Single-Step Solvent Evaporation Via Spray-Drying for the Production of Ph-Sensitive Polymeric Nanospheres for
Ana Maria Lenz Cardoso1, Bruna Aparecida Souza Machado2, Silvia Stanisçuaski Guterres1
1Programa de Pós-Graduação Em Farmácia, Faculdade de Farmácia, Universidade Federal da Bahia, Rua Barão de Jeremoabo, 147, Salvador, BA, 40170-115, Brasil.
Abstract:
Polymeric nanospheres are promising drug delivery systems capable of controlling the release of active molecules. However, their inherent colloidal instability necessitates the use of drying techniques to enhance physicochemical stability and microbial resistance. However, conventional multi-step production processes hinder industrial-scale-up due to increased complexity and longer processing times. This work aimed to develop a single-step spray-drying process to obtain Eudragit® L100 nanospheres in powder form, thereby eliminating the need for traditional solvent evaporation, and to investigate the effects of incorporating these nanospheres into hydroxyethyl cellulose gels for dermatological applications. Eudragit® L100 was selected for its controlled release at approximately pH 6.00, facilitating delivery to specific areas, particularly on barrier-disrupted skin. Nanospheres were produced via nanoprecipitation followed by direct spray-drying to reduce production time. The nanosuspension and redispersed dried formulations were characterized by particle size, polydispersity index, morphology, and zeta potential. Before drying, the nanospheres had an average size (Z-average) of 114 nm and a polydispersity index (PdI) of 0.19 and successfully preserved their properties after a single drying step (Z-average = 140 nm and PdI = 0.2). Zeta potential was altered (p < 0.05) but remained high (-23 to -17 mV), indicating electrostatic stabilization. Gel formulations exhibited dose-dependent pseudoplastic behavior, with consistency decreasing proportionally to nanosphere concentration. Finally, moderate to strong correlations were found between rheology and textural analysis. This single-step solvent removal methodology represents a significant manufacturing advancement, offering reduced processing time and costs. The pH-responsive nanospheres showed excellent redispersibility and gel compatibility, establishing their potential as carriers for dermatological systems.
