Systematic Study of Ciprofloxacin Release from Lipid-Based Nanocarriers

Background/Objectives: Lipid-based nanocarriers have emerged as promising systems for improving the delivery of poorly soluble drugs by enhancing stability, bioavailability, and controlled release. This work aimed to formulate solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) containing ciprofloxacin (CIP) using solvent-free procedures. Methods: The systems were extensively characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM) to study the nanoparticles in the solid state. Furthermore, in vitro drug release was evaluated, and mathematical modeling was applied to analyze the resulting release kinetics. Additionally, storage stability was assessed at 4 °C and 25 °C over a period of 8 months. Results: The results indicated that SLN with an average size of ~50 nm (SLN 50) and NLC with mean diameters of ~25, 50, and 100 nm (NLC 25, NLC 50 and NLC 100 respectively) were successfully prepared. DLS measurements showed narrow particle size distributions (PdI ≤ 0.2) and negative zeta potentials ranging from -3.7 to -7.7 mV. Encapsulation efficiencies were remarkably high for most systems, reaching ~98% for SLN 50, NLC 50, and NLC 100, while the smallest formulation (NLC 25) showed a lower efficiency (~80%). Both TEM and AFM confirmed the formation of spherical nanoscale structures consistent with the sizes determined by DLS. Release studies revealed a strong influence of particle size on kinetics: NLC 25 exhibited rapid release (~95% within 30 min), whereas NLC 100 showed a sustained profile (<20% after 6 h). Dissolution profiles were accurately described by the Lumped-Gonzo kinetic model (R² > 0.98), enabling estimation of dissolution efficiency. Conclusions: These findings confirm that lipid-based nanocarriers can be engineered to precisely control CIP release.