Application of nanocoatings produced by electrostatic layer-by-layer self-assembling to improve the physicochemical properties of drugs and excipients / Schalk Johannes Strydom

• Main Author: Strydom, Schalk Johannes
• Language: en
• Published: 2015
• Online Access: http://hdl.handle.net/10394/15588

Layer-by-layer (LbL) is a self-assembly technique, proven to be a simplified method for the modification of material surfaces. The LbL multilayers are formed due to electrostatic attraction between opposite charged polymers. Substrates which can be utilised using this technique include dyes, enzymes, drugs and cells. In this study which comprise of three separate LbL studies, 1) compactible cellulose was nanocoated by means of LbL, 2) poly(amidoamine) dendrimer mediated synthesis of silver sulfadiazine nanoparticles and 3) four poorly water soluble drugs were nanocoated, i.e. furosemide, isoxyl, rifampicin, paclitaxel. In the first study Kraft softwood fibers was nanocoated using the LbL technique. This technique turned non-flowing, non-compacting cellulose into powders with positive tabletting properties which can be used in direct compression in the tabletting process. The cellulose microfibers which were coated with four PSS/PVP bilayers, display the best compaction properties. One of the major advantages of nanocoating is that the process adds less than 1% to the weight of the fibres. This process proved to be environmental friendly due to the type of materials used and the quantity. In the second study silver sulfadiazine (limited aqueous solubility) was used to synthesize highly soluble AgSD nanoparticles. In this particular study the nanoparticles were stabilized against crystal growth by LbL coating. PAMAM dendrimers were used to coat the particles. The dendrimers served as solubility enhancer for this poorly water soluble antibiotic. This study illustrated that nanotechnology based dosage forms can be create and that PAMAM dendrimers were crucial to the success of this dosage form. In the third study, a LbL nanocoat of chitosan and chondroitin sulfate was self-assembled step-wise onto drug nanoparticles. Furosemide, isoxyl, rifampin and paclitaxel were chosen to prepare these nanoparticles. All four of them display poor water solubility properties. Although the nanocoating reduced the dissolution proportional to the coat thickness, it still dissolved faster than the commercially available micronized powders of the drugs. Also this LbL nanocoating stabilizes the small particles against crystal growth and aggregation in suspension. The release patterns of the drugs were superior to that of the raw materials. This study proved that LbL coating can improve the performance of poorly water soluble drugs. === PhD (Pharmaceutics), North-West University, Potchefstroom Campus, 2015