Ligand-based magnetic extraction and safety assessment of zinc oxide nanoparticles in food products.

Zinc oxide (ZnO) is a zinc supplement widely used in health products and is approved by the FDA as Generally Regarded as Safe (GRAS). However, concerns have arisen regarding the potential health effects of nanoscale ZnO, as its reactivity differs from that of its bulk form. This has led to the need for an efficient method to extract ZnO from food products without altering its physicochemical properties, where conventional methods have proven to be inadequate. This study introduces an innovative approach using starch magnetic particles (SMPs) functionalized with a 12-amino acid peptide modified with five lysines (ZBP), that has specific affinity to ZnO. ZBP@SMPs effectively and rapidly extract intact ZnO from food products, achieving recovery efficiencies ranging from 60% to 90%, all while maintaining its morphology and crystallinity. The diameter of ZnO particles recovered from six commercial food products ranged from 25 to 500 nm, with 33% falling below 100 nm, highlighting the need for a size-dependent toxicity study. However, cytotoxicity assessment on human intestinal Caco-2 cells shows all ZnO samples affects cell proliferation and membrane integrity in a dose-dependent manner due to partial dissolution. This study contributes to understanding the safety of ZnO-containing food products and highlights potential health implications associated with their consumption.

Synthetic Ligand-Coated Starch Magnetic Microbeads for Selective Extraction of Food Additive Silicon Dioxide from Commercial Processed Food.

The amorphous form of silicon dioxide has long been regarded as a safe food additive (E551) that is widely used in commercially processed food as an anticaking agent. However, starting with titanium dioxide, there have been growing safety concerns regarding to the use of nanoscale silicon dioxide particles in food as food additives. The size, morphology, and chemical properties of inorganic food materials are important parameters to determine its potential toxicity. Therefore, an effective means of extracting an intact form of SiO2 from food without altering the physicochemical property of SiO2 particles is of great need to accurately monitor its characteristics. Here, we report on an effective magnetic separation method to extract food additive SiO2 from food by utilizing a diatom-originated peptide with a specific affinity to SiO2 particles. The affinity-based magnetic separation was found to be specific to SiO2 particles over other types of inorganic food additives such as titanium dioxide and zinc oxide. The size and morphology of SiO2 were shown to not be affected by the extraction processes. This method was successfully applied to extract and characterize the food additive SiO2 from six different types of commercial food.