Cold Atmospheric Plasma-Assisted Deposition of SiO x Nanocoatings to Enhance Stability of Pharmaceutical Tablets

Oral pharmaceutical formulations require long-term physicochemical stability to preserve therapeutic efficacy and maintain consistent drug quality across diverse storage and distribution environments. However, maintaining the performance of moisture-sensitive formulations in harsh and variable environments remains a persistent challenge. Recent advances in nanocoating technologies have generated significant interest as next-generation strategies to improve the stability and long-term shelf life of oral pharmaceutical formulations, yet challenges in coating efficiency, scalability, and conformal deposition on complex tablet geometries remain. Here, we report a scalable cold atmospheric plasma (CAP)-assisted approach for the direct and conformal deposition of silicon oxide (SiOx) thin-film nanocoatings to enhance moisture barrier performance and extend tablet shelf life, using amoxicillin tablets as a model formulation. A systematic optimization of plasma scan speed and nozzle-to-substrate distance enabled uniform SiOx deposition while minimizing thermal exposure to the tablet. The optimized SiOx nanocoating was comprehensively characterized to evaluate the long-term moisture barrier performance and stability under accelerated aging conditions. Compared with pristine tablets, SiOx-nanocoated tablets exhibited significantly enhanced stability, retaining over 50% of their initial chemical structure, crystallinity, and antibiotic content for up to 16 days under elevated temperature and humidity (75% RH, 40 °C). Furthermore, the coated tablets maintained broad-spectrum antibacterial activity against Staphylococcus aureus and Escherichia coli for 8 days, extending functional performance by 6 days relative to pristine controls while preserving cytocompatibility throughout the exposure period. Overall, this work demonstrates a scalable, conformal, and low-thermal-load plasma nanocoating strategy that substantially enhances the stability and shelf life of moisture-sensitive pharmaceutical tablets, offering a promising alternative for reliable drug protection in demanding storage and distribution environments.