搜索结果：Analytical chemistry

Multidrug-resistant tuberculosis (MDR-TB) remains a major cause of morbidity and mortality worldwide, with people living with HIV experiencing persistently poor treatment outcomes. Clofazimine and bedaquiline are cornerstone drugs in contemporary all-oral MDR-TB regimens, yet their complex pharmacokinetics and substantial interindividual variability complicate regimen optimisation, particularly in vulnerable populations. Robust plasma-based drug quantification is essential to characterise exposure-response relationships and inform individualised therapy. We developed and validated a rapid, sensitive and specific liquid chromatography-tandem mass spectrometry assay for quantifying these drugs in human plasma. The methods were successfully applied on plasma samples from study participants with MDR-TB with or without HIV coinfection who received clofazimine and bedaquiline as part of MDR-TB therapy assessing the Cmax, Tmax and AUC in both groups. The method addresses key analytical challenges posed by clofazimine's extreme lipophilicity and reliably quantifies concentrations across a broad, clinically relevant range, including potentially toxic exposures. Linearity was obtained between 0.0313 to 4.0 mg/L, and the method met bioanalytical method validation criteria along with interlab comparison with a reference laboratory, all within acceptable limits. We observed significantly lower Cmax concentrations of both drugs among HIV-infected participants compared to HIV-uninfected participants (p = 0.011 for clofazimine and p = 0.02 for bedaquiline), highlighting the need for therapeutic drug monitoring in this vulnerable group. This work provides a robust analytical foundation for pharmacokinetic, therapeutic drug monitoring and exposure-response studies of key MDR-TB drugs and supports efforts to optimise treatment outcomes, especially among people living with HIV.

From pre-formulation studies to clinical trials, VEGFR-targeted small-molecule tyrosine kinase inhibitors (TKIs) require rigorous analytical standards. Bioanalysis, stability-indicating studies, and impurity profiling are used to examine chromatographic advances for VEGFR-targeted TKIs like sunitinib, pazopanib, axitinib, sorafenib, cabozantinib, vandetanib, apatinib, lenvatinib, nintedanib, and regorafenib. An LC-MS/MS and UPLC-MS/MS routinely show sub ng/mL performance, as shown by LLOQs (0.2 ng/mL) for sunitinib and axitinib, 1 ng/mL for pazopanib, 5-7 ng/mL for sorafenib, 0.5-1.5 ng/mL for regorafenib metabolic products, and 0.1-0.5 ng/mL for lenvatinib. These approaches are used for pharmacokinetics and therapeutic drug monitoring due to their good correlation coefficient of 0.1-10,000 ng/mL, accuracy of 95%-108%, and precision of 15% RSD. UPLC-QTOF-MS/MS distinguishes degradants and metabolites during forced degradation studies, enabling structural elucidation following ICH M7 risk evaluation protocol. HPTLC/MLC offers fast, sensitive screenings, while RP-HPLC/DAD or HPLC-UV offer reliable, cost-effective routine quality-control solutions with LOD/LOQ in the μg/mL range and linearity of 10-240 μg/mL. This review lists the structures and CAS numbers of ten VEGFR-2 TKI degradants and metabolites, as well as pharmacopeial impurities in SMILES forms. It will be useful for future method development and regulatory applications. To ensure VEGFR-targeted TKI quality, safety, and therapeutic efficacy, LC-MS/MS for trace quantification and HRMS for structure elucidation provide a robust, future-oriented framework. To improve VEGFR-targeted TKI quality, safety, and regulatory compliance, analytical development should focus on HRMS-based impurity characterization, AI-assisted degradation prediction, green chromatography, and harmonized bioanalytical validation.

Chlorine gas is a highly toxic industrial chemical that poses a significant risk in accidental releases and deliberate terrorist attacks. Reliable analytical methods for the determination of chlorine in aqueous samples are therefore required for forensic and environmental investigations. This study aimed to develop a rapid and selective mass spectrometry-based method for chlorine determination following derivatization. Chlorine in aqueous samples was derivatized with methyl 2-(3,4,5-trimethoxyphenyl)acetate (MTMPA) at 50°C for 15 min, yielding methyl 2-(2-chloro-3,4,5-trimethoxyphenyl)acetate (Cl-MTMPA). The derivatization product was analyzed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). While LC-MS/MS analysis was performed directly, GC-MS analysis required an additional liquid-liquid extraction step. Reaction conditions were optimized to maximize derivatization efficiency. The derivatization reaction provided a high yield of Cl-MTMPA under the optimized conditions. GC-MS and LC-MS/MS analyses produced a common major fragment ion at m/z 215.0. Further structural confirmation by liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS) revealed a characteristic product ion at m/z 215.0473 generated from the precursor ion at m/z 275.0681. Calibration curves covering acute toxicologically relevant chlorine concentrations (5-200 mg/L) showed excellent linearity, with correlation coefficients (R2) exceeding 0.99. A rapid and selective derivatization-based method was developed in which the resulting chlorine derivative is readily analyzed by both GC-MS and LC-MS/MS. The method affords reliable analyte identification through characteristic fragmentation and excellent quantitative performance, making it suitable for forensic toxicology and environmental investigations involving chlorine exposure.

Nucleoside and nucleotide analogs are an impactful class of antivirals, yet their efficacy is often limited by inefficient intracellular accumulation and enzymatic activation. Many analogs are administered as nucleoside prodrugs, dependent on host or viral kinases for sequential phosphorylation, with the first monophosphate-forming step widely considered rate-limiting. Medicinal chemistry strategies such as utilizing masked-phosphate prodrugs may improve uptake and activation, but require alternative metabolic processing to generate the active triphosphate. Nanoparticle delivery provides an alternative or complementary approach by directly encapsulating phosphorylated nucleotide analogs. Nanoparticles made from materials including lipids, polymers, dendrimers, or polysaccharides can protect phosphorylated drugs from degradation, improve cellular uptake, and enable controlled or tissue-specific release. This review provides a brief context and overview of recent advances in nanoparticle-mediated delivery of phosphorylated antiviral nucleotides, drawing on parallels from oncology, and evaluates the technological advances and limitations influencing their continued development as antiviral carriers.

Selenosugars are now recognized as the major end metabolites of selenium in mammals and play a central role in selenium detoxification and excretion. Since their discovery in the early 2000s, numerous studies have reported the occurrence of selenosugars in urine, tissues, and biological fluids of humans and animals. However, progress in the field has been hindered by inconsistent nomenclature, analytical limitations, and incomplete understanding of their metabolic origin and biological significance. In this position paper, we provide a comprehensive overview of the chemistry, occurrence, analysis, and metabolism of mammalian selenosugars. We propose a harmonized operational nomenclature that preserves essential structural information while facilitating communication among researchers. We critically evaluate analytical approaches used for selenosugar detection and quantification, including HPLC-ICP-MS, HPLC-ESI-MS, and NMR spectroscopy, and discuss their strengths, limitations, and appropriate applications. Based on accumulated evidence, we recommend minimum analytical criteria for reliable selenosugar identification and reporting. We further review the occurrence of naturally occurring selenosugars in humans and animals and integrate current knowledge into an updated metabolic framework. Adoption of the proposed nomenclature and analytical guidelines should improve consistency across studies and provide a foundation for future investigations into selenium metabolism and homeostasis.

The development of sample preparation methods has led to smaller versions of traditional solid- and liquid-based techniques. This trend aims to align these methods with green analytical chemistry principles by reducing sample and solvent use and enabling more flexible designs, including online and automated systems. However, although miniaturization is often linked to environmental benefits, it also presents significant issues that are sometimes overlooked. These include the continued use of toxic solvents, labor-intensive procedures, and potential health and environmental risks that may be underestimated in the pursuit of "green" solutions. Therefore, this review offers a comprehensive and current overview of both solid- and liquid-based miniaturized techniques, emphasizing their environmental challenges. It focuses on balancing analytical performance with core green chemistry principles. Selected examples from recent literature highlight current applications and trends. Additionally, we discuss emerging directions and ongoing challenges that must be addressed to truly achieve sustainable, green implementation of these methods. We hope this review encourages a more critical perspective among readers and promotes the development of genuinely greener sample preparation strategies across different analytical applications.

Pesticide residues in food matrices pose significant threats to global food safety. Conventional chromatographic methods, though highly reliable, are constrained by high costs, lengthy analysis times, and limited field deployability, restricting their use for rapid on-site monitoring across food supply chains. Nanomaterial-based fluorescent sensing platforms have emerged as promising analytical alternatives, leveraging the unique optical properties of quantum dots (QDs), carbon dots (CDs), Graphene quantum dots (GQDs), metal-organic frameworks (MOFs), and metal nanoclusters (MNCs). This review systematically examines recent advances in these platforms for pesticide detection, with particular emphasis on analytical chemistry perspectives spanning recognition mechanism design, signal transduction, and practical performance in complex food matrices. The structure-property relationships of major pesticide classes and their implications for molecular recognition are first discussed, followed by a systematic analysis of fluorescence modulation mechanisms, including photoinduced electron transfer (PET), Förster resonance energy transfer (FRET), inner filter effect (IFE), and aggregation-induced emission (AIE). Nanomaterial design strategies are further evaluated with respect to synthesis reproducibility, surface functionalization, and batch-to-batch consistency. The integration of artificial intelligence (AI) algorithms for automated signal processing and multi-analyte discrimination is highlighted as a promising approach for improving analytical robustness and quantitative accuracy. Recent advances in device engineering-including smartphone-based sensing platforms, paper-based microfluidic systems, and lateral flow immunoassay (LFIA)-are reviewed with respect to their potential for portable and field-deployable pesticide monitoring in complex food matrices. Finally, key challenges related to matrix interference, large-scale material production, and regulatory validation are discussed, with future directions emphasizing green nanomaterial synthesis, intelligent sensing architectures, and scalable analytical platforms to support distributed food safety monitoring networks.

Analytical methods utilizing the donor-acceptor phenomenon for proguanil (PRGL), an antimalarial medication, that are straightforward, quick, and possess a wide linear dynamic range for drug quantification and its toxicity assessment have not been published in the literature. This study spectrophotometrically validated two economical and effective analytical methods based on the complexation of PRGL with π-acceptors, chloranilic acid (CHLA) and 7,7,8,8-Tetracyanoquinodimethane (TCNQ) along with its Insilco toxicity evaluation using ADMET tool. Multiple analytical variables were examined. The linear dynamic range was notably effective, spanning from 5 to 80 μg mL-1 for CHLA and from 2 to 30 μg mL-1 for TCNQ techniques. The solid charge transfer complexes produced were assessed through different analytical techniques, such as UV-DRS, Fourier transform infrared spectroscopy, TGA-DTA, and powder X-ray diffraction. This study investigated the biological evolution of charge transfer (CT) complexes through the analysis of BSA protein binding and antimicrobial activity. The interaction between the CT complex and BSA was revealed by UV - Vis spectral analysis. The antibacterial efficacy of both CT complexes demonstrates significant effects. The CT complexes may exhibit promising biological activity and could be considered for further investigation as potential bioactive candidates in future studies. The molecular docking results verified the outcomes of the experiment. The outcomes obtained are appropriate for estimating the PRGL in its pharmaceutical formulation. The developed method's greenness was evaluated according to the AGREE guidelines and found satisfactory.

This work introduces an eco-friendly spectrophotometric approach for the simultaneous quantification of methocarbamol (MET) and its impurity product guaifenesin (GUF), based on measuring the second derivative amplitudes of each drug in presence of the other, using zero-crossing technique. The second derivative amplitudes were measured at 208.0 nm and at 207.5 nm for MET and GUF, respectively. The proposed method showed good linearity over the concentration ranges of 1.0-110.0 and 1.0-90.0 µg/mL for MET and GUF, respectively with corresponding correlation coefficient of 0.9997 and 0.9999. The detection and quantitation limits for MET were found to be 0.021 and 0.064 µg/mL, respectively, while GUF corresponding values were 0.013 and 0.041 µg/mL. The method was successfully applied for determining MET and GUF in its dosage forms with high selectivity. The developed method produced comparable results to those obtained by the published reference methods in terms of precision and accuracy. A comprehensive assessment was carried out to evaluate the suggested method's economic feasibility, practicality, and environmental sustainability compared to previously reported techniques. This comprehensive assessment leveraged several state-of-the-art tools, including the analytical Eco-scale, Green Analytical Procedure Index (GAPI), Analytical GREEnness (AGREE), Multi-Color Assessment, Analytical Green Star Area (AGSA) and Blueness Assessment Graphical Index tools. The suggested approach exhibited favorable quadrant profiles in GAPI assessment, along with higher AGREE, AGSA and Eco-scale scores, all of which confirmed their eco-friendliness.

A high-throughput analytical method for quantifying the explosive picric acid (PA) is reported. The approach first involves developing a three-electrode thermoplastic chip, which was then integrated with circular paper structures to generate microfluidic paper-based analytical devices (µPADs). The electrochemical setup was fabricated using a 3D printing pen, a tool commercialized as a toy for kids. The electrochemical chips were initially tested using differential pulse voltammetry to promote the analyte's reduction. After evaluating the PA electrochemical behavior, the µPADs were assembled using a practical procedure with clamps and filter paper. The µPAD assembly was optimized by evaluating the paper substrate, injection volume, and detection potential. Larger-pore papers resulted in a superior response due to greater accessibility of the analyte solution to the electrode surface during injection. Increasing the injection volume enhanced the signal intensity, besides providing better repeatability. Increasing the detection potential enhances the system response. However, this parameter affects selectivity as other species could also be reduced on the electrode surface. Under optimal conditions, the proposed system enabled the sequential injection of an analyte solution into a single device, yielding a sample throughput of (131 ± 14) injections h-1. Furthermore, a linear response was obtained from 10 to 100 µmol L⁻1 picric acid, with a limit of detection of 5.0 µmol L-1. Moreover, the system's applicability was further demonstrated for lake water analyses through recovery studies. Therefore, this work reports a practical analytical tool for the PA quantification in environmental analyses.

SR9009 is a synthetic REV-ERB agonist with potential performance-enhancing properties and is included on the World Anti-Doping Agency (WADA) Prohibited List for human sport. Its potential misuse has also raised concerns in animal sports, particularly equine and camel racing. Although SR9009 metabolism has been investigated in human and equine models, its metabolic fate in racing camels (Camelus dromedarius) remains unclear. Characterizing its biotransformation pathways and identifying suitable biomarkers are essential for developing reliable anti-doping screening strategies for camel racing. An in vitro metabolic study was conducted using camel liver homogenate and the fungal model Cunninghamella elegans. Metabolites were characterized using liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Putative structural elucidation was achieved through accurate mass measurements of precursor and product ions. Diagnostic fragmentation pathways were established using collision-induced dissociation (CID) tandem mass spectrometry (MS/MS), enabling the systematic identification of metabolic modifications based on characteristic fragment ions and neutral losses. Seventeen Phase I metabolites of SR9009 were identified. Major biotransformation pathways included N-dealkylation, mono-hydroxylation, di-hydroxylation, and combinations thereof. The N-dealkylated metabolite was the predominant metabolite detected in both camel liver homogenate and Cunninghamella elegans, indicating its suitability as a primary analytical target for anti-doping screening. No Phase II metabolites were detected under the experimental conditions employed. Putative structural assignments were supported by characteristic high-resolution tandem mass spectral fragmentation patterns. This study provides the first comprehensive metabolic profile of SR9009 in a camel-specific in vitro model. The identification of 17 Phase I metabolites, particularly the predominant N-dealkylated derivative, provides valuable analytical targets for doping control. These findings establish a metabolic foundation for future in vivo studies to determine pharmacokinetics and detection windows in racing camels.

Autoimmune responses are often attributed to failed tolerance to self-proteins, yet protein expression alone cannot explain why certain antigens dominate disease, why autoreactivity emerges under stress, or why specific HLA alleles shape risk. This review presents a framework in which autoimmunity arises from posttranslational remodeling of antigen identity. Rather than limiting PTMs to side chain chemistry, we consider how covalent modifications, altered processing, aberrant translation, peptide recombination, and supramolecular assembly expand the repertoire of molecular forms available for immune recognition. Classical PTMs such as citrullination, deamidation, oxidation, glycosylation, phosphorylation, sulfation, and ubiquitin-like remnants can modify proteolysis, HLA binding, and antibody recognition. Noncanonical pathways, including signal peptide processing, ERAP-dependent trimming, defective ribosomal products, cryptic ORFs, proteasome-catalyzed splicing, and hybrid insulin peptides, further demonstrate that the presented antigenome extends beyond annotated proteins. We also propose that aggregation functions as a supramolecular antigenic modification by altering uptake, persistence, protease accessibility, and local reaction chemistry. Examples from rheumatoid arthritis, celiac disease, type 1 diabetes, multiple sclerosis, systemic lupus erythematosus, inflammatory bowel disease, and autoimmune thyroid disease illustrate how these mechanisms converge. Finally, we discuss mass spectrometry and immunopeptidomics strategies for identifying, validating, and functionally interpreting remodeled antigens in autoimmune disease.

Free fatty acids (FFAs) are bioactive mediators of inflammation, energy metabolism, and membrane remodeling, yet their spatial organization within the Alzheimer's disease (AD) brain and at individual amyloid-β (Aβ) plaques has remained inaccessible. We developed a novel, chemically tailored MALDI workflow that enables simultaneous, spatially resolved detection of nearly 30 FFAs alongside over 100 complex lipid species within the same tissue section. Applying this approach to a transgenic AD mouse model across brain regions and disease stages, and combining it with single-plaque microenvironment analysis (SPMA) that treats each plaque as an individual analytical object, we uncover two previously inaccessible dimensions of plaque-associated lipid biology. FFA distributions form highly structured spatial compartments reflecting regional cytoarchitecture, with distinct enrichment of saturated, monounsaturated, and polyunsaturated species across cortical layers. Within Aβ plaques, nearly 75% of detected FFAs are significantly remodeled, with reciprocal enrichment of short saturated and highly unsaturated species alongside depletion of long-chain monounsaturated FFAs. This pattern is consistent with concurrent disruption of ELOVL-mediated elongation and FADS-mediated desaturation, including opposing enrichment of pro-inflammatory arachidonic acid and pro-resolving docosahexaenoic acid. Machine learning of single-plaque profiles reveals that FFA composition alone classifies plaque age with high accuracy, demonstrating that lipid remodeling continues after Aβ peptide composition has stabilized. Together, these findings establish spatial FFA profiling as a new analytical dimension in neurodegeneration research, revealing that Aβ plaques are dynamic lipid-metabolic microenvironments that continue to remodel long after Aβ deposition has stabilized.

Spectral analysis technology has become an effective method in the field of modern analytical chemistry. However, spectral data has high-dimensional characteristics, and using single variable selection method has limitations. In this research, a hybrid strategy based on uninformative variable elimination (UVE) and discretized wild horse optimizer (DWHO) is proposed to achieve efficient and accurate spectral variable selection. Noise variables were firstly eliminated by UVE and the remaining variables were further refined by DWHO. Partial least squares (PLS) model was built with the selected variable subsets by UVE-DWHO. Four datasets of orange juice, diesel, wine and blood samples were used to validate this method. Compared with full-spectrum PLS, UVE-PLS, Monte Carlo-UVE-PLS (MC-UVE-PLS) and randomization test-PLS (RT-PLS), results showed that the number of selected variables was reduced over 85% by UVE-DWHO-PLS. The lower root mean squared error of prediction (RMSEP) was achieved and the R values were all above 0.95 for the four datasets, indicating that stable and accurate prediction model was successfully established with fewer variables. Therefore, UVE-DWHO provides a valuable new variable selection method for analyzing the spectra of complex samples.

Kanamycin (KANA), a widely used aminoglycoside antibiotic, may accumulate in food products and pose potential risks to human health, calling for sensitive and reliable analytical strategies. A dual-mode detection method integrating surface-enhanced Raman spectroscopy (SERS) with colorimetric sensing was developed. This approach enabled sensitive and rapid detection of KANA. A core-shell Au@CeO2 nanozyme-mediated aptasensor was synthesized, which exhibited oxidase-like activity and enhanced SERS performance. Without KANA, adsorption of the aptamer onto the nanozyme surface inhibited the nanozyme-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), leading to a simultaneous decrease in both SERS and colorimetric signals. Under optimized conditions, the aptasensor enabled quantitative KANA analysis with favorable sensitivity and selectivity, achieving limits of detection of 3.20 × 10-10 mol/L (SERS mode) and 5.10 × 10-6 mol/L (colorimetric mode), with linear ranges of 1.00 × 10-9-1.00 × 10-5 mol/ L (SERS) and 5.00 × 10-5-5.00 × 10-3 mol/L (colorimetric). The practicality of this platform was validated in milk and egg white samples, with recoveries ranging from 98.6% to 107.0% in milk and from 95.6% to 105.0% in egg white. In this strategy, Au@CeO2 is designed to function simultaneously as an oxidase-like nanozyme and a SERS-active substrate. Although the two modes differ in sensitivity and linear range, they provide complementary analytical information: the SERS mode is suitable for trace-level quantitative analysis, whereas the colorimetric mode offers an auxiliary visual response at relatively higher KANA concentrations. This work provides a dual-readout approach for KANA analysis in food samples.

Novel, ternary Ag2O·Co3O4·SrCO3 nanomaterials (NMs) with multifunctionality were synthesized by a simple co-precipitation method. The NMs were characterized by Raman, FTIR, PL, SEM, EDS, and XRD and utilized for the development of a smart bisphenol A (BPA) sensor, photocatalyst, and antibacterial material. Based on the XRD pattern, the average particle size was 66.361 nm, with high crystallinity. The Raman spectra of Ag2O·Co3O4·SrCO3 showed distinct peaks for Ag2O (482 cm-1), Co3O4 (195, 522, 619, and 691 cm-1), and SrCO3 (147 and 1071 cm-1). The photocatalytic activity of NMs in the presence of visible light was assessed using the Crystal Violet (CV) dye, testing the variables pH, temperature, and reusability. After 150 and 120 minutes of exposure to visible light, dosages of 0.08 and 0.09 g in a basic medium (pH 9.2) removed 100% of the dye. The NMs significantly inhibited both Gram-positive and Gram-negative bacteria, showing greater efficacy against Gram-positive bacteria. Consequently, the produced Ag2O·Co3O4·SrCO3 NMs are promising candidates for use in the development of effective photocatalytic systems and antibacterial materials. An advanced electrochemical sensor was engineered by poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) coating onto glassy carbon electrode (GCE) with the synthesized Ag2O·Co3O4·SrCO3 NMs for the highly sensitive and selective detection of BPA via differential pulse voltammetry (DPV). The incorporation of the Ag2O·Co3O4·SrCO3 NMs endowed the sensing interface with superior electrocatalytic activity, enhanced charge-transfer efficiency, and increased surface area and active sites, thereby facilitating efficient redox interactions with BPA molecules. The optimized sensor exhibited a linear detection range (LDR) spanning 10.0-100.0 µM, a limit of detection (LOD) of 6.98 ± 0.35 µM, and an impressive sensitivity of 66.2758 µA µM-1 cm-2, underscoring its analytical efficacy. Electrochemical response studies as a function of pH identified pH 7.0 as the optimal condition, reflecting the sensor's suitability for near-physiological environments. Collectively, these results demonstrate that the Ag2O·Co3O4·SrCO3 NM/PEDOT:PSS/GCE sensor offers a robust, reproducible, and efficient electrochemical platform for the quantitative monitoring of bisphenol A in environmental and biological matrices.

Electrochemiluminescence (ECL) offers high analytical sensitivity, low optical background, and spatially confined light emission at electrode interfaces, enabling a large global market for bead-based ECL immunoassays. Existing ECL instrumentation remains bulky, costly, and largely confined to centralized laboratories with limited access to true spatially resolved imaging. Here, we present a compact, modular ECL imaging platform that enables low-light, spatially resolved, and temporally synchronized electrochemical-optical measurements. The system integrates a Raspberry Pi 4 controller, a monochrome OV9281 global-shutter camera, and an EmStat4s potentiostat, coordinated through open-source Python software providing sub-100 ms synchronization and full control of camera parameters (resolution, exposure, gain, frame rate, and focus). The complete system, of approximately 21 × 15 × 21 cm, has a component bill of materials of 2337 €, which could be reduced to a few hundred euros by using a custom potentiostat, making it substantially more affordable than commercial ECL instruments. Platform performance was validated using both homogeneous solution-phase and heterogeneous bead-based [Ru-(bpy)3]2+/tripropylamine (TPrA) assays on carbon screen-printed electrodes. Synchronized cyclic voltammetry and chronoamperometry captured ECL transient behavior, including onset, peak emission, and decay dynamics. Quantitative bead-based assays showed excellent linearity with low-picomolar range limits of detection, while spatially resolved analysis enabled multiplexed measurements on a single electrode via a region-of-interest readout. These results demonstrate the importance of controlled and optimized camera parameters for quantitative ECL imaging and establish this compact, low-cost, and modular platform as a practical alternative for spatially resolved ECL biosensing and multiplex point-of-care applications.

The endogenous tear peptidome plays essential roles in maintaining ocular homeostasis by stimulating immune response and participating in antimicrobial activity. The biological function of these native peptides is governed by their biochemical properties, including peptide length, charge, and hydrophobicity. Accordingly, the production of native peptides within the tear film is tightly regulated through a complex interplay between circulating proteases and the proteolytic susceptibility of the protein substrate. Though glycosylation has been shown to regulate the proteolysis of specific proteins in vitro, the extent to which endogenous cleavage motifs are mediated by proximal O-glycans remains unexplored in a complex biofluid. Furthermore, the existence and identity of native tear peptides bearing O-glycans have yet to be elucidated, largely due to the high analytical complexity of tear fluid and the difficulty in characterizing O-glycosylated peptides. To address this gap, we leveraged advances in mass spectrometry (MS) to provide the first observation of extracellular tear O-glycopeptides, detailing their biochemical properties and overall glycan compositions. Beyond systematic profiling of the O-glycopeptidome, we employed site-specific glycoproteomic analysis followed by molecular dynamics to investigate the correlation between O-glycan proximity and proteolysis. Here, we observed that O-glycans preferentially occupy glycosites distal from the N-/C-terminus, which was associated with distinct cleavage motifs and peptide backbones. We then showed in silico that O-glycosylation on lacritin can mediate the solvent accessibility of proximal cleavage residues, thus providing a structural basis for these observations. Finally, cleavage studies of glycosylated and nonglycosylated lacritin revealed that the unmodified form exhibited significantly greater degradation by endogenous tear proteases, supporting a protective role for its glycans. Taken together, this study defines the proteolytic landscape at the ocular surface and highlights a potential role for tear fluid O-glycans in mediating proteolysis.

A multifunctional fluorescence sensor is an important analytical method for detecting water quality. Herein, PCBH-FS, a fluorescence sensor, is first constructed by dispersing a new compound PCBH in THF-H2O (fw 60%, v/v). PCBH-FS exhibits a distinct red-shifted emission from 405 to 475 nm and a "turn-on" fluorescence response to Fe3+ and Al3+ in the pH range of 5-9, and PCBH-FS exhibits a good fluorescence response to H+ in the pH range from 1 to 5. The Al3+-PCBH system can be used for F- detection, while the Al3+-PCBH and Fe3+-PCBH systems can be used for sequential AcO- detection in THF/H2O mixed media. The binding ratio and the possible sensing mechanism between cations and PCBH molecules are discussed clearly. The LOD of the PCBH-FS reaches 0.44 µM, 0.36 µM, 2.02 µM, and 1.45 µM for detecting Fe3+, Al3+, F-, and AcO- in turn. The sensor provides a simple "on-off" & fluorescent-shift co-detection strategy for sequential detection of multiple ions in aqueous solutions.