Fabrication and characterisation of novel protein-polysaccharide biopolymer based nanoparticles for iron delivery

OBJECTIVE: To utilise naturally sourced proteins and polysaccharides to develop and char-acterize a novel carrier system for oral iron delivery. MATERIALS AND METHODS: The milk protein whey protein isolate (WPI) was used as a protein component together with varying ratios of the polysaccharide chitosan (low molecular weight; Cl, medium molecular weight; Cm, and high molecular weight, Ch). Batches of the protein-polysaccharide blend nanoparticles entrapping ferrous iron (FeSO4) and correspond-ing iron free (BLANK) controls were prepared for final analysis as follows: WPI-Cl-Fe, WPI-Cl-BLANK, WPI-Cm-Fe, WPI-Cm-BLANK, WPI-Ch-Fe, and WPI-Ch-BLANK. Particle size and zeta potential were determined using a Malvern Zetasizer-Nano. Nanoparticle iron up-take in simulated gastro-intestinal fluid was compared using the intestinal cell line caco-2, using intracellular ferritin protein as a measure of iron absorption and FeSO4 as control. Cel-lular cytotoxity was determined by MTT assay (48 and 72 hour time-points). Microbial bioa-vailability to formulated iron was determined by comparative of growth measurement at 600 nm. RESULTS: WPI-chitosan nanoparticles (entrapping iron and BLANK) were all within submi-cron size range (< 600 nm). All formulations were non-toxic at test concentrations. Caco-2 iron uptake experiments revealed variable absorption uptake demonstrating an effect of chi-tosan molecular weight on nanoparticle uptake; WPI-Cm-Fe demonstrated iron absorption equivalent to free FeSO4 (P ≤ 0.05). Importantly, a decreased iron bioavailability for bacteria was observed with nanoparticle entrapped iron as compared to free FeSO4. CONCLUSION: This study demonstrates for the first time the development of a novel pro-tein-polysaccharide iron delivery system for nutritional applications. High absorption with re-duced bioavailability to microbes presents interesting avenues for further development.