and placed at close distance to each other, prompted us to test their usefulness as metallo-receptors for two environmental pollutants of great relevance, ibuprofen and ketoprofen. Potentiometric and fluorescence investigations evidenced that these important non-steroidal anti-inflammatory drugs (NSAIDs) are effectively coordinated by the metallo-receptors and, of relevance, both the stability and the fluorescence properties of the resulting ternary adducts are markedly affected by the different chemical architectures of the two substrates. This study aims at highlighting the promising perspectives arising from the use of polyamino phenolic ligands as chemosensors for H+/Zn2+ and other additional anionic targets in their metal-complexed forms.

A facile and intelligent detection method for diclazuril based on a stable dual emissive Eu3+-dopped metal-organic framework.

Diclazuril (DIC) is a broad-spectrum anti-coccidiosis drug of the triazine class, widely used in poultry farming. The overuse of DIC may lead to its accumulation in animal bodies, which may enter the food chain and threaten human health. In this work, we fabricated a stable Eu3+-doped UiO-66 fluorescence sensor (EuUHIPA-30) for the sensitive detection of DIC. Among 20 veterinary drugs, the fluorescence of EuUHIPA-30 selectively responds to DIC, with a low detection limit (0.19 µM) and fast response (10 s). EuUHIPA-30 is recyclable and can detect DIC in chicken and eggs with good recoveries. Moreover, a smartphone-integrated paper-based sensor enables the instrument-free, rapid, visual, and intelligent detection of DIC in chickens and eggs. This work provides a promising candidate for practical fluorescent DIC sensing in animal-derived food to promote food safety.

A novel near-infrared polymethine dye biosensor for rapid and selective detection of lithocholic acid.

Lithocholic acid (LCA), a secondary bile acid, has emerged as a potential early diagnostic biomarker for various liver diseases. In this study, we introduce a novel near-infrared (NIR) polymethine dye-based biosensor, capable of sensitive and selective detection of LCA in phosphate buffer and artificial urine (AU) solutions. The detection mechanism relies on the formation of J-aggregates resulting from the interplay of 3,3-Diethylthiatricarbocyanine iodide (DiSC2(7)) dye molecules and LCA, which induces a distinctive red shift in both absorption and fluorescence spectra. The biosensor demonstrates a detection limit for LCA of 70 µM in PBS solution (pH 7.4), while in AU solution, it responds to an LCA concentration as low as ∼60 µM. Notably, the proposed biosensor exhibits outstanding selectivity for LCA, effectively distinguishing it from common interferents such as uric acid, ascorbic acid, and glucose. This rapid, straightforward, and cost-effective spectrometer-based method underscores its potential for early diagnosis of liver diseases by monitoring LCA concentrations.

Strategies for measuring concentrations and forms of amyloid-ß peptides.

Alzheimer's disease (AD) is affecting more and more people worldwide without the effective treatment, while the existed pathological mechanism has been confirmed barely useful in the treatment. Amyloid-ß peptide (Aß), a main component of senile plaque, is regarded as the most promising target in AD treatment. Aß clearance from AD brain seems to be a reliably therapeutic strategy, as the two exited drugs, GV-971 and aducanumab, are both developed based on it. However, doubt still exists. To exhaustive expound on the pathological mechanism of Aß, rigorous analyses on the concentrations and aggregation forms are essential. Thus, it is attracting broad attention these years. However, most of the sensors have not been used in pathological studies, as the lack of the bridge between analytical chemist and pathologists. In this review, we made a brief introduce on Aß-related pathological mechanism included in ß-amyloid hypothesis to elucidate the detection conditions of sensor methods. Furthermore, a summary of the sensor methods was made, which were based on Aß concentrations and form detections that have been developed in the past 10 years. As the greatest number of the sensors were built on fluorescent spectroscopy, electrochemistry, and Roman spectroscopy, detailed elucidation on them was made. Notably, the aggregation process is another important factor in revealing the progress of AD and developing the treatment methods, so the sensors on monitoring Aß aggregation processes were also summarized.

A naphthalimide-based portable fluorescent sensor integrated with a photoelectric converter for rapid and on-site detection of type II pyrethroids in celery.

The on-site detection of pyrethroids, particularly type II pyrethroids, remains a challenging task in complex vegetable samples. Herein, a novel method based on naphthalimide was developed to realize the specific detection of type II pyrethroids by hydrolyzing and utilizing the compound m-phenoxybenzaldehyde (3-PBD). Hydrazine group, used as the appropriate moiety, was introduced into the fluorescent dye 1,8-naphthalimide to construct the fluoroprobe NAP. In the presence of 3-PBD, NAP displayed the prominently enhanced fluorescence and also exhibited high selectivity. This proposed method exhibited high anti-inference effects in complex media, realizing sensitive detection of 3-PBD with linear range of 2.15-800 µM and a low detection limit (LOD) of 0.64 µM. The underlying fluorescence-responsive mechanisms were in-depth elucidated by combining spectral analyses with TD-DFT theoretical calculations. Additionally, a direct and rapid hydrolysis method for deltamethrin in celery was established, achieving a high hydrolysis efficiency of >90% within 15 min. Furthermore, a portable fluorescence sensor (PFS) was developed based on high-power LEDs and photodetectors. PFS supplied a LOD of 2.23 µM for 3-PBD and exhibited comparable stability by a fluorescence spectrometer when detecting celery hydrolysate. Moreover, external power source is not required for PFS operations, thereby enabling rapid and on-site detection by transmitting data to a smartphone via bluetooth. These findings extend the academic knowledge in the field of specific pyrethroids detection and contribute to the development of on-site methods for pesticide residual analyses in food matrices.

Catalytic hairpin assembly-based AIEgen/graphene oxide nanocomposite for fluorescence-enhanced and high-precision spatiotemporal imaging of microRNA in living cells.

The low abundance, heterogeneous expression, and temporal changes of miRNA in different cellular locations pose significant challenges for both the detection sensitivity of miRNA liquid biopsy and intracellular imaging. In this work, we report an intelligently assembled biosensor based on catalytic hairpin assembly (CHA) and aggregation-induced emission (AIE), named as catalytic hairpin aggregation-induced emission (CHAIE), for the ultrasensitive detection and intracellular imaging of miRNA-155. To achieve such goal, tetraphenylethylene-N3 (TPE-N3) is used as AIE luminogen (AIEgen), while graphene oxide is introduced to quench the fluorescence. When the target miRNA is present, CHA reaction is triggered, causing the AIEgen to self-assemble with the hairpin DNA. This will restrict the intramolecular rotation of the AIEgen and produce a strong AIE fluorescence. Interestingly, CHAIE does not require any enzyme or expensive thermal cycling equipment, and therefore provides a rapid detection. Under optimal conditions, the proposed biosensor can determine miRNA in the concentration range from 2 pM to 200 nM within 30 min, with the detection limit of 0.42 pM. The proposed CHAIE biosensor in this work offers a low background signal and high sensitivity, making it applicable for highly precise spatiotemporal imaging of target miRNA in living cells.

Inquiry lipaseoring the mechanism of pancreatic lipase inhibition by isovitexin based on multispectral method and enzyme inhibition assay.

Isovitexin is a main natural flavonoid component in various plants. Currently, the inhibitory effect of isovitexin on pancreatic lipase (PL) and its mechanism have not been elucidated yet. In the present study, we investigated the inhibitory effect of isovitexin on PL, as well as its interaction mechanism, using enzyme inhibition methods, spectroscopic analysis, and molecular simulations. Results showed that isovitexin possessed significant PL inhibitory activity, with IC50 values of 0.26 ± 0.02 mM. The interaction between isovitexin and PL was dominated by static quenching, and mainly through hydrogen bonding and hydrophobic interaction forces. Analysis of fluorescence spectroscopy confirmed that isovitexin binding altered the conformation of the PL. Circular dichroism (CD) spectrum indicated that isovitexin altered the secondary structure of PL by decreasing the α-helix content and increasing the ß-fold content. Molecular simulations further characterize the conformational changes produced by the interaction between isovitexin with PL. The performed study may provide a new insight into the inhibitory mechanism of isovitexin as a novel PL inhibitor.