Development of novel biopolymer-based dendritic nanocomplexes for encapsulation of phenolic bioactive compounds: a proof-of-concept study

Authors: XUE, JINGYI - University Of Connecticut; Luo, Yaguang - Sunny; BALASUBRAMANIAN, RINDHALAKSHMI - University Of Connecticut; UPADHYAY, ABHINAV - University Of Connecticut; LI, ZHENSHUN - University Of Connecticut; LUO, YANGCHAO - University Of Connecticut

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2021
Publication Date: 6/23/2021
Citation: Xue, J., Luo, Y., Balasubramanian, R., Upadhyay, A., Li, Z., Luo, Y. 2021. Development of novel biopolymer-based dendritic nanocomplexes for encapsulation of phenolic bioactive compounds: a proof-of-concept study. Food Hydrocolloids. 120:106987. https://doi.org/10.1016/j.foodhyd.2021.106987.
DOI: https://doi.org/10.1016/j.foodhyd.2021.106987

Interpretive Summary: Phytoglycogen is a natural nanoscale dendrimer that has unique structural features to harbor bioactive compounds. However, its strong hydrophilicity limits its applications with hydrophobic molecules. In this study, we explored possibility of modifying phytoglycogen with valeric acid and further interacting with zein to form a novel nanocomplex. Hydrophobic bioactive compounds, eugenol and thymol, were successfully encapsulated by this newly formed phytoglycogen-zein complex. This encapsulation further improved the bioactivity of eugenol and thymol, including higher antioxidant activity and stronger antibacterial efficacy. Research findings benefit the food industry by providing a new nanocomplex and method to improve antioxidant and antibacterial applications.

Technical Abstract: Phytoglycogen (PG) is a food-derived and glycogen-like nanoscale dendrimer. While its unique dendritic nanostructures offer promising structural features to harbor bioactive compounds, the strong hydrophilicity limits its applications for encapsulating lipophilic molecules. Here, we report a proof of concept study to modify PG with valeric acid (VAPG) and further interact with zein to form a novel nanocomplexes for encapsulating hydrophobic antibacterial compounds. To avoid the use of toxic organic solvent, zein was solubilized and partially hydrolyzed by heating in 1 M NaOH at 90 °C or above for at least 4 min. Bioactive compound, thymol and eugenol was each co-solubilized with zein under above alkaline condition, followed by addition of PG and then neutralization by citric acid to induce the pH-driven self-assembly of nanocomplexes for encapsulation. Dynamic light scattering measurements indicated that the as prepared nanocomplexes had small particle size (66 nm) with narrow polydispersity and high zeta potential (-44 mV). Morphological observation revealed that these nanocomplexes had spherical shape and uniform size distribution. Both eugenol- and thymol-loaded VAPG nanocomplexes exhibited significantly improved bioactivity, including higher antioxidant activity and stronger antibacterial efficacy, compared with un-encapsulated compounds and PG nanocomplexes. Our findings demonstrated an innovative strategy to develop dendritic nanoparticles from food biopolymers without using organic solvents or synthetic chemicals. The potential of these nanocomplexes as carriers for lipophilic and phenolic antimicrobial compounds opens up new avenues for nanotechnology-enabled approaches to ensure food safety and quality.