Multifunctional powder makeup with salicylic acid-cationic guar gum nanoplexes for acne-prone skin

This study aimed to develop and characterize a multifunctional powder-based makeup incorporating nanoplexes (NPx) composed of salicylic acid (SA) and cationic guar gum (CGG) for potential application in the treatment of acne vulgaris.

NPx were synthesized via ionic interaction between negatively charged SA and positively charged CGG using a 2ᵏ factorial experimental design to optimize formulation parameters. The resulting NPx were characterized in terms of particle size, polydispersity index (PDI), zeta potential and encapsulation efficiency using dynamic and electrophoretic light scattering. Additional analyses included FTIR, Raman spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The optimized NPx were then incorporated into a powder makeup base, also developed via factorial design, and evaluated for rheological and physicomechanical properties. Cell viability was assessed in HaCaT keratinocytes.

The optimized NPx formulation exhibited high encapsulation efficiency (83% ± 1.01%), with an average particle size of 854 nm, a PDI of 0.885 and a positive zeta potential of 16.87 mV, indicating colloidal moderate stability and a positive surface charge compatible with dermal adhesion potential. Structural and thermal characterization confirmed successful encapsulation and compatibility of the components. The final powder makeup formulation showed suitable flow properties (Carr's index: 33.391% ± 1.85%; Hausner ratio: 1.50 ± 0.06; angle of repose: 59.87° ± 4.90°), and HaCaT keratinocyte assays demonstrated biocompatibility of Makeup, NPx and Makeup+NPx, with preserved metabolic activity and no cytotoxic effects at the tested concentrations, making it viable for cosmetic application while potentially delivering therapeutic effects.

This work demonstrates that the integration of SA-CGG NPx into a powder makeup base represents a promising strategy for acne-prone skin care and prevention. The resulting dermocosmetic product combines controlled SA delivery with aesthetic functionality, offering a multifunctional approach that supports skin balance while providing cosmetic benefits.