Mundo, Jorge L. Muriel, et al. Food Research International 137 (2020): 109304.
Challenge: Oil-in-water emulsions are vital delivery systems but prone to breakdown under pH, salt, or temperature stresses. Achieving tailored stability across diverse conditions (e.g., food processing vs. human digestion) is difficult.
Solution: Researchers utilized cationic Poly-L-lysine (PLL) with anionic poly-glutamic acid (PGA) for layer-by-layer (LbL) electrostatic deposition onto lipid droplets in soybean oil-in-water emulsions. Primary droplets were stabilized with quillaja saponin.
Key Results:
· PLL successfully formed cationic layers on lipid droplets. PLL enabled precise modulation of droplet surface charge (ζ-potential), crucial for targeted emulsion behavior.
· The primary emulsion showed the best tolerance to various environmental conditions, while the secondary emulsion (PLL coating) showed the worst, indicating that electrostatic deposition should only be used to obtain specific functions.
· Salt-Responsive Detachment: PLL detached from droplet surfaces at high salt concentrations due to electrostatic screening.
· Smart Functionality: This detachment offers a unique benefit - emulsions can be designed to switch functionality (e.g., cationic during storage, becoming anionic upon salt exposure in the body).
Conclusion: PLL proves vital for engineering "smart" emulsions. Its salt-triggered detachment offers a unique strategy to create stimuli-responsive systems with switchable functionality, ideal for applications like food or pharmaceuticals requiring environment-specific behavior.