Recent progress of metal-organic framework-based nanozymes with oxidoreductase-like activity.

Nanozymes, a class of synthetic nanomaterials possessing enzymatic catalytic properties, exhibit distinct advantages such as exceptional stability and cost-effectiveness. Among them, metal-organic framework (MOF)-based nanozymes have garnered significant attention due to their large specific surface area, tunable pore size and uniform structure. MOFs are porous crystalline materials bridged by inorganic metal ions/clusters and organic ligands, which hold immense potential in the fields of catalysis, sensors and drug carriers. The combination of MOFs with diverse nanomaterials gives rise to various types of MOF-based nanozyme, encompassing original MOFs, MOF-based nanozymes with chemical modifications, MOF-based composites and MOF derivatives. It is worth mentioning that the metal ions and organic ligands in MOFs are perfectly suited for designing oxidoreductase-like nanozymes. In this review, we intend to provide an overview of recent trends and progress in MOF-based nanozymes with oxidoreductase-like activity. Furthermore, the current obstacles and prospective outlook of MOF-based nanozymes are proposed and briefly discussed. This comprehensive analysis aims to facilitate progress in the development of novel MOF-based nanozymes with oxidoreductase-like activity while serving as a valuable reference for scientists engaged in related disciplines.

Recent advances in colorimetric sensors based on nanozymes with peroxidase-like activity.

Nanozymes have been widely used to construct colorimetric sensors due to their advantages of cost-effectiveness, high stability, good biocompatibility, and ease of modification. The emergence of nanozymes greatly enhanced the detection sensitivity and stability of the colorimetric sensing platform. Recent significant research has focused on designing various sensors based on nanozymes with peroxidase-like activity for colorimetric analysis. However, with the deepening of research, nanozymes with peroxidase-like activity has also exposed some problems, such as weak affinity and low catalytic activity. In view of the above issues, existing investigations have shown that the catalytic properties of nanozymes can be improved by adding surface modification and changing the structure of nanomaterials. In this review, we summarize the recent trends and advances of colorimetric sensors based on several typical nanozymes with peroxidase-like activities, including noble metals, metal oxides, metal sulfides/metal selenides, and carbon and metal-organic frameworks (MOF). Finally, the current challenges and prospects of colorimetric sensors based on nanozymes with peroxidase-like activity are summarized and discussed to provide a reference for researchers in related fields.

[Advances in chiral separation and analysis by capillary electrophoresis-mass spectrometry].

Most drugs used to treat diseases are chiral compounds. Drug enantiomers possess similar physical and chemical properties but may feature distinct pharmacological activities. Drug enantiomers may also exhibit different or even opposite functionalities for metabolism, in terms of the metabolic rate and toxicity in the body. Therefore, it is imperative to analyze, separate, and purify the enantiomers of drugs. The separation of chiral compounds is essential for drug research and development. It is also of significance in various fields including biological environments, food, and medicine. Various highly selective and sensitive methods have been developed for the quantitative and qualitative analyses of chiral compounds. A typically employed technique is high performance liquid chromatography-mass spectrometry (HPLC-MS). While HPLC-MS offers high sensitivity and reproducibility, it requires expensive chiral columns and MS-compatible mobile phases for the chromatographic column. Further, the column efficiency and resolution capacity in chiral chromatography packing require improvement. Recent progress has shown that capillary electrophoresis-mass spectrometry (CE-MS) has broad applications in chiral analysis. As a well-established analytical technique, CE-MS combines the highly efficient separation technique of CE with the highly sensitive detection technique of MS. Thus, it offers many essential advantages for analysis. For example, CE-MS has a high separation efficiency and requires very low amounts of samples and reagents. It can also achieve sensitive and selective determination, and the obtained diversified separation modes can be used for different samples. Therefore, CE-MS has proved to be important in analytical chemistry, especially in proteomics and metabolomics. CE can also exhibit excellent performance in chiral separation. Hence, combined with the sensitive detection technique of MS, CE-MS would be ideal for chiral analysis. Chiral CE-MS can provide a wide range of qualitative information on samples simultaneously in a single run, including the migration time, relative molecular mass, and ionic fragments. It addresses the challenges associated with identifying unknown chiral compounds in actual samples (including chiral compounds without UV absorption groups or fluorescence groups). The high-throughput analysis of multiple groups of chiral enantiomers can be achieved while mitigating the matrix effect of biological samples. In the last ten years, high performance chiral analysis strategies based on different CE-MS modes have been developed. These include electrokinetic chromatography-mass spectrometry (EKC-MS), micellar electrokinetic chromatography-mass spectrometry (MEKC-MS), and capillary electrochromatography-mass spectrometry (CEC-MS). CE-MS has been successfully applied in chiral analysis in various fields such as medicine, biology, food, and environmental science. CE-MS is promising in the chiral analysis of drugs, especially for drug development and drug quality control, as well as pharmacokinetics and pharmacodynamics research. Recent studies have focused on the development of MS-friendly and highly selective chiral analytical methods, which will broaden the application of CE-MS. In CEC-MS chiral analysis, more attention has been paid to developing novel capillary chiral stationary phases for monolithic or packed columns. Because of the diversity of chiral selectors for EKC-MS and MEKC-MS, the chiral analysis of drugs using these techniques has attracted intense research interest. Moreover, functional nanoparticles have been employed to increase the surface area of the CEC columns for enhancing the efficiency of chiral analysis. The chiral separation and analysis of miniaturized microchip equipment via CE-MS has also been explored, but remains to be widely used in practical applications. The purpose of this review is to provide insights that would aid in broadening the applications of CE-MS to chiral analysis. In this review, we primarily summarize research progress on the application of CE-MS to chiral analysis, based on the literature published during the years 2011-2021. Chiral selectors (e. g., modified cyclodextrin and polymer surfactants) and their reported applications in CE-MS are presented. The determination results for drug enantiomers using different CE-MS modes are compared. The application of CE-MS in other research fields is also presented, along with the advantages and limitations of different CE-MS methods.

A photonic crystal fiber-based fluorescence sensor for simultaneous and sensitive detection of lactic acid enantiomers.

A photonic crystal fiber (PCF)-based fluorescence sensor is developed for rapid and sensitive detection of lactic acid (LA) enantiomers in serum samples. The sensor is fabricated by chemical binding dual enzymes on the inner surface of the PCF with numerous pore structures and a large specific surface area, which is suitable to be utilized as an enzymatic reaction carrier. To achieve simultaneous detection of L-LA and D-LA, the PCF with an aldehyde-activated surface is cut into two separate pieces, one of which is coated with L-LDH/GPT enzymes and the other with D-LDH/GPT enzymes. By being connected and carefully aligned to each other by a suitable sleeve tube connector, the responses of both L-LA and D-LA sensors are determined by laser-induced flourescence (LIF) detection. With the aid of enzyme-linked catalytic reactions, the proposed PCF sensor can greatly improve the sensitivity and analysis speed for the detection of LA enantiomers. The PCF sensor exhibits a low limit of detection of 9.5 µM and 0.8 µM, and a wide linear range of 25-2000 µM and 2-400 µM for L-LA and D-LA, respectively. The sensor has been successfully applied to accurate determination of LA enantiomers in human serum with satisfactory reproducibility and stability. It is indicated that the present PCF sensors would be used as an attractive analytical platform for quantitative detection of trace-amount LA enantiomers in real biological samples, and thus would play a role in disease diagnosis and clinical monitoring in point-of-care testing.

Ursolic Acid Targets Glucosyltransferase and Inhibits Its Activity to Prevent Streptococcus mutans Biofilm Formation.

Streptococcus mutans (S. mutans), the prime pathogen of dental caries, can secrete glucosyltransferases (GTFs) to synthesize extracellular polysaccharides (EPSs), which are the virulence determinants of cariogenic biofilms. Ursolic acid, a type of pentacyclic triterpene natural compound, has shown potential antibiofilm effects on S. mutans. To investigate the mechanisms of ursolic acid-mediated inhibition of S. mutans biofilm formation, we first demonstrated that ursolic acid could decrease the viability and structural integrity of biofilms, as evidenced by XTT, crystal violet, and live/dead staining assays. Then, we further revealed that ursolic acid could compete with the inherent substrate to occupy the catalytic center of GTFs to inhibit EPS formation, and this was confirmed by GTF activity assays, computer simulations, site-directed mutagenesis, and capillary electrophoresis (CE). In conclusion, ursolic acid can decrease bacterial viability and prevent S. mutans biofilm formation by binding and inhibiting the activity of GTFs.

Portable and automated analyzer for rapid and high precision in vitro dissolution of drugs.

We developed a novel portable and automated dissolution test analyzer for rapid and high precision in vitro dissolution testing of drugs. The analyzer consists of a flow-through-cell drug dissolution system, an automated sequential sampling system, a high-speed capillary electrophoresis (HSCE) system, and a data acquisition system. Combining the high-temporal resolution flow-gating sampling approach with HSCE, which has outstanding advantages of efficient separation and resolution, the analyzer can achieve rapid analysis and exhibits the ability in miniaturization for on-site assessment of different active pharmaceutical ingredients. To integrate the flow-through-cell dissolution system with HSCE, a specially designed flow-gating-injection (FGI) interface was employed. The performance of the analyzer was investigated by analyzing the dissolution of immediate-release drugs including single dose (amoxicillin dispersible tablets) and fixed dose combination (amoxicillin and clavulanate potassium) drug tablets with the high-temporal resolutions of 12 s and 20 s, respectively. The dissolution profiles of different active pharmaceutical ingredients could be simultaneously and automatically monitored with high repeatability and accuracy. The analyzer was successfully utilized for the pharmaceutical quality control and bio-relevant dissolution testing, as well as in vivo-in vitro correlation analysis. Our portable analyzer is miniaturized, convenient and of low-cost, and will provide a valuable tool for dissolution testing in pharmaceutical research and development.

High-throughput monitoring of biomass conversion reaction with automatic time-resolved analysis.

Reactions of biomass conversions are of great importance in fine chemistry for substantial development. While numerous studies have been performed to search for functional materials to catalyze biomass conversions, a robust and high-throughput analytical method is rather limited, which may hamper further integration and automation of the reactions. Here we propose an automatic and sequential method for the investigation of glucose conversion. By combining sequential sample injection and high-speed capillary electrophoresis (HSCE) techniques, we can monitor the glucose conversion from the beginning toward the end with a good temporal resolution. The HSCE assays are performed using short capillaries (effective length of 10 cm, i.d./o.d. of 50 µm/365 µm), and the analytes are separated at an electric field of 467 V/cm and are detected by UV-absorption at 200 nm with mixed 0.2 mM CTAB, 10 mM borate, 20 mM sorbic acid (pH 12.2) as the background electrolyte. All compounds involved in the reaction, including all products (fructose, 5-hydroxymethylfurfural, formic acid and levulinic acid) and the remaining substrate glucose, are efficiently separated and simultaneously detected from just one analysis with a temporal resolution of one minute. The method exhibits high-resolution separation, a wide linear range with limit-of-detection down to µg/mL-level, as well as excellent repeatability in sequential analysis. It is indicated that the proposed method is of great value in the analysis of complicated biomass conversion and could be potentially applied in various catalytic chemical reactions.

Portable and automated analyzer for rapid and high precision in vitro dissolution of drugs / 药物分析学报

We developed a novel portable and automated dissolution test analyzer for rapid and high precision in vitro dissolution testing of drugs.The analyzer consists of a flow-through-cell drug dissolution system,an automated sequential sampling system,a high-speed capillary electrophoresis (HSCE) system,and a data acquisition system.Combining the high-temporal resolution flow-gating sampling approach with HSCE,which has outstanding advantages of efficient separation and resolution,the analyzer can achieve rapid analysis and exhibits the ability in miniaturization for on-site assessment of different active pharmaceutical ingredients.To integrate the flow-through-cell dissolution system with HSCE,a specially designed flow-gating-injection (FGI) interface was employed.The performance of the analyzer was investigated by analyzing the dissolution of immediate-release drugs including single dose (amoxicillin dispersible tablets) and fixed dose combination (amoxicillin and clavulanate potassium) drug tablets with the high-temporal resolutions of 12 s and 20 s,respectively.The dissolution profiles of different active pharmaceutical ingredients could be simultaneously and automatically monitored with high repeatability and accuracy.The analyzer was successfully utilized for the pharmaceutical quality control and bio-relevant dissolution testing,as well as in vivo-in vitro correlation analysis.Our portable analyzer is miniaturized,convenient and of low-cost,and will provide a valuable tool for dissolution testing in pharmaceutical research and development.

On-line dissolution analysis of multiple drugs encapsulated in electrospun nanofibers.

Electrospun nanofiber is a very attractive material which can be used as the support to form multiple-drug dosage. Understanding the dissolution process of different active drug ingredients released from electrospun fibers is of great importance to control and evaluate the quality of medicated nanofibers. Here we present the first study of on-line automatic analysis of dissolution of multiple drugs in electrospun fiber mats. Single-needle electrospinning technology is utilized to combine polymers, hydrophilic polyvinylpyrrolidone (PVP) and hydrophobic polycaprolactone (PCL) as carrier to load three poorly water-soluble non-steroidal anti-inflammatory drugs (paracetamol, nimesulide, and ibuprofen). The loading of the drugs in PVP/PCL electrospun fibers are characterized by various techniques, including scanning electron microscopy, X-ray diffraction, Fourier infrared spectroscopy and differential scanning calorimetry. The in vitro dissolution is investigated by our home-made portable analyzer, which can simultaneously on-line determine multiple drugs released from the nanofibers by a single step. The analysis shows a wide linear detection range of the drugs with limit-of-detection (LOD) down to µg/mL-level. The dissolution profiles of three ingredients in nanofibers can be monitored every thirty seconds from the beginning to the end in the entire dissolution process from only one HSCE run. The kinetic information of the dissolution, including the dissolution curve, characteristic dissolution time and dissolution efficiency, is obtained and evaluated for different dissolution media, drug loading content and the ratio of PVP/PCL. Our study provides a promising method for rapid and accurate dissolution testing of nanofiber-based drugs, and would extend the applications of separation techniques in pharmaceutical analysis.

Automatic Dissolution Testing with High-Temporal Resolution for Both Immediate-Release and Fixed-Combination Drug Tablets.

Dissolution testing plays many important roles throughout the pharmaceutical industry, from the research and development of drug products to the control and evaluation of drug quality. However, it is a challenging task to perform both high-efficient separation and high-temporal detection to achieve accurate dissolution profile of each active ingredient dissolved from a drug tablet. In our study, we report a novel non-manual-operation method for performing the automatic dissolution testing of drug tablets, by combining a program-controlled sequential analysis and high-speed capillary electrophoresis for efficient separation of active ingredients. The feasibility of the method for dissolution testing of real drug tablets as well as the performance of the proposed system has been demonstrated. The accuracy of drug dissolution testing is ensured by the excellent repeatability of the sequential analysis, as well as the similarity of the evaluation of dissolution testing. Our study show that the proposed method is capable to achieve simultaneous dissolution testing of multiple ingredients, and the matrix interferences can be avoided. Therefore it is of potential valuable applications in various fields of pharmaceutical research and drug regulation.