Green synthesis of Zn2+ nanocarriers from Auricularia auricula fermentation broth with excellent antioxidant activity.

Nanoparticles (NPs) possessing nanoscale dimensions and remarkable antioxidant activity were synthesized via a green hydrothermal method utilizing Auricularia auricula fermentation broth, referred to as AFNPs. The functional groups on the surface of the AFNPs significantly contributed to the formation of AFNPs-Zn2+. The AFNPs-Zn2+ appeared a zinc retention rate of 40.80 % after gastrointestinal digestion. When compared to typical zinc supplements, AFNPs-Zn2+ did not exhibit visible cytotoxicity or hemolysis. Furthermore, AFNPs-Zn2+ demonstrated the ability to mitigate cell damage resulting from zinc deficiency. In vivo experiments showed that AFNPs-Zn2+ were mainly observed in the stomach, intestine, kidney, and testis after oral administration. In vivo distribution experiments indicated predominant presence of AFNPs-Zn2+ in the stomach, intestine, kidney, and testis following oral administration. This study highlights the potential for Auricularia auricula NPs to serve as the efficient, stable, and safe nanocarriers for Zn2+.

Change of Cell Toxicity of Food-Borne Nanoparticles after Forming Protein Coronas with Human Serum Albumin.

Nanoparticles (NPs) can form protein coronas with plasma proteins after entering the biological environment due to their surface adsorption ability. In this study, the effects of protein coronas of roast squid food-borne nanoparticles (FNPs) with human serum albumin (HSA) on the HepG-2 and normal rat kidney (NRK) cells were investigated. The hydrodynamic diameters of the HSA and HSA-FNPs were 8 and 13 nm, respectively. The cytotoxicity and cell membrane damage of FNPs to HepG-2 cells increased with the increase of roasting temperature. The presence of 4.78 × 10-3 mol/L FNPs increased the numbers of cellular necrosis and prolonged the G2 phase of the cell cycle. The formation of protein coronas of squid FNPs mitigated the autophagy phenomenon by FNPs on HepG-2 cells. Moreover, protein coronas reduced the mitochondrial membrane potential in the HepG-2 and NRK cells and the production of reactive oxygen species caused by FNPs. The abnormal contents of oxidative stress indicators such as glutathione, superoxide dismutase, malondialdehyde, and catalase in HepG-2 and NRK cells induced by FNPs were alleviated due to the presence of HSA. These results suggested that the protein coronas formed by HSA on FNPs mitigated the cytotoxicity compared with the bare FNPs, thus providing insights into the interaction of squid FNPs with HSA.

Food-Borne Nanocarriers for Calcium Delivery: A New Choice for Nutrient Supplements.

Calcium is considered as an important nutrient element for the maintenance of human health, and food-borne nanoparticles (FNs) produced during food processing may have potential as nanocarriers for calcium ion delivery. Beef is an important source of animal protein that has high protein and low fat content and is rich in a variety of amino acids; thus, beef may be a suitable material for the development of calcium nanocarriers. In this paper, FNs were synthesized from beef by one-step hydrothermal synthesis. The FNs had a spherical shape with a size of about 3.0 nm and emitted a bright blue fluorescence under 365 nm ultraviolet irradiation. The amino nitrogen atom and carboxyl oxygen atom of the functional groups on the surface of the FNs were the main binding sites for the chelation of Ca(II). The size of the FNs-Ca(II) complex was about 4.75 nm, and the specific signal peak of calcium at 3.7 keV was observed in its energy dispersive X-ray spectroscopy spectrum. The viability of cells treated with FNs-Ca(II) was more than 65%, while viability was only 60% after treatment with CaCl2. The results showed that the FNs from beef have great potential in calcium delivery for the development of a calcium supplement.

Endogenous Fluorescence Carbon Dots Derived from Food Items.

BACKGROUND: Fluorescent carbon dots (CDs) are a novel class of carbon-based nanomaterials that were discovered in 2004. However, nobody knew that CDs existed in food items naturally until 2012. Properties of nanosize materials are distinct from those of their bulk materials due to the particle size and accordingly alter their bioavailability and/or biocompatibility. Therefore, the potential health risk of nanoparticles in food has drawn massive attention. Currently, almost all studies regarding the biosafety of nanoparticles in food have mainly focused on engineered nanoparticles used as food additives and have excluded the endogenous nanoparticles in food. Therefore, investigation of the properties of food-borne fluorescent CDs and their potential health risk to humans is of great significance. SCOPE AND APPROACH: This review summarizes the existing literature on fluorescent carbon dots (CDs) in food, with particular attention to their properties, formation process, and the potential health risks posed to consumers. The knowledge gap between food-borne nanoparticles and their potential risks is identified, and future research is proposed. KEY FINDINGS AND CONCLUSIONS: The presence of fluorescent CDs in food produced during food processing has been summarized. Fluorescent CDs less than 10 nm in size mainly contain carbon, oxygen, hydrogen, and/or nitrogen. The presence of CDs in food items was first demonstrated in 2012, and their formation was attributed to heating of the starting material. The properties of CDs in food are different from the engineered nanoparticles used as food as additives and represent a novel kind of nanostructure in food. Further studies should focus on the chronic effects of CDs, although their toxicity is low, because investigations both in vivo and in vitro are limited.