化学最新文献

The probiotic encapsulation system has the potential to enhance the prebiotic effects of probiotics. However, challenges arise from the release behavior of this system in vivo and the large size of hydrogel beads. This study aims to address the issues related to the size of previous hydrogel beads and assess the colon-targeted delivery of probiotic polysaccharides composite hydrogel beads (PPHB). PPHB prepared by gas-shearing technique significantly reduced the average particle size and demonstrated a high protective capacity for probiotics (after simulating intestinal conditions for 4 h, the viability of encapsulated probiotics remained at 10⁷ CFU/g). The use of indocyanine green along with near-infrared-II in vivo imaging technology demonstrated the colon-targeted delivery of PPHB in vivo, which also extended the retention time of probiotics in the cecum and colon. Additionally, the colon-targeted delivery of PPHB was also demonstrated by dietary supplementation in vivo. PPHB significantly enhanced the diversity and richness of intestinal microflora species, increased the levels of short-chain fatty acids, raised the relative abundance of beneficial bacteria, and significantly decreased the relative abundance of harmful bacteria. Alginate-based PPHB is more suitable for encapsulating functional ingredients for colon-targeted delivery and modulating gut microbiota.

The efficient isolation and lignin stabilization are critical to the fractionation process of lignocellulosic biomass, enabling the subsequent valorization of both carbohydrates and lignin. In this study, a ternary deep eutectic solvent pretreatment system with outstanding reusability has been developed. Under optimal conditions (ChCl: MT: p-TsOH = 1:1:0.5, 120 °C, 60 min), the system efficiently removed 94.66 % of hemicellulose and 95.74 % of lignin while retaining 84.50 % of cellulose. Glucose was obtained from the cellulose-rich solid residue via enzymatic hydrolysis, achieving an 87.12 % yield. This DES system inhibits lignin condensation through a dual mechanism of α-etherification and intermolecular forces (π-π stacking and hydrophobic interaction). The recovered lignin exhibits a low molecular weight (922-1049 g/mol), high phenolic hydroxyl content (2.57-3.37 mmol/g), low polydispersity (1.54-1.61), and high purity (93.02 %). Combined with its superior antioxidant activity and UV shielding properties, this lignin represents a promising new resource with potential applications.

Tyrosinase is a rate-limiting enzyme for melanogenesis and abnormal melanin production can be controlled by utilizing tyrosinase inhibitory substances. To develop potent and safe inhibitors of tyrosinase, complex tannins a narrowly distributed plant polyphenols were prepared from the fruit peel of Euryale ferox (EPTs) and then structurally characterized, as well as investigated for their inhibitory effects and the involved mechanisms against tyrosinase activity and melanogenesis. The structures of EPTs were established to consist of 63.49% hydrolyzable tannins and 36.51% flavan-3-ol units. EPTs inhibited both the monophenolase and diphenolase activities of tyrosinase efficiently. This outstanding inhibition was presumably ascribed to the strong copper-ion chelating ability of EPTs and the microenvironment modification and secondary structure rearrangement of tyrosinase caused by the formation of EPTs-tyrosinase complexes. Treatment of EPTs to B16F10 cells also decreased the intracellular tyrosinase activity, induced apoptosis and G2/M cell cycle arrest, suppressed melanoma cell proliferation and downregulated the mRNA expression of tyrosinase, TRP-1 and MITF, consequently leading to a distinct reduction in melanin content. Furthermore, EPTs exhibited powerful antioxidant properties, which maybe contributed to impeding the initial steps of melanin formation. This study offered theoretical guidance for the potential applications of EPTs in cosmetic, functional food and medical industries.

Polylactide (PLA) occupies the first position in the global production market of bioplastics, generating a large amount of waste. Cutinases have high potential to depolymerize plastic polyesters like PLA, since cutin, their natural substrate, is structurally similar. Here, the cutinase secreted by Fusarium solani (FsC) was heterologously produced in high yields, and its hydrolytic efficiency on PLA polymers of different stereochemistry, crystallinity, and polymerization degree was evaluated. Under the conditions tested, FsC proved to be enantioselective, with poly(D,L-lactic acid) (PDLLA) as its best substrate and no activity on poly(L-lactic acid) (PLLA). The hydrolysis of PDLLA was optimized by Response Surface Methodology (p-value <0.0001). After optimization, over 8 g/L of lactic acid were recovered from 10 g/L PDLLA in 15 h at 50 °C. This outstanding performance highlights the potential of FsC for its further improvement through computational design, with a focus on broadening its activity range or substrate versatility.

Terpenoids are widely distributed in plants and are often used as defense molecules in plant-microbe interactions. However, endophytic microorganisms usually establish a better symbiotic relationship with their hosts by secreting enzymes to avoid defense plant metabolites. This study evaluated the in vitro biotransformation activity of licorice endophytic fungi on glycyrrhizin and further explored the molecular regulation of their in vivo colonization on the licorice growth and metabolism. The results indicated that licorice endophytic fungi generally possessed the ability to bio-transform glycyrrhizin, with Z6 and Z15 exhibiting glycyrrhizin-induced β-glucuronidase activity. The Z6GH2 and Z15GH2 proteins were identified to hydrolyze glycyrrhizin in different ways by prokaryotic and eukaryotic experiments. In vivo re-infestation of licorice by Z6 and Z15 revealed significant promotion of glycyrrhizin biosynthesis and accumulation by regulating the expression levels of genes involved in glycolysis and glycyrrhizin biosynthesis pathway in licorice. These findings were further validated in J3, which has glycyrrhizin biotransformation properties. In summary, this study reveals the molecular mechanism by which endophytic fungi with glycyrrhizin β-glucuronidase activity promote glycyrrhizin biosynthesis and accumulation in licorice through feedback regulation of its metabolic flux. These finding highlight the importance of endophytic fungi in regulating the accumulation of active ingredients in medicinal plants.

Slowly digestible starches, known to confer health benefits, are often prepared via compounding with other substances. However, starch complexes often encounter problems such as low viscosity. This work aimed to develop a corn starch/type-A gelatin (CS/GA) complex that simultaneously exhibited rapidly digestible starch (RDS) reduction, and superior viscosity. The pH and drying temperature of the complexes were systematically optimized, and a novel freeze-thaw pretreatment (FTP) technique was innovatively introduced. This work investigated the effects of varying FTP cycles (ranging from 0 to 8) on the physicochemical properties of CS/GA complexes. Results showed that FTP significantly enhanced the viscosity of the complexes while effective RDS reduction. Notably, after six FTP cycles, the complexes attained optimal properties, characterized by the highest the complex index (CI), relative crystallinity (RC) and short-range molecular order, accompanied by the lowest RDS reduction of 46.24 %. The multivariate analysis revealed CI as the crucial parameter for altering the resistant starch (RS) content. Furthermore, FTP induced cracking on the surface of starch particles was observed. In conclusion, these results were of significance for developing CS-based food materials with RDS reduction, and high viscosity characteristics, such as noodles, corn porridge and sausage.

This study presents the development of intelligent screen-printed labels for real-time food freshness monitoring. Using chitosan grafted with rosolic acid (RA) and immobilized on montmorillonite (MMT) through cationic exchange, a hybrid dye was synthesized and applied in screen-printing inks. The hybrid structure was characterized by XRD, TGA, and UV-vis, confirming improved thermal stability and maintained halochromic properties. SEM analysis showed consistent ink deposition on filter paper, while water contact angle (WCA) measurements demonstrated enhanced surface hydrophobicity due to the MMT. The labels exhibited clear pH-sensitive color transitions from yellow to purplish red (pH 2.0-12.0) and rapid ammonia sensitivity, with ΔE values exceeding 45.0 within 10 min. The labels also demonstrated excellent reversibility, storage stability, leaching resistance, and cytocompatibility. Practical tests on shrimp and milk confirmed the labels' ability to accurately monitor freshness through visible color changes. These findings highlight the potential of hybrid labels as effective, scalable freshness indicators for intelligent food packaging.

The individualized administration and pharmacokinetics profiling are integral to the safe use of antibody drugs in immunotherapy. Here, we propose an electrochemical platform for the highly sensitive and selective detection of antibody drugs, taking advantage of the affinity capture by the peptide mimotopes together with the signal amplification by the biologically-driven RAFT polymerization (BDRP). Briefly, the BDRP-based platform involves the capture of antibody drugs by peptide mimotopes, the labeling of multiple reversible addition-fragmentation chain-transfer (RAFT) agents to the glycan chains of antibody drugs, and the BDRP-enabled controlled recruitment of numerous redox labels. The BDRP-based signal amplification relies on the reduction of RAFT agents by NADH coenzymes into the carbon-centered radicals, which can propagate efficiently into long polymer chains by reacting with the ferrocene-derivated monomers, recruiting numerous redox labels to the glycan chains of antibody drugs. The BDRP is conducted at the physiological temperature (i.e., 37 °C) and in the absence of external stimuli or radical sources, holding the advantages of biological compatibility and desirable simplicity over conventional RAFT polymerization approaches. The developed platform is highly selective and the detection limit in the presence of rituximab as the target was determined to be 0.14 ng/mL. Moreover, the applicability of the BDRP-based platform in the sensitive assay of antibody drugs in serum samples has been validated. In view of the biocompatibility, desirable simplicity, and cost-effectiveness, the BDRP-based platform shows great promise in the quantitative assay of antibody drugs.

A manganese porphyrin wrapped DNA dendrimer (Mn-DD) was developed through enzyme-free DNA self-assembly and simple and mild groove binding of porphyrin. The Mn-DD not only possessed plenty of manganese porphyrin to amplify the chemiluminescence (CL) signal, but also can be modified with diverse groups via DNA hybridization. Combined with an immunosensor array, Mn-DD can be utilized for CL immunoassay of multiple mycotoxins as a universal tag. Under optimal conditions, Mn-DD-based CL imaging immunoassay of aflatoxin B₁ (AFB₁), ochratoxin A (OTA), and zearalenone (ZEN) exhibited broad linear ranges over 4 orders of magnitude and detection limits as low as 0.87, 0.75, and 0.79 pg mL^-1, respectively. It was also utilized in the examination of real coix seed samples, yielding reliable results. High sensitivity, as well as simple operation, low reagent dosage, acceptable accuracy and stability showed the tag and the approach broad application prospects in quality control of food and medicine.

The rapid advancement of the Internet of Things has created a substantial demand for portable gas sensors. Nevertheless, the development of gas sensors that can fulfill the demanding criteria of high sensitivity and rapid response time continues to pose a considerable challenge. Herein, an in-situ anchoring strategy is proposed to construct CNTs@MOF heterostructure to establish strong electronic coupling and charge relocation for enhancing the monitoring capabilities of isopropanol (freshness markers for fruits) at room temperature. The in-situ anchoring process prevents Zn-MOF (ZIF-8) self-aggregation, ensuring efficient transport channels for target analytes and enhancing active site utilization. Moreover, the synergistic effect of each component in the composite is optimized. Consequently, the gas sensor based on the CNTs@ZIF-8 heterostructure achieved an ultrahigh isopropanol response of 57.87 (40 ppm, R_a/R_g) at room temperature and 60% relative humidity, exhibiting rapid response kinetics (38 s, 30 ppm) and durability. This study offers a fresh perspective on the structural design of oxygen-inert CNTs materials.