Topical delivery performance of Pickering emulsions stabilized by differently charged spirulina protein isolate/Chitosan composite particles.

Pickering emulsions, stabilized by particulate particles, have emerged as a promising vehicle for topical delivery. Herein, Pickering emulsions stabilized by differently charged spirulina protein isolate - chitosan (SC) composite particles were studied for effective topical delivery of α-Bisabolol (ABS). The composite particles were synthesized via electrostatic assembly of spirulina protein isolate (SPI) and chitosan (CS), and their surface charge was assessed using zeta potential measurements. The Pickering emulsions stabilized by SC composite particles with different charges were all stable over 30 days and had a high encapsulation efficiency for ABS. In vitro skin permeation study revealed that positively charged emulsions significantly increased ABS retention within the skin, predominantly in the stratum corneum layer. The underlying delivery mechanism was further explored using attenuated total reflection Fourier transform infrared spectroscopy. Lastly, the influence of particle concentration and oil phase volume fraction on the topical delivery efficiency was conducted to optimize the Pickering formulations. This study provides insight into the role of particle charge in enhancing topical delivery of Pickering emulsions.