Niharika Walia | ALES Graduate Seminar

Date(s) - 20/06/2019
9:30 am - 10:30 am
318J Agriculture/Forestry Centre (AgFor), Agriculture/Forestry Centre, Edmonton AB

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Niharika Walia. This seminar is open to the general public to attend.
Thesis Topic: Pea Protein based Nanoemulsions for Delivery of Vitamin D: Fabrication, Stability and In vitro Study using Caco-2 Cells

Seminar Abstract:

In North America, a significant population is vitamin D deficient due to insufficient sunlight exposure in winters. Increasing research has shown that vitamin D, apart from its skeletal functions, also has potential to lower the risk of chronic diseases such as diabetes mellitus, cardiovascular diseases, cancers, etc. However, vitamin D exhibits low bioavailability due to its poor solubility in human gut. This research aims to develop pea protein stabilized nanoemulsions as vitamin D delivery systems for improved vitamin absorption.

In the first study, nanoemulsions stabilized by pea protein were developed using a high-energy approach by high-pressure homogenization treatment. The nanoemulsions exhibited controllable sizes ranging from 170 to 350 nm, good stability with zeta-potential value of around -25 mV, and high vitamin D encapsulation efficiency of 93-96%. Using Caco-2 cell model, cellular uptake efficiency of small sized nanoemulsions (233 nm) was found to be ~ 2.5 folds higher (p < 0.05) than large sized nanoemulsions (350 nm). Interestingly, protein-based nanoemulsions exhibited significantly higher cellular uptake than emulsions prepared using a combination of protein and lecithin. The transport efficiency of vitamin D across Caco-2 cells for small sized nanoemulsions (233 nm) was ~ 5.3 times greater than free vitamin D suspension.

In the second study, a low-energy approach was used to prepare a complex nanoemulsion, formed by a combination of tween 80 and pea protein by spontaneous emulsification method, which does not rely on high-energy equipment and thus, the processing can be more convenient,  cost effective and environmentally sustainable. Tween 80 (3% w/v) was used as a small molecular surfactant to prepare nanoemulsion droplets of 134.8 nm, followed by addition of pea protein (3% w/v), resulting in the formation of complex nanoemulsions with particle size of 207.7 nm. Infrared spectroscopy was used to investigate the effect of tween 80 on protein conformation, and tween 80 showed only partial denaturation of pea protein molecules. A “clusters on string” structure was proposed for the complex nanoemulsions, which featured tween 80 stabilized micelles clustered together on pea protein polymeric chains. The in vitro assays using Caco-2 cells indicated that both nanoemulsions stabilized by tween 80 alone and the complex nanoemulsion could efficiently improve vitamin D uptake by ≥ 2.5 folds (p < 0.05) as compared to free vitamin D suspension. Interestingly, the transport efficiency of vitamin D across Caco-2 cells for complex nanoemulsions was 5.6 folds higher than free vitamin D suspension and 2.3 folds higher than nanoemulsions stabilized by tween alone.

Overall, these nanoemulsions demonstrated efficient encapsulation, cellular uptake and transport of vitamin D using Caco-2 cell model to simulate absorption through intestinal epithelium. Such protein-based nanoemulsions may allow more efficient vitamin D delivery to improve the status of vitamin deficiencies in aged population and in areas with less sun exposure.


MSc with Dr. Lingyun Chen

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