Mechanistic insights into galantamine adsorption on SBA‐16 mesoporous silica: Kinetic and isotherm analysis

Abstract

SBA-16 mesoporous silica particles (MSPs) with a cage-like architecture were synthesized and optimized for adsorption and controlled release of the BCS Class I drug galantamine hydrobromide. Optimized synthesis conditions produced monodisperse particle size (403 ± 26 nm, PDI 0.42) with high surface area (443 ± 38 m2/g), pore volume (0.236 ± 0.019 cm³/g), and pore radius (1.89 ± 0.02 nm), enabling substantial drug loading (35.5 ± 3.6%) and entrapment efficiency (71 ± 7.3%). Solid-state analyses (DSC, P-XRD, TGA) confirmed drug amorphization within the mesoporous matrix while preserving structural integrity. Adsorption Isotherm data fitted well to the Freundlich isotherm, suggesting heterogeneous surface interactions and multilayer adsorption. Adsorption kinetics at 298, 308, and 318 K showed rapid uptake (8–12 h) and were best described by the nonlinear pseudo-second-order and Elovich model, with fitted equilibrium capacities closely matching experimental values, indicating diffusion-influenced physisorption. Intraparticle diffusion analysis revealed multi-step uptake with significant boundary layer contribution. Kinetic thermodynamic parameters (Ea = 17.9 ± 3.94 kJ mol−1, ΔH‡ =15.3 ± 3.97 kJ mol−1, and ΔS‡= −248 ± 12.9 J mol−1 K−1) supported a physisorption-driven process with a moderate energy barrier and an ordered activated state. In vitro drug release exhibited a biphasic pattern with sustained release up to 24 h. Drug release kinetics followed first-order and Kopcha models, while the Korsmeyer-Peppas exponent (n = 0.423) confirmed Fickian diffusion. These findings establish SBA-16 MSPs as effective carriers, linking diffusion-governed adsorption behavior to controlled drug release performance of a BCS Class I drug.