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

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 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 degrees 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 against foodborne human pathogens (Listeria monocytogenes and Salmonella Enteritidis), 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.