Microchemical Journal最新文献

Accurate sensing of small biomolecules from complex biofluid media remains a challenge due to adverse interaction of metallic salts and other biofluid components. L-cystine is the most important biomarker for the disease cystinuria. Recognition of L-cystine in urine is thus fundamental for the timely detection of cystinuria and related chronic kidney disease (CKD). Poor solubility of L-cystine offer limits to design suitable sensors. Herein, we report the synthesis of thioglycolated-β-CD (TG-β-CD) anchored silver nanoparticles (AgNP) as a potential receptor (TG-β-CD$\supset$AgNP) for the effective optical recognition and quantification of L-cystine through UV–Vis and SERS (surface enhanced Raman spectroscopy) spectroscopic fingerprinting and suitable colourimetric naked-eye detection of L-cystine by indicator displacement assay. Methyl orange (Met-O) indicator was precomplexed with the receptor to generate the probe solution (Met-O@TG-β-CD$\supset$AgNP). Indicator has been exchanged from Met-O@TG-β-CD$\supset$AgNP by the addition of L-cystine, with an instantaneous visible colour change from yellow to red. The method is tolerable to other interfering abundant ions and biomolecules. Based on the innovative sensing assay a cellulose paper-dye test strip is developed for point-of-care detection and quantification of the biomarker. Structures of TG-β-CD, TG-β-CD$\supset$AgNP and Met-O@TG-β-CD$\supset$AgNP were elucidated by UV–Vis, FT-IR, PXRD, ¹H NMR, etc. spectroscopy. Scanning electron microscopy (SEM) was used to examine the morphology of TG-β-CD, AgNP and TG-β-CD$\supset$AgNP. The chemical changes during the assay were evaluated by conductance, UV–Vis and SERS. The competitive displacement of the indicator and UV turn-on at ppm level analyte concentration made the process compatible for day-to-day point-of-care units.

The need for a fast and reliable platform for the detection of pathogens in point-of-care (POC) applications is increasing day by day. Molecular detection of pathogens is made possible by a good DNA isolation method, which allows for efficient and pure extraction from the cell. To address this need, our work presents a new lateral flow platform based on UV ozone-treated glass fiber pads for high-throughput DNA isolation from very low volumes of bacterial samples. The platform we developed mainly consists of UV ozone-treated glass fiber, which serves as the essential component binding DNA, and a cellulose-based absorbent pad acting as a reservoir for washing buffers and undesired substances from bacterial cells. UV ozone treatment increased the DNA recovery efficiency of glass fiber by 2.5 times compared to untreated glass fiber. qPCR results confirmed the isolation of pure DNA from both gram-negative and gram-positive bacteria samples performed on the developed platform. For five different bacteria concentrations (10–10⁹ cfu/mL), a good linearity between Cq values and bacteria concentrations was obtained. A minimum concentration of 10 cfu/mL could be detected for both bacterial samples of 10 µL. The developed DNA extraction platform was also integrated with a portable heater for the LAMP-based detection application. We successfully demonstrated that the proposed extraction platform, combined with the colorimetric LAMP-based system, can detect Staphylococcus aureus bacteria spiked in whole blood samples in under one hour, including both extraction and detection processes. Our simplified paper-based platform will be a good alternative for the DNA extraction and molecular detection of pathogens without the need for complex laboratory equipment in POC applications.

Mitochondrial membrane potential (ΔΨ_m) participated in important physiological processes such as ATP synthesis, ion exchange, and plays an important role in maintaining normal life activities of cells. Herein, we synthesized a fluorescent probe EDXB (3-ethyl-2-(2-(6-methoxy-2,3-dihydro-1H-xanthen-4-yl) vinyl) benzothiazol-3-ium iodide) with positive charge, which targets mitochondria by electrostatic attraction. The probe has twisted intramolecular charge transfer (TICT) characteristics, resulting in near-infrared fluorescence emission enhanced with the increase of viscosity, when the probe falls off from the mitochondrial membrane to the low-viscosity cytoplasmic aqueous phase, the fluorescence emission intensity is weakened. Therefore, the EDXB exhibited favorable targeting. In addition, EDXB also has good anti-bleaching and pH stability, which enables it to accurately feedback the change of ΔΨ_m. In the experiment, the intracellular imaging of EDXB certificated mitochondrial depolarization (decrease of ΔΨ_m) during various cell injury events including cell inflammation, apoptosis and mitophagy. We expect EDXB to be a useful tool for the analysis of ΔΨ_m changes.

The presence of Acidovorax citrulli (Ac), the etiological agent responsible for bacterial fruit blotch (BFB), exerts a profound impact on the growth and development of cucurbit plants. Therefore, it is imperative to promptly detect Ac to effectively mitigate the widespread dissemination of this disease among cucurbit crops. The present study describes the development of a novel label-free immunochromatographic strip (ICTS) sensor for the detection of Ac in cucurbit samples. This was achieved by utilizing 4’,4’’’,4’’’’’,4’’’’’’’-(ethene-1,1,2,2-tetrayl) tetrabiphenyl-4-carboxylic acid (TCBPE) carboxyl activation product (CA-TCBPE) as a fluorescent probe. The CA-TCBPE@Ac complex is captured at the detection site through the immobilization of a monoclonal antibody monoclonal antibody (mAb) targeting Ac in this sensor. Under the excitation of 365 nm ultraviolet (UV) light, the detection of Ac in the concentration range of 10⁵-10⁸ CFU/mL was successfully achieved, with a visual detection limit of 10⁵ CFU/mL. The accuracy of the sensor was further validated through experimentation with real samples, including watermelon, cantaloupe, cucumber, and zucchini. This study presents the pioneering development of a label-free ICTS sensor, utilizing TCBPE material markers, for rapid and sensitive detection of Ac. This innovative approach offers a robust solution for the swift detecting of Ac in cucurbits and other samples, thereby holding great promise for future applications.

We developed a new method to produce fiber electrodes from single-walled carbon nanotube (SWCNT) films, which can be employed as a novel sensing platform for electrochemical investigations and analysis. By assembling SWCNT bundles in the form of a strong free-standing fiber with almost entire surface accessible to an analyte, we are able to avoid the interference of substrate and improve detection efficiency. We examined the influence of physical, chemical and electrochemical pretreatments of the new electrode SWCNT material on its properties. Transmission and scanning electron microscopy, Raman spectroscopy and cyclic voltammetry were used to characterize the SWCNT fibers. The modification of the SWCNT fiber electrode with gold nanoparticles provides the necessary analytical characteristics including high repeatability and sensitivity and low detection limit (1.3 – 2.1 μg L^-1) for arsenic determination by anodic stripping voltammetry. Arsenic detection parameters such as deposition potential, deposition time and scan rate were optimized. Linear responses were found in concentration ranges from 3 to 210 μg L^-1 and 7 to 125 μg L^-1 for gold modified SWCNT fiber sensors (the SWCNTs were synthesized using CO or ethanol as precursors) at a relatively low deposition time of 60 s. The developed Au-SWCNT sensors allow rapid As determination in real samples and exhibit high durability and long service life.

Waste PET is utilized to produce recycled PET (rPET) through bottle-to-bottle recycling in order to reduce environmental pollution. However, non-intentionally added substances (NIAS) may be generated during rPET production, potentially posing a threat to food safety. In this study, a non-target screening of 13 batches with a total of 39 rPET samples was performed using GC-QTOF-MS and 240 compounds were tentatively identified. It was worth noting that the detection of phthalate esters in rPET from China, such as bis(2-ethylhexyl) phthalate, exhibits a higher diversity (17 different types) and frequency (7.8 %–100 %) in comparison with related studies. Subsequently, based on the principles for selection of surrogates used in challenge test, seven molecular descriptors were selected as variables for compound characterization, followed by principal component analysis (PCA) for representation. Based on this analysis and referencing the EFSA and FDA surrogate suggestion lists, eight surrogates were proposed for China, namely chlorobenzene, toluene, benzophenone, bis(2-ethylhexyl) terephthalate, methyl salicylate, methyl stearate, 1-phenyldecane and phenylcyclohexane. High-throughput detection methods were developed for each surrogate with the regression correlation coefficients over 0.999, spiked recoveries ranging from 99.3-107.5 %, LODs of 0.003–2.192 ng/mL, LOQs of 0.009–7.306 ng/mL, RSD of 0.71–4.23 %, respectively. This research provides foundational data and methodological support for the evaluation of rPET challenge testing in China, offering technical support for subsequent safety assessments of rPET.

Dermestidae is a group of beetles common in forensic and storage research. The weathering patterns of their exuviae may have potential value for the estimation of the postmortem interval (PMI) in forensic entomology, burial time in forensic taphonomy and invasion time in storage containers. However, no relevant research has been done. In this study, a large number of final instar Dermestid exuviae were kept at 16 °C, 25 °C, 34 °C and indoor variable temperatures, allowing them to naturally weather for 90 days. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and gas chromatography-mass spectrometry (GC–MS) were used to detect 13 time points during this period. The corresponding spectra and peak areas of n-alkanes were obtained to explore whether some functional groups or n-alkanes undergo temporal changes in weathering. The results showed that 90 days of weathering did not significantly change the chromatographic peak area or the corresponding spectral absorption peaks of n-alkanes in Dermestid exuviae, while the amides showed an attenuation trend. The accuracy of the training set and test set of the established partial least square-discriminant analysis (PLS-DA) models were 89.04 % and 75.54 %, respectively, and that of the random forest (RF) models were 100 % and 75.00 %, respectively, achieving good classification results. This indicates that the weathering patterns of Dermestid exuviae have value for estimating the PMI. This study is the first to investigate the weathering of necrophagous beetle exuviae with the aim of estimating the PMI. In the future, additional research should be performed under outdoor conditions or a longer weathering time.

Antioxidants are commonly found in both natural and synthetic forms. Recent years have witnessed significant efforts directed towards the identification of natural antioxidants. This review focuses on the recent advancements in electrochemical sensors constructed using deep eutectic solvents for electrode modification, emphasizing their role in detecting natural antioxidants such as ascorbic acid, phenolic acids, flavonoids, tryptophan, and citric acid. The term ’green’ denotes the progression of electrochemical sensing platforms employing biodegradable and sustainable materials, particularly those utilizing green solvents, e.g., deep eutectic solvents (DES). The electrochemical performance of these green sensors and their associated benefits, including biodegradability, non-toxicity, sustainability, and low cost, are discussed. Furthermore, the review outlines the limitations of existing DES-based modified electrode sensing technology, current development trends, and the potential applications for various natural antioxidant substances. The objective of this review is to offer insights for researchers engaged in the field of electrochemical sensors DES-modified electrodes.

Located in the epidermis, the stratum corneum is the most superficial layer of the skin, acting as a barrier against aggression from the external environment, preventing dehydration, and maintaining the water balance of the skin. The stratum corneum contains the Natural Hydration Factor (NMF), a mixture of hygroscopic molecules derived from filaggrin. The NMF includes 2-pyrrolidone-5-carboxylic acid (PCA), urocanic acid (UCA), and histidine (His), target biomarkers that were extracted by tape-stripping from the stratum corneum of participants for quantification in HPLC-PDA. By extracting the stratum corneum, we developed a protocol to optimize, through audience definition, the quantification of NMF biomarkers. Chromatographic analysis was performed using a YMC-Triart C18 chromatographic column, with a gradient elution of mobile phase composed of triethylammonium phosphate and acetonitrile mixture, and a photodiode array detector. HPLC-PDA procedure was selective, linear (in the range from 0.2 to 5.0 µg/mL), accurate (recovery from 92.7 to 115.1 %), precise (RSD from 0.3 to 12.1 %), and with proper detection and quantification limits. The measurement uncertainty was evaluated from validation data, with combined standard uncertainty values of 0.025–0.12 µg/mL (2.1–5.6 %), 0.004–0.28 µg/mL (2.4–12.6 %), and 0.016–0.16 µg/mL (3.2–7.9 %) for His, PCA, and UCA, respectively. Statistical analyses were performed using Monte Carlo simulation and the Mann-Whitney test, as our results were not homoscedastic and deviated from normality. The results indicate that the best audience for quantifying biomarkers were participants up to 35 years old, with all phototypes, and, preferably, female.

Traditionally, various techniques like water, vegetable oil, and solvent extraction are used to extract annatto pigments, a natural coloring agent derived from the Bixa orellana L. shrub. These traditional extraction methods can be time consuming and yield minimal pigment concentrations. This study explores an innovative approach to extract the maximum pigments from the annatto seed using supercritical fluid extraction (SFE). Fresh, extracted aqueous, and peeled samples of annatto powder were used at different temperatures (40, 45, and 50 °C) using different solvents of ethanol, methanol, and ethyl acetate with 99 % purity. The optimal extraction condition in supercritical fluid extraction is obtained with an aqueous sample treated with methanol solvent at 45 °C that yields 4.62 % norbixin, 2.49 % bixin, and a hue angle of 24.85⁰, achieving a high desirability value (0.949). Response surface method (RSM) was used to optimize the extraction procedure to obtain a higher yield of annatto pigments. In addition, for optimized conditions, the total phenols and antioxidants assay yielded 3.8 mg GAE/g and 51 % inhibition. HPLC analysis confirmed norbixin in the extracts obtained with a retention time of 38.40 min. This method offers a significant boost in pigment extraction efficiency, but also minimizes processing time. These combined advantages position it as a potentially superior approach for producing annatto pigments with enhanced concentration and purity.