Development and modeling of Silk Sericin Gentamicin microparticles as a drug delivery system

Systemic administration of antibiotics is commonly used to treat infections during wound healing; however, its extensive use has contributed to the emergence of antibiotic-resistant bacteria. The local and controlled delivery of antibiotics is an alternative method for mitigating systemic exposure. This study focused on developing and modeling sericin-gentamicin microparticles as drug delivery systems using a spray-drying process. Sericin was selected due to its biocompatibility, biodegradability, moisture-retention capacity, and the presence of functional groups that facilitate drug-polymer interactions, making it a promising alternative to conventional synthetic polymers. The effects of compound concentration, airflow, and solution flow on drug content and microparticle size distribution were analyzed and modeled. Optimal encapsulation conditions were achieved with an airflow of 400 L/h and a solution flow of 1.5 mL/min, using a formulation composed of 2 % (w/v) sericin and 1 % (w/v) gentamicin. Successful drug encapsulation was confirmed by Fourier transform infrared spectroscopy (FTIR), which suggested electrostatic interactions and hydrogen bonding, potentially promoting conformational changes. Thermogravimetric analysis (TGA) demonstrated enhanced thermal stability of the optimal microparticles (second decomposition peak at 332 °C), while morphological analysis revealed spherical microparticles with a uniform size distribution (3.38 ± 1.29 μm). Drug release studies indicated an initial rapid release, followed by a sustained release phase governed by diffusion mechanisms with a diffusion coefficient of 1.1749 × 10-15 m2/s. These findings contribute to the design of drug delivery systems, highlighting its potential as a future alternative for localized antibiotic delivery in wound healing contexts.