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The concentrations of target analytes in samples are low, and complex matrices can lead to a variety of interferences. Therefore, it is important to pretreat the samples before analysis. Compared to the time-consuming, tedious, and environmentally unfriendly solvent-based sample pretreatment methods, pretreatment techniques based on adsorption have more promising applications. Adsorption-based pretreatment technologies include solid-phase extraction, dispersive solid-phase extraction, magnetic solid-phase extraction, and solid-phase microextraction. Among them, solid-phase microextraction integrates sampling, extraction, enrichment, and injection into a single step. It has the advantages of being solvent-free, highly efficient, time efficient, and labor efficient. The extraction efficiency of solid-phase microextraction is closely related to the coating materials. There are various types of coating materials, including metal-organic frameworks, covalent organic frameworks, molecular imprinted polymers, porous carbon materials and so on. Porous carbon materials include traditional porous carbon materials such as activated carbon, carbon nanotubes, carbon molecular sieves, and derived porous carbon materials. Given their advantages of large specific surface area, controllable porous structure, large number of active sites, as well as good physical and chemical stability, porous carbon materials have been widely used in batteries, supercapacitors, catalysis, adsorption, and separation. Porous carbon materials are also popular coating materials for solid-phase microextraction. In particular, derived porous carbon materials find widespread use given their variety and designability. Most of these materials are derived from biomass and metal-organic framework precursors. In addition, past studies have mainly focused on the structural optimization of derived porous carbon materials. However, the applications of derived porous carbon materials in solid-phase microextraction are restricted by the following problems. (1) The preparation of porous carbon materials derived from covalent organic frameworks has seen great progress. However, there are only a few studies on their applications in solid-phase microextraction. (2) The prepared-derived porous carbon materials have excellent extraction abilities as when applied to solid-phase microextraction coatings. However, there is less systematic and clear mechanism to explain it. (3) Most derived porous carbon materials when used as solid-phase microextraction coatings show nice extraction performance only for specific analytes such as polar or non-polar substances. Therefore, in this paper, the research progress of derived porous carbon materials in solid-phase microextraction over the past three years has been summarized, and future research prospects have been prospected. Covalent organic frameworks can be used as precursors to prepare derived porous carbon materials with a narrow pore size distribution and a large specific surface area. It is necessary to further develop porous carbon materials derived from covalent organic frameworks as solid-phase microextraction coatings. The specific mechanism underlying this extraction effect should also be clarified. In addition, it is necessary to develop high-performance derived porous coating materials for broad-spectrum and high-sensitivity analysis of pollutants with different physical and chemical properties. Therefore, hierarchical porous carbon materials should be widely studied in solid-phase microextraction because of their multimodal pore sizes. A total of 56 references are cited in this paper, most of which are from the Elsevier database.

Exercise training has been reported to alleviate cardiac fibrosis and ameliorate heart dysfunction after myocardial infarction (MI), but the molecular mechanism is still not fully clarified. Fibroblast growth factor 21 (FGF21) exerts a protective effect on the infarcted heart. This study investigates whether exercise training could increase FGF21 protein expression and regulate the transforming growth factor-β1 (TGF-β1)-Smad2/3-MMP2/9 signaling pathway to alleviate cardiac fibrosis following MI. Male wild type (WT) C57BL/6J mice and Fgf21 knockout (Fgf21 KO) mice were used to establish the MI model and subjected to five weeks of different types of exercise training. Both aerobic exercise training (AET) and resistance exercise training (RET) significantly alleviated cardiac dysfunction and fibrosis, up-regulated FGF21 protein expression, inhibited the activation of TGF-β1-Smad2/3-MMP2/9 signaling pathway and collagen production, and meanwhile, enhanced antioxidant capacity and reduced cell apoptosis in the infarcted heart. In contrast, knockout of Fgf21 weakened the cardioprotective effects of AET after MI. In vitro, cardiac fibroblasts (CFs) were isolated from neonatal mice hearts and treated with H2O2 (100 μM, 6 h). Recombinant human FGF21 (rhFGF21, 100 ng/mL, 15 h) and/or 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR, 1 mM, 15 h) inhibited H2O2-induced activation of the TGF-β1-Smad2/3-MMP2/9 signaling pathway, promoted CFs apoptosis and reduced collagen production. In conclusion, exercise training increases FGF21 protein expression, inactivates the TGF-β1-Smad2/3-MMP2/9 signaling pathway, alleviates cardiac fibrosis, oxidative stress, and cell apoptosis, and finally improves cardiac function in mice with MI. FGF21 plays an important role in the anti-fibrosis effect of exercise training.

Aromatic esters have been widely used in daily life with non-ignorable dangers, such as plasticizer, flavor, and preservative. Their wide applications and corresponding hazards caused by overuse have promoted the rapid development of sensitively analytical method for effective regulation. However, the variety makes it challenging for broad-spectrum and simultaneous extraction of diverse aromatic esters from the highly complex cosmetic samples. To our delight, a covalent organic framework, named DaTp (1, 3, 5-triformylphloroglucinol-2, 6-diaminoanthracene), possessing high specific surface, excellently thermochemical stability, and abundant electron-rich heteroatoms, has been synthesized and fabricated as a competitive solid phase microextraction coating for extracting the trace analytes with diverse polarity, through the hydrophobic interaction, π-π conjugation and hydrogen bond. Herein, this self-made SPME fiber has been further coupled with gas chromatography-tandem mass spectrometry (GC-MS) to determine the multi-polar aromatic esters in cosmetics packaged with plastic. This developed analytical method showed wide liner ranges, low limits of detection, good repeatability and reproducibility. Finally, the aromatic esters in four cosmetic samples were quantified precisely with satisfactory recoveries (80.7%-118%).