Title: Novel potato protein-polysaccharide nano-formulations for oral nutrient delivery Study Objective(s): Bioactive molecules (minerals, vitamins and phytochemicals) have diverse health promoting effects and are used to supplement diet as nutraceuticals. The potential health benefits of several nutraceuticals are limited by lack of stability, reduced activity and low bioavailability. Nano-formulation presents an appealing means of preserving beneficial characteristics while potentially enhancing absorption and potency. Food derived biopolymers such as proteins and polysaccharides are relatively inexpensive, biocompatible, and already used widely in food/ nutraceutical industries. They thus present an attractive resource to formulate nano-vehicles for stabilisation and delivery of nutraceutical bioactives. The aim of our study was to use novel natural source food derived ingredients to formulate nanocarriers for nutrient delivery applications. Iron was selected as a model nutrient for our initial study since i.) iron has a poor sensory profile ii.) is highly reactive rendering it particularly challenging to formulate iii.) iron deficiency is the most common nutritional deficiency worldwide. Method: Nanocarriers incorporating ferrous sulphate (FeSO4 elemental iron equivalent; Fe) and corresponding iron free (BLANK) were prepared by modified nanoprecipitation method with varying protein : polysaccharide ratios. Batches (4) of nanocarriers were formulated with potato protein isolate (PP, ≥95% protein content) and two varieties of the crustacean derived natural polysaccharide chitosan (chitosan HCL – CH; chitosan oligosaccharide – CO): i.) PP+CH-Fe ii.) PP+CH-BLANK ii.) PP+CO-Fe iv.) PP+CO-BLANK. Nanocarrier iron incorporation efficiency was determined by colourimetric iron detection. Nanocarrier physiochemical characteristics were assessed by particle size, zeta potential and transmission electron microscopy analysis. Cellular uptake was evaluated using the human intestinal cell line caco-2 in simulated gastrointestinal fluid and cytotoxicity was determined in presence of increasing concentrations of BLANK and iron loaded nanocarriers (upto 48 hour time-point). Gut pathogenic microbe access to nanoentrapped iron was determined by comparative of growth measurement at 600 nm. Results: Novel potato protein-chitosan blend nanocarriers were successfully fabricated using our optimised protocol. Nanocarriers demonstrated high iron entrapment efficiency (>80%), rounded morphology and a submicron size range (<500 nm) known to favour intestinal permeability as well as stability. Chitosan HCL as well as chitosan oligosaccharide conferred a net positive surface charge that may promote enhanced interaction and uptake in intestinal enterocytes. Nanocarriers demonstrated intestinal iron absorption (as determined by intracellular ferritin) significantly higher than free FeSO4 control (n = 6, P ≤ 0.05), and were non-toxic under experimental conditions (48 h incubation). A decreased iron bioavailability for pathogenic microbes was observed with nanocarrier entrapped iron as compared to free FeSO4. Conclusions: • We demonstrate for the first time the development of novel potato protein-chitosan blend nanocarriers for formulation and delivery of nutrients and the use of potato protein isolate as a novel biomaterial for food formulation. • High absorption with reduced bioavailability to pathogenic microbes presents interesting avenues for oral nutrient delivery. • Our results using the model nutrient (iron) suggests the potential of these delivery systems for high efficacy nutraceutical product formulations for food, beverages and cosmetic applications. • The delivery system is highly versatile, suitable for a range of nutraceuticals, and supports an ‘all natural’ label claim. Funding: Dr MG Zariwala personal research reserve fund.