Interaction between bovine serum albumin and chitooligosaccharides: I. Molecular mechanism

Enhanced stability of Pickering emulsions through co-stabilization with nanoliposomes and thermally denatured ovalbumin

Pickering emulsions were co-stabilized by nanoliposome (NL) and thermally denatured ovalbumin (DOVA) based on the induction of OVA with strong particle characteristics through thermal denaturation. DOVA-NL particles were spherical and their sizes were mainly distributed between 50 and 100 nm. The surface tension and interfacial tension of DOVA-NL were significantly reduced, and the surface hydrophobicity, amphiphilicity and free -SH content of DOVA were enhanced after complexation with NL. The content of α-helix and β-sheet in DOVA decreased, whereas the content of β-turn and random coil increased after complexation with NL. Hydrophobic interactions, hydrogen bonding and electrostatic forces played a vital role in the interactions between NL and DOVA, leading to conformational changes in DOVA. The number of binding sites between NL and DOVA was more than one, and the interaction between NL and DOVA was exothermic and spontaneous. The emulsification index showed that DOVA-NL-stabilized Pickering emulsions (DNPE) were significantly more stable than DOVA-stabilized emulsions. DOVA-NL particles adsorbed at the oil-water interface and the droplet size of DNPE was smaller than that of DOVA-stabilized emulsions. This study suggests that it may be an effective strategy to improve the stability of Pickering emulsions through co-stabilization with NL and DOVA.

Synergistic Antimicrobial Hybrid Bio-Surface Formed by Self-Assembled BSA Nanoarchitectures with Chitosan Oligosaccharide

Innovation in green, convenient, and sustainable antimicrobial packaging materials for food is an inevitable trend to address global food waste challenges caused by microbial contamination. In this study, we developed a biogenic, hydrophobic, and antimicrobial protein network coating for food packaging. Experimental results show that disulfide bond breakage can induce the self-assembly of bovine albumin (BSA) into protein networks driven by hydrophobic interactions, and chitosan oligosaccharide (COS) with antimicrobial activity can be stably bound in this network by electrostatic interactions. The inherent antimicrobial activity of COS and the numerous hydrophobic regions on the surface of the BSA-network give the BSA@COS-network significant in vitro antimicrobial ability. More importantly, the BSA@COS-network coating can prolong the onset of spoilage of strawberries in various packaging materials by nearly 3-fold in storage. This study shows how surface functionalization via protein self-assembly is integrated with the biological functioning of natural antibacterial activity for advanced food packaging applications.

Interaction between Chinese quince fruit proanthocyanidins and bovine serum albumin: Antioxidant activity, thermal stability and heterocyclic amine inhibition

Heterocyclic amines (HCAs) are carcinogenic and mutagenic substances produced in fried meat. Adding natural antioxidants (e.g., proanthocyanidins (PAs)) is a common method to reduce HCAs; however, the interaction between the PAs and protein can affect the inhibitory efficacy of PAs on the formation of HCAs. In this study, two PAs (F1 and F2) with different degrees of polymerization (DP) were extracted from Chinese quince fruits. These were combined with bovine serum albumin (BSA). The thermal stability, antioxidant capacity and HCAs inhibition of all four (F1, F2, F1-BSA, F2-BSA) were compared. The results showed that F1 and F2 interact with BSA to form complexes. Circular dichroism spectra indicate that complexes had fewer α-helices and more β-sheets, β-turns and random coils than BSA. Molecular docking studies indicated that hydrogen bonds and hydrophobic interactions are the forces holding the complexes together. The thermal stabilities of F1 and, particularly, F2 were stronger than those of F1-BSA and F2-BSA. Interestingly, F1-BSA and F2-BSA showed increased antioxidant activity with increasing temperature. F1-BSA's and F2-BSA's HCAs inhibition was stronger than F1 and F2, reaching 72.06 % and 76.3 %, respectively, for norharman. This suggests that PAs can be used as natural antioxidants for reducing the HCAs in fried foods.

Chitosan oligosaccharide alleviates and removes the toxicological effects of organophosphorus pesticide chlorpyrifos residues

The abuse of chlorpyrifos (CHP), a commonly used organophosphorus pesticide, has caused many environmental pollution problems, especially its toxicological effects on non-target organisms. First, CHP enriched on the surface of plants enters ecosystem circulation along the food chain. Second, direct inflow of CHP into the water environment under the action of rainwater runoff inevitably causes toxicity to non-target organisms. Therefore, we used rats as a model to establish a CHP exposure toxicity model and studied the effects of CHP in rats. In addition, to alleviate and remove the injuries caused by residual chlorpyrifos in vivo, we explored the alleviation effect of chitosan oligosaccharide (COS) on CHP toxicity in rats by exploiting its high water solubility and natural biological activity. The results showed that CHP can induce the toxicological effects of intestinal antioxidant changes, inflammation, apoptosis, intestinal barrier damage, and metabolic dysfunction in rats, and COS has excellent removal and mitigation effects on the toxic damage caused by residual CHP in the environment. In summary, COS showed significant biological effects in removing and mitigating blood biochemistry, antioxidants, inflammation, apoptosis, gut barrier structure, and metabolic function changes induced by residual CHP in the environment.

The influence of surface charge on the tumor-targeting behavior of Fe3O4 nanoparticles for MRI

Nanomedicine-based tumor-targeted therapy has emerged as a promising strategy to overcome the lack of specificity of conventional chemotherapeutic agents. "Passive" targeting caused by the tumor EPR effect and "active" targeting endowed by the tumor-targeting moieties provide promising biomedical utilities and cancer therapy strategies for nanomedicine. However, as the nanoparticles are exposed to biological fluids, a large number of protein molecules will be adsorbed on their surface, known as protein corona, which may alter the targeting ability of the nanoparticles. The impact of different protein corona on the "passive" and "active" targeting behaviors is still ambiguous. Herein, three kinds of aqueous soluble Fe₃O₄ nanoparticles with different surface modifications were synthesized and applied to explore the correlation between their protein corona and passive/active tumor-targeting abilities. In the in vitro and in vivo studies, the protein corona exhibited completely different effects on the active and passive cancer-targeting capability of the particles. The particles presented active cancer-targeting ability if there was enough interaction time between the particles and cells. This was mainly due to the dynamic evolution of the protein corona, the proteins of which may be outcompeted by the cancer cell membrane and determine the targeting abilities. Unfortunately, the protein corona also inevitably accelerated RES/MPS uptake after the particles were injected into the body, which almost completely disabled the active targeting abilities of the particles. We believe that this in-depth understanding of protein corona will provide new ideas on the tumor-targeting mechanisms of nanoparticles and present a feasible approach to designing targeted drugs in the future.