(701f) Preparation of Colloidal Microcapsules for Controlled Drug Delivery Systems

Nanoparticles (NPs) are one of the most used and studied materials in nanotechnology. Among the other usages, nanoparticles can also be used as a drug delivery agent in biomedical applications. They can be exploited as a sensor in the diagnosis and a delivery agent in the treatment of diseases. NPs can be synthesized by using a variety of constituents, primarily metallic, polymer, composite and lipid.. Solid lipid nanoparticles (SLNs), prepared using various physiological lipids, emulsifiers and water, have been used since the 1990s as colloidal nanocarrier systems, either in combination with or as an alternative to liposomes, emulsions and polymeric nanoparticles [1]. Possessing adjustable release kinetic, determined by the method of synthesis used, its level of biocompatibility, its stability and the degree to which active materials may be encapsulated within its structure, SLNs are ideal for use within the body and may be administered via different routes (parenteral, topical, ocular, etc.). There are several methods that could be utilized to synthesize SLNs, including high pressure homogenization, high shear homogenization, etc. However, if the incorporation of selected compounds is intended, particularly drugs, genes, proteins and other biomolecules, methods such as high pressure or high shear homogenization which create harsh environments for the material, need to be avoided. By using microemulsion method, the nanoparticle formulations of interest can be prepared in vials rapidly, reproducibly and cost effectively in a two-step process involving only mild operating temperatures. Moreover, the uniform nanoparticles produced become more biocompatible due to the elimination of organic solvent use during its preparation. Furthermore, the solubilization properties of hot microemulsions enable SLNs to be loaded with various drugs and is particularly useful for drugs with poor water solubility.

As well as NPs are being used in several areas including medical and pharmaceutical individually, more versatile systems can be established via self-assembly of NPs. Colloidal microcapsules are one of the most interested part of these self-assembled structures whose shell side are composed of nanoparticles [2]. Layer-by-layer method (LbL) is one of the most used methods in the production of self-assembled structures. These self-assembled structures, independent from their single form, possess attractive properties such as high stability, enhanced functionality and increased loading capacity. Additionally, using pharmaceutically active ingredients such as drug crystals or drug loaded nanoparticles as the core material of colloidal microcapsules provides controlled release of the encapsulated material with the help of shell layers [3]. In this study, novel self-assembled colloidal microcapsules by using Ibuprofen crystals or CaCO₃ nanoparticles as core material and SLNs as shell material were prepared by using LbL method. The performance of establishing the layers was monitored by measuring the change of zeta-potential values. Also the self-assembled structures were visualized with SEM. Controlled drug release from the microcapsules was monitored by using UV-visible spectroscopy. Due to several advantageous properties such as being composed of physiologically related lipids, possessing properties like small and adjustable structure, high surface area, enhanced stability, stimuli-responsivity and increased encapsulation efficiency, these unique systems will be an ideal alternative to the conventional nanocarriers, which are especially used in pharmaceutical and biomedical applications as controlled drug delivery agents.

[1] Mehnert, W., Mader, K., 2001, Advanced Drug Delivery Reviews, 47, 165-196.

[2] Bae, J. et al. 2013, Current Organic Chemistry, 17, 3-13.

[3] Sukhorukov, G. B. et al. 2004, Langmuir, 20, 3398-3406.