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Herein, the zwitterionic material poly (carboxybetaine acrylamide) was grafted onto iron oxide to obtain biocompatible magnetic nanoparticles Fe 3 O 4 -pCBAA which were employed to immobilize enzymes. The nanocomplxes Fe 3 O 4 -pCBAA were characterized using scanning electron microscopy (SEM), dynamic light scattering (DLS), zeta potential, Fourier transform-infrared (FT-IR) spectra and energy dispersive X-ray spectrometry (EDX). The urease as a model enzyme was immobilized with the novel supports and the properties of immobilized urease were further investigated in comparison with the free urease counterpart. The immobilized urease exhibited excellent thermodynamic and chemical stability. Particularly, 60% of initial activity was remained after being stored at 70 °C for 2 h while the free urease only remained 30%. Besides, the relative activity of immobilized enzyme was 1.7 times that of free ones after disposed in ethanol and 2-propanol for 2 h, and 7 times in DMF. Moreover, immobilized urease retained >80% of its initial activity after 5 cycles. In addition, the immobilization carrier Fe 3 O 4 -pCBAA displayed famous biocompatibility, and the immobilized urease performed better in complex biological samples, which were >85% and <60% of its initial activity for the immobilized and dissociative urease, respectively, in 20% and 25% of serum. These results confirm that the nanoparticles Fe 3 O 4 -pCBAA are biofriendly and efficient supports for enzyme immobilization and potential for practical applications in bio-microenvironments. [ABSTRACT FROM AUTHOR]

Curcumin (Cur) exhibits low water solubility and insufficient dispersibility in food systems, and cannot exert its excellent antioxidant properties. In this work, Chitosan (CS) nanoparticles were prepared by ionic crosslinking method using chitosan as carrier and sodium tripolyphosphate (TPP) as crosslinking agent, then Cur was loaded to obtain curcumin nanoparticles (CNPs). CNPs presented a spherical morphology with average size of 278.9 nm. Compared with the solubility of native Cur (0.017 μg/mL) at 25 °C, the water solubility of CNPs increased to 35.92 μg/mL of more than 2100 times. In addition, the antioxidant capacity of Cur was also studied based on DPPH free radical scavenging, the results showed that with the increase of the concentration, the antioxidant capacity of CNPs was significantly increased (p < 0.05), which was higher than that of Cur at the same concentration. The edible coating was prepared by adding CNPs into sodium carboxymethyl cellulose (CMC) to study the effects of CMC-CNPs coatings in improving the quality and shelf life of fresh pork stored at 4 ± 1 °C for 15 days. The results showed that CMC-CNPs edible coating could significantly inhibit lipid oxidation of fresh pork (p < 0.05) and could be further applied in lipid rich food packaging. [ABSTRACT FROM AUTHOR]

The occurrence of Maillard reaction in protein – polysaccharide coacervated microcapsules and its effects on microcapsule properties were investigated. Vitamin E microcapsules were prepared by soybean protein isolate – chitosan coacervation at 50 °C, 70 °C, or 90 °C for 12 h in the presence of maltose. Chromatic and furosine measurements revealed that Maillard reaction occurred in the microcapsules and was favored by high incubation temperatures. The three coacervation temperatures did not destroy the microcapsule structure, but improved the microencapsulation efficiency and microencapsulation yield instead. The microcapsules exhibited decreased aggregation and the increased absolute zeta potential and particle size were believed contribute to this improvement. Stability analysis demonstrated that the microcapsules possessed enhanced resistance to dissolution in water and improved storage stability than control microcapsules. It is concluded that coacervation at a temperature high enough to initiate Maillard reaction is a promising way to improve the physiochemical properties of protein – polysaccharide coacervated microcapsules. • Heating at 50 °C and higher initiated Maillard reaction in coacervated capsules. • Maillard reaction reduced microcapsule aggregation and increased particle size. • Maillard reaction led to improved microencapsulation performance. • Maillard reaction conferred enhanced stability against dissolution in water. • Maillard reaction conferred enhanced storage stability. [ABSTRACT FROM AUTHOR]

S. cerevisiae -derived-beta- d -glucan (S. cerevisiae -BG) is a natural polysaccharide with various biological effects. The present study was to investigate the protective effect of S. cerevisiae -BG on the injury induced by high linear-energy-transfer (LET) carbon ion irradiation and to reveal the protective mechanisms. Female mice were orally administrated with S. cerevisiae -BG before irradiation. 30-day survival of 6 Gy irradiated-mice was monitored. The damage and recovery of hematopoietic system were evaluated after 2 Gy irradiation, cytokines in plasma were detected, transcriptomics of bone marrow mononuclear cells (BMMNCs) were detected and analyzed. The mortality results showed that S. cerevisiae -BG could prolong the survival of mice exposed to 6 Gy. The results of BMMNCs injury analysis showed that S. cerevisiae -BG could reduce the ROS level, mitigate DNA damage and apoptosis. S. cerevisiae -BG increased the plasma radioprotective cytokines level in irradiated mice. Transcriptomics analysis revealed that S. cerevisiae -BG modulated the gene expression in BMMNCs of irradiated mice, 256 genes were significantly up-regulated and 97 genes were significantly down-regulated. Gene function and Gene Ontology analysis indicated the key genes related to hematopoiesis and immunity. Pathway analysis revealed that these up-regulated genes mainly focus on PI3K-Akt pathway and down-regulated genes mainly focus on MAPK pathway. These data contribute to understanding the molecular mechanisms of the radioprotective effect of S. cerevisiae -BG. • S. cerevisiae -BG prolonged the survival of carbon ion irradiated mice. • S. cerevisiae -BG ameliorates carbon ion irradiation-induced murine myelosuppression. • S. cerevisiae -BG affected transcriptomic response of radiotoxicity in bone marrow. • S. cerevisiae -BG mainly regulated PI3K-Akt and MAPK pathway for radioprotection. [ABSTRACT FROM AUTHOR]

Clay mineral-based hemostatic materials have attracted much attention in recent years, but it is scarce to report the hemostatic nanocomposite films containing natural mixed-dimensional clay composed of natural one-dimensional and two-dimensional clay minerals. In this study, the high-performance hemostatic nanocomposite films were facilely prepared by incorporating the natural mixed-dimensional palygorskite clay leached by oxalic acid (O-MDPal) into chitosan/polyvinylpyrrolidone (CS/PVP) matrix. By contrast, the obtained nanocomposite films exhibited the higher tensile strength (27.92 MPa), lower water contact angel (75.40°), better degradation, thermal stability and biocompatibility after incorporation of 20 wt% of O-MDPal, suggesting that O-MDPal contributed to enhancing the mechanical performance and water holding capacity of the CS/PVP nanocomposite films. Compared with the medical gauze and CS/PVP matrix groups, the nanocomposite films also indicated excellent hemostatic performance evaluated by blood loss and hemostasis time indexes based on the mouse tail amputation model, which might be ascribed to the enriched hemostatic functional sites, and hydrophilic surface, robust physical barrier role of nanocomposite films. Therefore, the nanocomposite film exhibited a promising practical application in wound healing. • Natural MDPal was employed to prepare CS/PVP nanocomposite films with excellent hemostatic activity. • Nancomposite films containing 20 wt% of MDPal exhibited the highest tensile strength of 27.92 MPa. • High hemostatic mechanisms involved in absorbing liquid, stimulating platelet activation and aggregating. • Nanocomposite films exhibited preeminent biocompatibility. [ABSTRACT FROM AUTHOR]