Development and Characterization of Lyophilized Chondroitin Sulfate-Loaded Solid Lipid Nanoparticles: Encapsulation Efficiency and Stability

This study explores the development and characterization of lyophilized chondroitin sulfate (CHON)-loaded solid lipid nanoparticles (SLN) as an innovative platform for advanced drug delivery. Solid lipid nanoparticles are increasingly recognized for their biocompatibility, their ability to encapsulate diverse compounds, their capacity to enhance drug stability, their bioavailability, and their therapeutic efficacy. CHON, a naturally occurring glycosaminoglycan with anti-inflammatory and regenerative properties, was integrated into SLN formulations using the hot microemulsion technique. Two formulations (SLN-1 and SLN-2) were produced and optimized by evaluating critical physicochemical properties such as particle size, zeta potential, encapsulation efficiency (EE%), and stability. The lyophilization process, with the addition of various cryoprotectants, revealed trehalose to be the most effective agent in maintaining nanoparticle integrity and functional properties. Morphological analyses using transmission electron microscopy (TEM) and atomic force microscopy (AFM) confirmed the dimensions of the nanoscales and their structural uniformity. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) revealed minimal excipient interaction with CHON, ensuring formulation stability. Stability studies under different environmental conditions highlighted that SLN-2 is the most stable formulation, maintaining superior encapsulation efficiency (≥88%) and particle size consistency over time. These findings underscore the potential of CHON-loaded SLNs as promising candidates for targeted, sustained-release therapies in the treatment of inflammatory and degenerative diseases.