High Throughput and Noninvasive Exosomal PD-L1 Detection for Accurate Immunotherapy Response Prediction via Tim4-Functionalized Magnetic Core-Shell Metal-Organic Frameworks.

Exosomal PD-L1 has been increasingly considered a noninvasive and accurate predictive marker for immunotherapy treatment response. However, the clinical monitoring of exosomal PD-L1 expression is still limited by its complex biological environment as well as the lack of a robust isolation strategy. Here, a Tim4-functionalized magnetic core-shell metal-organic framework (denoted as Fe3O4@SiO2-ILI-01@Tim4) was facilely constructed via layer-by-layer assembly. Owing to the strongly hydrophilic organic ligand of 1,3-bis(4-carboxybutyl)imidazolium bromide (ILI), magnetic Fe3O4@SiO2-ILI-01@Tim4 was endowed with the merits of low nonspecific adsorption and quick, easy, and convenient isolation of exosomes. The capture efficiency of Fe3O4@SiO2-ILI-01@Tim4 reached as high as 90.3 ± 0.5% and the recovery rate for exosomes was up to 93.0 ± 6.1%. The purity of the isolated exosomes was 7.5 times higher than that via the ultracentrifugation (UC) method. By further combination with immunofluorescence assay, high throughput and noninvasive exosomal PD-L1 detection for accurate immunotherapy response prediction was achieved. The prognosis accuracy of the developed Fe3O4@SiO2-ILI-01@Tim4-based strategy reached 85.7%, whereas the prognosis accuracy of the clinical gold standard, the PD-L1 combined positive score (CPS) test, was only 57.1%. Most interestingly, the developed method is especially suitable for those patients receiving false negative results in the CPS test. The proposed Fe3O4@SiO2-ILI-01@Tim4 is a highly efficient and robust technique showing great potential in high throughput and noninvasive exosomal PD-L1 detection for accurately predicting immunotherapy efficacy.

PEG-modified halloysite as a hydrophilic interaction and cation exchange mixed-mode sorbent for solid-phase extraction of biogenic amines in fish samples.

A novel type of PEG-modified halloysite was prepared and used as a hydrophilic interaction and cation exchange mixed-mode sorbent for solid-phase extraction of biogenic amines in fish samples. The eluates were analyzed by high-performance liquid chromatography-ultraviolet detection after the derivatization with benzoyl chloride. The developed sorbent was characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, zeta potential analyzer, and thermo-gravimetric analysis. After the optimization of various parameters influencing the extraction efficiency, the PEG-modified halloysite-based SPE method was evaluated. The adsorption capacities of putrescine, spermine, phenethylamine, and histamine were as high as 9.3, 8.5, 5.7, and 5.6 mg g-1, respectively. Satisfactory reproducibility of sorbent preparation was obtained with within-batch and batch-to-batch relative standard deviations (RSDs) lower than 3.9% and 8.6%, respectively. The biogenic amine spiking recoveries in fish samples ranged from 84.3 to 105.5% with good RSDs lower than 7.8%. Intra-day and inter-day precision, expressed as RSDs, were better than 8.8%. The limits of detection of histamine, putrescine, phenethylamine, and spermine were 9.4, 1.9, 0.5, and 0.9 µg L-1, respectively. This work provides a new hydrophilic interaction and cation exchange mixed-mode sorbent and is successfully applied to the extraction of trace biogenic amines from fish samples.

Design, synthesis and biological activity evaluation of novel covalent S-acylation inhibitors.

In order to obtain diverse S-acylation inhibitors and address the defects of existing S-acylation inhibitors, a series of novel covalent S-acylation inhibitors are designed through synthesis. According to the results of MTT assay, most compounds produce a better anti-proliferation effect on MCF-7, MGC-803 and U937 cell lines than 2-BP. Among them, 8d, 8i, 8j and 10e exert a significant inhibitory effect on MCF-7 cell, with the IC50 values falling below 20 µM. Besides, the toxic effects of some compounds on 3T3 cell line are less significant than 2-BP. According to the results of acyl-biotin exchange (ABE) experiment, most of them could inhibit S-acylation, and 8i performs best in this respect, with the inhibitory rate reaching 89.3% at the concentration of 20 µM. The results of molecular docking show the conjugation of 8i with surrounding amino acids. Additionally, 8i could not only suppress the migration of MCF-7 cell line, but also cause it to stagnate in G0/G1 phase, thus promoting cell apoptosis.

Preparation and chromatographic performance of chiral peptide-based stationary phases for enantiomeric separation.

This study presents the development of three new chiral stationary phases. They are based on silica modified with peptides containing phenylalanine and proline. Successful analyses and characterizations were conducted using Fourier transform infrared spectra, elemental analysis, and thermogravimetric analysis. After this, the enantioselective performance of the three chiral peptide-based columns was evaluated. The evaluation used 11 racemic compounds under normal-phase high performance liquid chromatography mode. Optimized enantiomeric separation conditions were established. Under these conditions, the enantiomers of flurbiprofen and naproxen were successfully separated on CSP-1 column: the separation factor of these was 1.27 and 1.21, respectively. In addition, the reproducibility of the CSP-1 column was also investigated. The results of the investigation illustrated that the stationary phases have good reproducibility (RSD = 0.73%, n = 5).

Label-Free Small Extracellular Vesicles Capturing Strategy for Lung Cancer Diagnosis and Typing Based on a Natural Polyphenol-Metal Three-Dimensional Network.

Small extracellular vesicles (sEVs) have been increasingly recognized as circulating biomarkers and prognosticators for disease diagnosis. However, the clinical applications of sEVs are seriously limited by the lack of a robust and easy scale-up isolation technique. Herein, the feasibility of a polyphenol-metal three-dimensional (3D) network for label-free sEV isolation was explored. As a proof-of-concept, with tannic acid (TA) as the polyphenolic ligand and Fe(III) as the coordinated metal, the TA-Fe(III) 3D network coating mesoporous silica beads (SiO2@BSA@Fe-TA6) was designed and fabricated via a coordination-driven layer-by-layer self-assembly approach. The successful fabrication of SiO2@BSA@Fe-TA6 was validated by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. With the low-cost TA (as low as US$ 0.18/g) as the probe, SiO2@BSA@Fe-TA6 achieved universal capture toward sEVs in different cells and plasma samples. The capture efficiency reached 85.4 ± 1.5%, which is comparable to the antibody-based capture techniques and significantly higher than the ultracentrifugation (UC) method. The purity of sEVs isolated by SiO2@BSA@Fe-TA6 from the H1299 cell culture supernatant was measured as (1.07 ± 0.14) × 1011 particles/µg, which is 3.1 times higher than that via the UC method. Another important superiority of SiO2@BSA@Fe-TA6 is the facile self-assembly approach, which can harvest a yield of up to grams, allowing simultaneous processing of more than 500 plasma samples. The SiO2@BSA@Fe-TA6-based strategy was further successfully employed to distinguish nonsmall cell lung cancer (NSCLC) and small cell lung cancer (SCLC) with an accuracy of 87.1%. The developed SiO2@BSA@Fe-TA6 is a label-free, universal, low cost, and easy scale-up technique for sEV-based liquid biopsy in lung cancer diagnosis and typing.

Anti-Tim4 Grafting Strongly Hydrophilic Metal-Organic Frameworks Immunoaffinity Flake for High-Efficiency Capture and Separation of Exosomes.

Exosomes have become the most ideal analysis target for liquid biopsy since they carry a large amount of genetic materials. The study on exosomes has great significance for cancer diagnosis and prognosis. However, the extremely low concentration renders the development of a robust exosomes enrichment technique, with the merits of low nonspecific cell adhesion, high-capture efficiency, and easy nondestructive release of captured exosomes, of vital significance. We successfully designed and developed a novel Tim4@ILI-01 immunoaffinity flake material. First, a strongly hydrophilic ILI-01 MOFs matrix material was fabricated with cationic ionic liquid 1,3-bis(4-carboxybutyl)imidazolium bromide as the organic ligand. The nonspecific adsorption of the ILI-01 MOFs material was only 0.7% after two washings with a neutral buffer. Moreover, based on the inherent abundant carboxyl groups on the ILI-01 MOFs flake, they can be facilely functionalized with an anti-Tim4 antibody with the bonding efficiency of 82.4%. The capture efficiency of the developed Tim4@ILI-01 immunoaffinity material for exosomes reached 85.2%, which is 5.2 times higher than that via the gold standard ultracentrifugation method. Furthermore, based on the Ca2+-dependent characteristic of the binding between the Tim4@ILI-01 immunoaffinity material and phosphatidylserine (PS) on the surfaces of exosomes, the captured exosomes can be easily released with the addition of a chelating agent under neutral eluent conditions. Thus, the captured exosomes maintained good biological activity. The developed Tim4@ILI-01 immunoaffinity flake was successfully applied for enrichment of exosomes from serums of healthy persons and lung adenocarcinoma patients. The levels of the expressed CD44 gene significantly changed under different stages of lung adenocarcinoma cancer. All these results demonstrate that the Tim4@ILI-01 immunoaffinity flake is a robust enrichment material and has a good potential in practical clinical applications.

Highly Efficient Enrichment of O-GalNAc Glycopeptides by Using Immobilized Metal Ion Affinity Chromatography.

Proteomics analysis of O-GalNAc glycosylation is important for the screening of biomarkers and the assessment of therapeutic responses. However, its analysis still faces challenges due to the poor performance of currently available enrichment methods. In this study, an enrichment method was established on the basis of Ti-IMAC(IV) materials, which could enrich the intact O-GalNAc glycopeptides via both the hydrophilic interaction and affinity interaction. This method enabled nearly 200 intact O-GalNAc glycopeptides identified from only 0.1 µL of human serum. This was nearly 2-fold different from that of the HILIC method. An in-depth analysis of the O-GalNAc glycosylation was performed, and 2093 intact glycopeptides were identified from 7.2 µL of human serum samples. This is the largest O-GalNAc glycosylation database of human serum from a trace amount of sample. Furthermore, 52 significantly changed intact O-GalNAc glycopeptides were determined by the quantitative analysis of hepatocellular carcinoma (HCC) and control serum samples, indicating the potential applications of this enrichment method in biomarker discovery.

Polyhedral oligomeric silsesquioxane grafted silica-based core-shell microspheres for reversed-phase high-performance liquid chromatography.

Polyhedral oligomeric silsesquioxane (POSS) was used to modify spherical silica to fabricate core-shell POSS@SiO2 microspheres. The material was characterized by Fourier transform infrared experiments, scanning electron microscopy, thermogravimetric analysis and elemental analysis. The material was also used as a stationary phase for HPLC separation. The POSS@SiO2 column exhibits a reverse-phase liquid chromatography (RPLC) retention mechanism. The column efficiency of alkylbenzenes reaches 67,200 plates·m-1. The POSS@SiO2 column was also utilized for separation of basic anilines and polycyclic aromatic hydrocarbons. Compared with the commercial C8 column, the POSS@SiO2 column exhibits enhanced separation selectivity. The column was also used for the separation of synthetic cytokinins 6-benzylaminopurine and 6-furfurylaminopurine in bean sprout after extraction. In addition, the methacrylate groups on the surface of the POSS@SiO2 microsphere were further functionalized so as to facilitate the fabrication of versatile stationary phases with various separation mechanisms. Graphical abstract Schematic presentation of the two-step fabrication of polyhedral oligomeric silsesquioxane grafted silica-based (POSS@SiO2) core-shell microspheres for use in HPLC.

Synthesis of Novel Pyrazole Derivatives as Promising DNA-Binding Agents and Evaluation of Antitumor and Antitopoisomerases I/II Activities.

Molecules bearing pyrazole nucleus present diverse biological properties such as antitumor and anti-inflammatory activities that can be associated with DNA interactions. This study aimed to the synthesis of new pyrazol derivatives and evaluated their ability to interact with the DNA and antitumor and topoisomerase inhibition activities. All derivatives were successfully synthesized, and their structures were elucidated by 1H-NMR and high resolution (HR)-MS (electrospray ionization positive mode (ESI+)). Antiproliferative inhibition assays, UV titration assays, fluorescence titration assays, circular dichroism (CD) assays, KI quenching studies, topoisomerase inhibitory activity assays and molecular docking were evaluated for these compounds. Especially, compounds 5e and 5q showed higher antitumor activity with IC50 values <13 µM for the tested cell lines. However, compounds 5e and 5q did not inhibit the topoisomerase activity evaluated by relaxation assay. These results show that the pyrazole nucleus contributes to the incorporation of molecules into the DNA. Moreover, it was highlighted that positive charges are relevant for the design of promising antitumor and DNA binding compounds.

Synthesis and biological evaluation of N-(carbobenzyloxy)-l-phenylalanine and N-(carbobenzyloxy)-l-aspartic acid-ß-benzyl ester derivatives as potent topoisomerase IIα inhibitors.

A new series of thirteen N-(carbobenzyloxy)-l-phenylalanine and N-(carbobenzyloxy)-l-aspartic acid-ß-benzyl ester compounds were synthesized and evaluated for antiproliferative activity against four different human cancer cell lines: cervical cancer (HeLa), lung cancer (A549), gastric cancer (MGC-803) and breast cancer (MCF-7) as well as topoisomerase I and IIα inhibitory activity. Compounds (5a, 5b, 5e, 8a, 8b) showed significant antiproliferative activity with low IC50 values against the four cancer cell lines. Equally, compounds 5a, 5b, 5e, 5f, 8a, 8d, 8e and 8f showed topoisomerase IIα inhibitory activity at 100µM with 5b, 5e, 8f exhibiting potential topoisomerase IIα inhibitory activity compared to positive control at 100µM and 20µM, respectively. Conversely compounds 5e, 5f, 5g and 8a showed weaker topoisomerase I inhibitory activity compared to positive control at 100µM. Compound 5b exhibited the most potent topoisomerase IIα inhibitory activity at low concentration and better antiproliferative activity against the four human cancer cell lines. The molecular interactions between compounds 5a-5g, 8a-8f and the topoisomerase IIα (PDB ID: 1ZXM) were further investigated through molecular docking. The results indicated that these compounds could serve as promising leads for further optimization as novel antitumor agents.

Periodic imidazolium-bridged hybrid monolith for high-efficiency capillary liquid chromatography with enhanced selectivity.

A novel periodic imidazolium-bridged hybrid monolithic column was developed. With diene imidazolium ionic liquid 1-allyl-3-vinylimidazolium bromide as both cross-linker and organic functionalized reagent, a new periodic imidazolium-bridged hybrid monolithic column was facilely prepared in capillary with homogeneously distributed cationic imidazolium by a one-step free-radical polymerization with polyhedral oligomeric silsesquioxane methacryl substituted. The successful preparation of the new column was verified by Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analysis, and surface area analysis. Most interestingly, the bonded amount of 1-allyl-3-vinylimidazolium bromide of the new column is three times higher than that of the conventional imidazolium-embedded hybrid monolithic column and the specific surface area of the column reached 478 m2 /g. The new column exhibited high stability, excellent separation efficiency, and enhanced separation selectivity. The column efficiency reached 151 000 plates/m for alkylbenzenes. Furthermore, the new column was successfully used for separation of highly polar nucleosides and nucleic acid bases with pure water as mobile phase and even bovine serum albumin tryptic digest. All these results demonstrate the periodic imidazolium-bridged hybrid monolithic column is a good separation media and can be used for chromatographic separation of small molecules and complex biological samples with high efficiency.

Design, Synthesis, Antifungal Activity and Molecular Docking of Thiochroman-4-one Derivatives.

N-Myristoyltransferase (NMT) has been validated pre-clinically as a target for treatment of fungal infections. Various substituted thiochroman-4-one derivatives have been synthesized by an efficient method. The synthesized compounds 7a-y and 8a-t were evaluated for their in vitro antifungal activity against the Canidia albicans, Cryptococcus neoformans, Epidermophyton floccosum, Mucor racemosus, Microsporum gypseum and Aspergillus nigerstrain. A series of compounds exhibited significant activity (minimal inhibitory concentrotion (MIC)=0.5-16 µg/mL) against Canidia albicans and Cryptococcus neoformans. The antifungal activity of compound 7b was reached to that of fluconazole, which can serve as a good starting point for further studies of structural diversity of the NMT inhibitors. The molecular docking studies revealed an interesting binding profile with very high receptor affinity for NMT of Canidia albicans.

[Synthesis and antifungal activities of N-1,3,4-thiadiazol-2-yl-4-oxo-thiochroman-2-yl-formamide derivatives].

Thiochromanones and 1,3,4-thiadiazoles as heterocyclic compounds have broad biological activities. In order to find novel compounds with antifungal bioactivity, substituted thiophenol and maleic anhydride were used to synthesize the intermediate 4-oxothiochromane-2-carboxylic acid. It was reacted with 2-amino-1,3,4-thiadiazole to get fourteen target compounds containing 1,3,4-thiadiazole moiety. The structures of the obtained compounds were confirmed by 1H NMR, 13C NMR and HR-MS. All compounds were investigated for antifungal activity via microdilution broth method. The results showed that the target compounds 3a and 3c to Epidermophyton floccosum and Mucor racemosus exhibited better antifungal activity than the positive control fluconazole, in which the minimum inhibition concentration can reach 8 µg·mL−1 and 16 µg·mL−1. Compound 3e showed significant inhibitory activity to Helminthosporium maydis, Sclerotinia sclerotiorum and Botrytis cinerea compared with that of the positive control carbendazim. Compound 3b exhibited inhibitory activity to Helminthosporium maydis better than the positive control carbendazim.

Imidazolium-embedded iodoacetamide-functionalized silica-based stationary phase for hydrophilic interaction/reversed-phase mixed-mode chromatography.

A novel imidazolium-embedded iodoacetamide-functionalized silica-based stationary phase has been prepared by surface radical chain-transfer polymerization. The stationary phase was characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, and element analysis. Fast and efficient separations of polar analytes, such as nucleosides and nucleic acid bases, water-soluble vitamins and saponins, were well achieved in hydrophilic interaction chromatography mode. Additionally, a mixed mode of hydrophilic interaction and reversed-phase could be also obtained in the analysis of polar and nonpolar compounds, including weak acidic phenols, basic anilines and positional isomers, with high resolution and molecular-planarity selectivity, outperforming the commercially available amino column. Moreover, simultaneous separation of polar and nonpolar compounds was also achieved. In conclusion, the multimodal retention capabilities of the imidazolium-embedded iodoacetamide-functionalized silica-based column could offer a wide range of retention behavior and flexible selectivity toward hydrophilic and hydrophobic compounds.

Novel pyridinium-based tags: synthesis and characterization for highly efficient analysis of thiol-containing peptides by mass spectrometry.

In this study, a novel type of pyridinium-based tags, 1-[3-[(2-iodo-1-oxoethyl)amino]propyl]-4-methylpyridinium bromide (IMP) and 1-[3-[(2-iodo-1-oxoethyl)amino]propyl]-4-propylpyridinium bromide (IPP), were designed, synthesized, and applied to the derivatization of thiol-containing peptides. With model peptides as the sample, the labeling efficiency and the stability of the peptide derivatives were investigated. The results indicate that nearly 100% derivatization yield was achieved with the developed tags and the peptide derivatives were stable at room temperature for at least one week. Furthermore, improved ionization efficiency and increased charge states were achieved via both matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MS) and electrospray ionization (ESI) MS, of which IPP exhibited the more obvious improvement of ionization efficiency. Further analysis of tryptic digests of bovine serum albumin (BSA) and α-transferrin, showed that increased identification efficiency of the thiol-containing peptides was achieved by combination with IMP or IPP derivatization. For example, the identification efficiency of the thiol-containing peptides of α-transferrin increased more than 42% upon combination with the IMP or IPP derivatives. We anticipate the novel tags are promising for highly efficient thiol-containing peptide identification in proteome research, especially for low concentrations.

Novel imidazolium-embedded N,N-dimethylaminopropyl-functionalized silica-based stationary phase for hydrophilic interaction/reversed-phase mixed-mode chromatography.

A novel imidazolium-embedded N,N-dimethylaminopropyl-functionalized silica-based stationary phase (Sil-ImCl) was prepared and further used for hydrophilic interaction/reversed-phase mixed-mode chromatography. The Sil-ImCl stationary phase was respectively characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, and element analysis. A variety of hydrophilic or hydrophobic compounds were used to evaluate the retention mechanisms of the developed stationary phase, and the effects of buffer salt concentration and pH of mobile phase on the retention of these compounds were also investigated. The developed stationary phase was successfully applied for separation of nucleosides and nucleic acid bases, water-soluble vitamins, phenols, and positional isomers. Moreover, simultaneous separation of polar and nonpolar compounds was also achieved with high resolution, outperforming the commercially available C8 column and amino column. Furthermore, the Sil-ImCl stationary phase has been successfully applied for separation of secondary metabolites of Hansfordia sinuosae. All these results demonstrate that the Sil-ImCl stationary phase might be promising for separation of complex polar and nonpolar compounds with high efficiency, especially in biological industry.

Development of a novel imidazolium-based aromatic quaternary ammonium tag: synthesis and application to the efficient analysis of cysteinyl-peptides by mass spectrometry.

RATIONALE: Chemical derivatization is a very promising technique for improving analysis of peptides by mass spectrometry (MS). In this study, a novel kind of imidazolium-based aromatic quaternary ammonium tag, 1-[3-[(2-iodo-1-oxoethyl)amino]propyl]-3-butylimidazolium bromide (IPBI), designed with strong gas-phase basicity and a permanent positive charge, was firstly synthesized and further used for derivatization of cysteinyl-peptides with improved ionization efficiency and higher charge states. METHODS: Both the model peptides and tryptic digests of proteins were used to evaluate the effect of IPBI derivatization on the MS performance of the derivatized peptides, and the results were further compared with the commonly used iodoacetamide (IAA) tag. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF)-MS and electrospray ionization (ESI)-MS were used to evaluate the ionization efficiency and charge states of the derivatized peptides. RESULTS: With model peptides as samples, a nearly 100% derivatization efficiency and superior stability were achieved via IPBI derivatization. By further analysis of both standard peptides and tryptic protein digests, the ionization efficiency and charge states of IPBI-derivatized peptides could be remarkably improved. For example, for protein bovine serum albumin, compared with the commercial available IAA tag, the identification efficiency of cysteinyl-peptides was increased about 67% by combining with IPBI derivatization. CONCLUSIONS: The results indicated that the novel tag is an effective derivatization reagent for cysteinyl-peptide identification. We hope it could be further used for high-efficiency cysteinyl-peptide identification in proteome research, especially those with low abundance and poor ionization efficiency.

Imidazolium-based iodoacetamide functional tags: design, synthesis, and property study for cysteinyl-peptide analysis by mass spectrometry.

New types of imidazolium-based iodoacetamide tags were designed, synthesized and further exploited for cysteinyl-peptide analysis with superior labeling efficiency, high stability, improved ionization efficiency, and increased charge states by mass spectrometry. For the first time, the effects of these kinds of tags on the mass spectrometry performance of the derivatized peptides were investigated, which is of great importance to help us design more efficient tags for the analysis of peptides or proteins, especially for those with low abundance.

[Transformation of scientific research results into teaching resources to improve the teaching effect: taking the teaching of the chromatographic method in the pharmaceutical analysis course as an example].

The pharmaceutical analysis course is a three-dimensional knowledge network that connects several courses to form a new comprehensive knowledge node involving a large knowledge system and flexible knowledge structure. In this course, the subject of chromatography covers a wide range of topics. However, because accurate content is challenging to present, the teaching effect of this subject is poor. In this work, we sought to achieve the educational purpose of establishing morality and cultivating talent, as well as the goal of training highly skilled professionals, by taking the teaching of chromatography in the pharmaceutical analysis course as an example of transforming scientific research results into teaching resources. The resources obtained are integrated into the teaching process to provide innovative and scientific research ideas to students with the aim of not only helping them understand and master technical knowledge but also exercise their ability to raise and solve problems. Furthermore, we expound on how to introduce scientific development frontiers and formulate scientific problems through curriculum design. We also describe how our strategy can promote the teaching effect and achieve teaching objectives. Based on the characteristics of rapid knowledge update and equal emphasis on theory and practice in pharmaceutical analysis, the course is designed by introducing new advances in scientific development, formulating scientific problems, and adopting question- and problem-based learning methods for teaching. The teaching effect is then evaluated through diversified assessment, student feedback, and self-evaluation. The results show that the transformation of scientific research results into teaching resources plays a significant role in stimulating students' interest in learning, improving students' ability to solve problems, and achieving curriculum objectives, all of which greatly improve the teaching effect.

A novel halloysite nanotubes-based hybrid monolith for in-tube solid-phase microextraction of polar cationic pesticides.

The accurate determination of polar cationic pesticides in food poses a challenge due to their high polarity and trace levels in complex matrices. This study hypothesized that the use of halloysite nanotubes (HNTs) can significantly enhance the extraction efficiency and sensitivity of these analytes because of their rich hydroxyl groups and cation exchange sites. Therefore, we chemically incorporated HNTs with organic polymer monoliths for in-tube solid-phase microextraction (SPME). This novel hybrid monolith extended service life, improved adsorption capacity, and exhibited excellent extraction performance for polar cationic pesticides. Based on these advancements, a robust and sensitive in-tube SPME-HILIC-MS/MS method was constructed to determine trace levels of polar cationic pesticides in complex food matrices. The method achieved limits of detection of 1.9, 2.1, and 0.1 µg/kg for maleic hydrazide, amitrole, and cyromazine, respectively. The spiked recoveries in five food samples ranged from 80.2 to 100.8%, with relative standard deviations below 10.7%.