(393f) Continuous Polymer Coating of Nanoparticles, Submicron Particles and Drug Crystals By Hollow Fiber Cooling Crystallization

Nanoparticle-based drug delivery systems are of significant interest in controlled release of drugs, delivery of anticancer drugs and imaging agents to tumors, tuberculosis treatment and as non-viral gene delivery vehicles. To develop controlled release of the drug as well as to protect the drug from demanding environments, appropriate coatings are employed on the drug nanoparticles. Conventional methods for coating or encapsulating micron–sized and nanoparticles utilize dry or wet approaches. Dry methods include physical vapor deposition, plasma treatment, chemical vapor deposition and pyrolysis of polymeric organic materials. Wet methods cover sol-gel processes, emulsification and solvent evaporation techniques.  Supercritical fluid (SCF) processes such as Rapid Expansion of Supercritical Solutions (RESS), Supercritical Anti-Solvent (SAS), and Gas Anti-Solvent (GAS) processes employing supercritical CO₂ are alternative methods for nanoparticle coating or encapsulation of ultrafine particles. These SCF-based processes have many shortcomings. Some processes require demanding operating conditions and often suffer from low polymer solubility. Most of these techniques are also batch processes. Fluidized bed-based processes, which can be continuous, face difficulties with nanoparticles caused by van der Waals and other interparticle forces. In all such processes, scale-up is also quite demanding. 

We have developed a technique for continuous polymer coating of nanoparticles that is easily scalable. This technique utilizes the solid hollow fiber cooling crystallization (SHFCC) method developed earlier in our laboratory to provide polymer coating on the host particle. We have now demonstrated the utility of this continuous technique for developing thin polymeric coatings on silica nanoparticles (SNPs), silica-based submicron particles, and crystals of the drug Griseofulvin. The size of the primary SNPs used was 12 nm; the size of the submicron silica particles was 550 nm. The polymers used for coating using the SHFCC technique were Eudragit RL 100 and PLGA.