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.

Facile preparation of highly uniform type 3 resistant starch nanoparticles.

Resistant starch (RS) has emerged as a promising functional food ingredient. To improve the textural and sensory characteristics of RS, there need to be an effective approach to produce RS with well-defined size and shape. Here, we present a facile approach for the synthesis of highly uniform resistant starch nanoparticles (RSNP) based on recrystallization of short-chain glucan (SCG) originated from debranched starch. We found that the ratio of SCG to partially debranched amylopectin was a key parameter in regulating the morphology, size, and crystallinity of the nanoparticles, which enable us to prepare highly uniform RSNP with an average diameter of around 150 nm, while showing a good colloidal stability over a broad range of pH (2-10). Moreover, the in-vitro digestibility and RS content of RSNP was not affected over the ten successive cycles of assembly and disassembly, which would provide useful insights for the development of RS-based functional food ingredients.

Modulation of the peroxidase-like activity of iron oxide nanoparticles by surface functionalization with polysaccharides and its application for the detection of glutathione.

Here, we employed three polysaccharides, such as dextran, hyaluronic acid, and chitosan, for surface modification of iron oxide nanoparticles (IONPs) and carried out in-depth investigation to elucidate the effect of surface functionalities on the peroxidase (POD) like activity of IONPs. The affinity of substrates to the catalytic site of IONPs was found to be determined by the surface functional groups and hydration layer of polysaccharide coating on the surface of IONPs. The role of hydration layer was further confirmed by the results that the POD-like activity of IONPs coated with a certain polysaccharide having higher water holding capacity was significantly enhanced by salting-out reagent, such as ammonium chloride that is known to reduce the thickness of hydration layer. Moreover, the excellent catalytic activity of dextran-coated IONPs was successfully applied to develop a highly sensitive sensing system for the detection of glutathione (GSH) with a limit of detection of 2.3 nM.

Preparation of starch-based drug delivery system through the self-assembly of short chain glucans and control of its release property.

Here, we report a starch-based carrier system for the delivery of insoluble bioactive compound via oral route. We utilized the intrinsic characteristics of debranched amylopectins that self-assemble into a spherical microparticle in aqueous environment to encapsulate guest molecules. Upon complexation with ß-cyclodextrin, the model bioactive compound, curcumin (CUR), was effectively incorporated into the starch microparticles (SMPs) to form CUR-CD@SMPs during the self-assembly reaction. The stability of encapsulated curcumin against environmental stresses, such as photodegradation and chemical oxidation, was greatly enhanced upon encapsulation. The size of CUR-CD@SMPs could be precisely controlled from 0.3 µm to 2 µm by modulating the rate of debranching reaction. A change of release profiles from concave-downward to sigmoidal form was observed upon increasing the size of CUR-CD@SMPs, suggesting that the release site could be controlled by modulating the crystallinity or size of the carrier microparticles.

Charge-switchable magnetic separation and characterization of food additive titanium dioxide nanoparticles from commercial food.

Growing concerns about the potential health effects of nanoscale titanium dioxide (TiO2) have necessitated the need for monitoring the size distribution and physicochemical properties of food additive TiO2 that are present in commercial food. Acid digestion is by far the most widely used method to remove interfering food matrices, but the highly corrosive nature of the reaction could alter the physicochemical properties of the TiO2, which may give a skewed information about the materials. Here, we report an effective approach to extract intact form of food additive TiO2 nanoparticles from processed food through charge-charge interaction between TiO2 particles and charge-switchable starch magnetic beads (PL@SMBs), of which the captured TiO2 is readily harvested by switching the surface charge of PL@SMBs to neutral. The size and surface property of extracted TiO2 were shown to be well maintained due to the mild nature of the reaction. The extracted TiO2 particles from 10 commercial processed food showed a size distribution from 40 to 250 nm with a mean diameter of 115 nm, of which 22 % of them were less than 100 nm. The extracted TiO2 did not exhibit short-term cytotoxicity, but induced cellular oxidative stress at high concentration.

Synthesis of monodisperse starch microparticles through molecular rearrangement of short-chain glucans from natural waxy maize starch.

Here, we report a sustainable approach for the synthesis of starch-based microparticles with well-defined shape and size through molecular self-assembly of short-chain glucan (SCG) obtained enzymatically from waxy maize starch. We employed chitosan as a steric stabilizer to modulate the nucleation process, which significantly reduced undesirable aggregations during the nucleation and growth phases, resulting in the production of highly monodisperse microparticles. The size of chitosan-assisted starch microparticles (CS-SMPs) was effectively controlled by the concentration of debranching enzyme as well as by debranching time, of which the factors influencing the final size were investigated. By modulating the rate and time of debranching reaction in combination with the steric stabilizing effect of chitosan, we were able to prepare highly monodisperse CS-SMPs from 200 nm to 5 µm with a production yield of over 70% from natural starch. Furthermore, the potential of CS-SMPs as a carrier system for oral delivery of bioactive compounds were demonstrated using model guest molecules.

Effect of Lecithin on the Spontaneous Crystallization of Enzymatically Synthesized Short-Chain Amylose Molecules into Spherical Microparticles.

Here, we report a facile and effective one-pot approach to prepare uniform amylose-based polymeric microparticles (PMPs) through enzymatic synthesis of short-chain amylose (SCA) followed by spontaneous self-assembly of the SCA in the presence of lecithin. The effect of lecithin on nucleation and growth kinetics of amylose microparticles was investigated by monitoring the turbidity of reaction solution and the size of particles over the course of the self-assembly process. The results suggest that lecithin played a critical role in controlling the self-assembly kinetics to form uniform amylose microparticles through steric stabilization of the growing particles and diffusion-limited growth effect. The crystallinity of amylose microparticles was not affected by lecithin, implying that lecithin did not disrupt the crystal structure within the particle and would mainly be present on the surface of the microparticles. Considering its biodegradable and biocompatible nature, the amylose-based microparticles would find a range of useful applications in the area of food, cosmetics, medicine, chromatography and other related materials sciences.