Analytical Methods最新文献

We present a novel one-step methodology for direct mass spectrometric characterization of sulfated non-saccharide glycosaminoglycan mimetics in their sodiated form using the high reactivity of trifluorodiazoethane to form hydrophobic and chemically stable esters that facilitates separation and detection in a liquid chromatography–mass spectrometry system. The methodology preserves all sulfates present in the parent molecule, thereby allowing for accurate mass characterization of the per-sulfated molecule.

Laser cleaning is a precise, ‘touch-free’ technique that uses focused laser radiation to remove contaminants from surfaces. It has become increasingly popular in a cultural heritage context due to its ability to target contaminants with minimal damage to underlying materials, particularly where traditional mechanical or chemical cleaning may pose risks to delicate surfaces. However, every cleaning intervention requires a degree of assessment and monitoring, and lasers are no different. This Technical Brief will provide an overview of the physical phenomena behind laser cleaning, give examples of successful cultural heritage applications and list the main pros and cons of the technique.

This study presents a microwave-assisted hydrolysis (MAH) method for accurately determining the molar mass of functional methacrylic polymers and their protein conjugates synthesized via controlled/living polymerization by a grafting from approach. By cleaving ester side chains, MAH converts polymers into linear poly(methacrylic acid) (PMAA), enabling precise molar mass analysis through aqueous size-exclusion chromatography (ASEC). The method is applied to polyglycerol methacrylate (PGMA), polyethylene glycol methacrylate (P(PEGMA)), and lysozyme–PGMA conjugates, with hydrolysis kinetics evaluated under both conventional and microwave heating. Notably, P(PEGMA) exhibits strong resistance to base-catalyzed hydrolysis due to PEG stabilization; however, microwave irradiation significantly improves conversion, achieving results infeasible with standard heating. Characterization by ¹H-NMR, FTIR, and SEC confirms successful hydrolysis and accurate molar mass determination. Calibration using PGMA standards further enhances analytical reliability. The MAH–ASEC approach proves robust, scalable, and broadly applicable, offering a valuable tool for the physicochemical characterization of complex polymeric conjugate systems, particularly in biomedical and materials science contexts.

Scanning ion conductance microscopy (SICM) has emerged as a high-resolution, non-invasive scanning probe technique for studying living cells under physiological conditions and keeping cells intact during measurements using a nanosize-tip glass pipette. Recent advances have established SICM as a universal platform for quantifying the mechanical properties of single living cells, which are increasingly recognized as crucial for cell function and disease progression. Two approaches, based on active pressure-induced deformation or intrinsic cellular forces, offer a tunable indentation force and spatial resolution. SICM can map the mechanical properties of living cells with high resolution and perform combined imaging with other methods such as confocal microscopy or traction force microscopy. SICM has its niche in drug in vitro efficacy monitoring; it gives unique insights into nanobiomechanics of tumor, blood, neuronal and muscle cells and 3D organoids. SICM is poised to become an acute tool for mechanobiology and drug efficacy studies at the nanoscale.

Benvitimod is a non-steroidal tyrosine protein kinase inhibitor commonly used to treat psoriasis. However, it can cause adverse reactions such as contact dermatitis and itching, which can seriously impact consumer health. This study involved designing and synthesising a novel fluorescent labeling reagent, 2-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)oxy)benzoic acid (NBD-SA). This reagent is used to detect benvidimod in cosmetics using high-performance liquid chromatography with fluorescence. With the help of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride/4-dimethylaminopyridine catalysts, NBD-SA can react at 45 °C within an hour, thus providing a quick and effective labeling method for benvitimod. The resulting derivative exhibits remarkable stability and fluorescence properties. The maximum excitation wavelength is 461.96 nm, and the emission wavelength is 578.97 nm. Four cosmetic formulations were completely separated by using a CAPCELL PAK C18 column and gradient elution. Under the optimum conditions, the standard curve shows a good linearity with a determination coefficient of r² = 0.9999. The LOD and LOQ were 0.04 ng mL⁻¹ and 0.11 ng mL⁻¹, respectively. Thus, NBD-SA was successfully used to detect benvitimod that had been illegally added to cosmetics.

The early diagnosis and postoperative monitoring of ovarian cancer rely significantly on the sensitive detection of antigen CA12-5. In this work, a photoelectrochemical immunosensor was developed for the detection of CA12-5, utilizing a CdS/SrTiO₃ heterojunction as the photoactive matrix and NiCo₂O₄ as a quencher probe. The Z-type heterojunction promotes the separation of photogenerated electrons and holes, suppresses the recombination of charge carriers, and thereby significantly enhances the initial photocurrent response. Furthermore, the introduced NiCo₂O₄ quencher generates steric hindrance and competes effectively with the photosensitive material for light absorption, leading to a reduction in the photocurrent signal. This quenching effect greatly enhances the detection sensitivity for CA12-5. The fabricated immunosensor exhibited excellent selectivity and stability under optimal conditions, achieving a wide linear detection range from 5 pg mL⁻¹ to 50 ng mL⁻¹ and a low detection limit of 1.3 pg mL⁻¹.

Florfenicol (FF), a broad-spectrum antibacterial agent widely used in livestock and poultry farming, has raised significant food safety concerns due to the accumulation of its residues in animal-derived products (e.g., eggs), posing potential threats to human health. Herein, we developed a novel aptamer-CRISPR/Cas12a biosensor for the rapid and sensitive detection of FF. The biosensor employs streptavidin-modified magnetic beads (SA-MBs) as a solid carrier to achieve efficient enrichment of FF-specific aptamers (APT), while integrating the dual advantages of the APT's high-specificity target recognition and the CRISPR/Cas12a system's powerful signal amplification capability. The detection mechanism is based on a competitive displacement: APT pre-hybridizes with its complementary strand (APT-c) to form stable duplexes. The presence of FF triggers the release of APT-c from APT, and the liberated APT-c then activates the trans-cleavage activity of the CRISPR/Cas12a system. This process converts the small-molecule FF into a CRISPR/Cas12a-detectable nucleic acid signal and enables quantitative FF detection. Under optimized conditions, the biosensor demonstrated a linear detection range of 10 nM to 100 µM for FF (R² = 0.9907) and a limit of detection (LOD) of 1.41 nM. The accuracy and practicality were confirmed through spiked recovery experiments in egg samples, yielding recoveries between 97.1% and 100.8%. Furthermore, the modular design of this platform allows its easy adaptation for detecting other antibiotics simply by replacing the specific APT and its corresponding APT-c, highlighting its considerable potential for broad applications in food safety monitoring.

Accurate determination of vismodegib (VISMO), a Hedgehog pathway inhibitor approved for the management of basal cell carcinoma and other malignancies, is essential for pharmacokinetic assessment, dose optimization, and therapeutic drug monitoring. In this work, a novel green-emitting “turn-off” fluorometric probe based on nitrogen-doped carbon dots (G-N@CDs) was designed and optimized for the ultrasensitive and selective determination of VISMO in biological matrices. The fluorescence quenching behavior of the probe was predominantly governed by a synergistic combination of the inner filter effect and static quenching mechanisms, indicative of strong ground-state complexation between VISMO and surface functional groups of the G-N@CDs. Under optimized conditions, the system exhibited a broad dynamic linear response from 0 to 340 µM, with an exceptionally low detection limit of 0.4 nM (S/N = 3). The probe demonstrated a rapid signal response within one minute, outstanding selectivity against structurally related antineoplastic agents and common biological interferents, and excellent analytical precision with recoveries ranging from 97.6% to 103.5% and RSD values below 3.69%. Validation in human serum and urine samples confirmed the method's applicability for real-sample analysis, showing excellent agreement with UPLC results. The proposed G-N@CDs system was further employed for pharmacokinetic profiling of VISMO following oral administration, providing accurate concentration–time data that underscore its potential as a robust and cost-effective alternative to conventional chromatographic assays.

Silk fibroin (SF) is a key biomarker for ancient silk artifacts. The rapid and sensitive detection of SF is therefore essential for their compositional analysis and preservation. In this research, an anti-SF monoclonal antibody (anti-SF mAb) was conjugated with an Au^DTNB@Ag nanocore–shell structure to form a highly effective SERS immunoassay probe, and a surface-enhanced Raman scattering (SERS) assisted immunochromatographic assay (ICA) was developed for the detection of silk residues in artifacts. The visual limit of detection (vLOD) is 40 ng mL⁻¹ while the instrumental limit of detection (iLOD) is 3.96 ng/mL⁻¹ with a wide linear detection range (5–100 ng mL⁻¹) as determined through Raman spectroscopy. The assay exhibited high specificity against interfering proteins and demonstrated consistent inter-batch reproducibility. When detecting real cultural relic samples, the immunochromatographic strip assay showed high accuracy and reliability, which was validated by indirect enzyme-linked immunosorbent assay (ELISA). Considering its high sensitivity, rapid analysis, and portability, the SERS ICA may provide a technologically advanced strategy for the on-site screening of silk residues in archaeological and museological contexts.

The treatment of wastewater containing organic dyes is an urgent environmental challenge, necessitating the development of advanced functional adsorbents. In this study, three covalent organic frameworks (COFs) with tailored pore sizes were synthesized from benzotrithiophene tricarboxaldehyde and different diamine linkers—benzidine, naphthalene-1,4-diamine, and p-phenylenediamine. These COFs were grown in situ onto UiO-66-NH₂ to construct core–shell MOF@COF composites. The materials were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Their adsorption performance toward Congo Red (CR), Rhodamine B (RB), and Malachite Green (MG) was systematically evaluated to clarify the influence of COF building units. The composites retained the chemical stability and hydrophobicity of the COF shell while overcoming the instability typical of pristine MOFs. Among them, UiO-66-NH₂@BTT–BZ-COF1 exhibited the highest adsorption capacities—2228.6 mg g⁻¹ for MG, 2037.2 mg g⁻¹ for RB, and 1503.7 mg g⁻¹ for CR—and could be reused for at least five cycles, demonstrating promising potential for dye removal applications.