Nanotechnology in citrus essential oil

From waste to wealth: Fabrication of ligand-decorated capsules loaded with citrus essential oil for colon-specific functionality.

Introduction
Citrus essential oil (CEO) is a natural extract from citrus fresh peel. It shows multiple biological activities such as anti-inflammatory effect after oral administration. However, CEO is rapidly absorbed in the small intestine and undergoes metabolization in the liver. It may also irritate the mucous layer of the gastrointestinal tract. Encapsulation within indigestible protein particles holds premises to prevent CEO absorption in the small intestine and delivery into the large intestine, where CEO can execute anti-inflammatory effects. Colon delivery may as well enable targeting malignant cells for treatment of patients with certain types of cancer. Zein is a prolamin protein and has been widely used in delivery of bioactive compounds, which is an ideal carrier for CEO.

Aim
We expect to develop a colon-specific CEO-loaded capsules and mechanistically explain its anti-inflammatory functionality.

Approach
CEO will be encapsulated within zein particles via a simple and scale-upable method, i.e. desolvation (i.e. replacing ethanol with water). Then, the CEO-loaded zein particles will be decorated with folic acid (and other phenolic acids) to target the cancerous cells and/or enhance antibacterial ability of CEO. Folate receptors are highly expressed on malignant cells and activated macrophages, providing a route for cellular uptake of the CEO-loaded particles. In addition, folic acid can help to deliver nanoparticles into the cytoplasm of bacteria. After measurement of particle size, surface charge and encapsulation efficacy, in vitro gastrointestinal digestibility of CEO-loaded and folic acid-conjugated particles will be assessed. With the well-characterized functional particles, some beneficial biofunctions could be explored. For example, the antibacterial effects of the particles on harmful gut bacteria and probiotics could be tested and the cellular delivery of CEO-loaded zein particles could be examined in Caco-2 cells using fluorescence-activated cell sorting.