Preparation and investigation of solid lipid nanoparticles for drug delivery

•12 newly formulated SLNs were synthesized via microemulsion method.•Size and surface properties of SLNs were controlled by changing the composition.•Drug entrapment and release capacities of SLNs have been investigated.•Methylene blue have been used as model molecule in the drug incorporation studies.•Surface charge densities were correlated with entrapment/release capacities of SLNs.

Solid lipid nanoparticles (SLN), a promising drug delivery vehicle, offer an alternative system to traditional colloidal carriers. In our study 12 new SLN formulations were fabricated via the “microemulsion (ME) method”, each leading to a different SLN size and composition. This method is a relatively easy technique and involves biocompatible conditions. Stearic acid has been used as lipid material of which the ratio is kept under 4% to prevent particle growth. Particle size and surface properties of the synthesized SLNs were controlled using various combinations of emulsifiers such as lithocholic acid, Pluronic F127, Tween 20, lecithin and butanol. Furthermore, the mean size of the particles was adjusted by changing the ME:water ratio in the dilution step which is independent from composition. It was found that most of the SLNs were in the colloidal size range (below 100 nm) and spherical in shape, which provides high surface area to exploit, as an alternative adsorptive drug carrier system. Also, the surface charge density values of SLNs were calculated by considering size and zeta potential values which then helps in understanding the surface potential of particles. MB was chosen as a model molecule and entrapped on the surface of SLNs after the preparation, to determine the loading capacities and release efficiencies. As such, SLNs have been successfully produced which have controllable drug entrapment efficiency and release capacity according to the chosen combination of emulsifiers and dilution ratio. Thus, this study contributes to the improvement of alternative drug delivery systems with biocompatible and stable newly formulated SLNs.

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