Synthesis and Characterization of Magnetic Polymeric Nanospheres for Biomedical Applications
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Synthesis and Characterization of Magnetic Polymeric Nanospheres for Biomedical Applications D. K. Kim1, M. Mikhaylova1, M. Toprak1, A. Guyou2, Y. K. Jeong3, and M. Muhammed1 1
Materials Chemistry Division, Royal Institute of Technology, SE-100 44 Stockholm, Sweden 2 Institut des Science et Techniques de Grenoble, France 3 KICET (Korea Institute of Ceramic Engineering and Technology) 153-801, Seoul, Korea
ABSTRACT Entrapment of proteins in biodegradable nanospheres has been widely investigated as a technique to produce sustained release formulations for protein or anti-cancer drugs administration. Amphiphilic PLLA-mPEG diblock copolymer was prepared by ring opening polymerization (ROP) to form polymeric nanoparticles with a core-shell structure. The main encapsulation technique done is a water-in-oil-in-water (w/o/w) solvent evaporation technique. Here, protein was encapsulated using a newly developed water-in-oil emulsion-solvent diffusion technique. This technique leads to the formation of an emulsion combined with the immediate precipitation of the PLLA-mPEG. This phenomenon is caused by the diffusion of the polymer solvent to an external organic phase. INTRODUCTION Resent research shows that the use of polymeric nanoparticles as drug carriers is receiving an increasing interest for biomedical applications. The development of suitable delivery systems for protein-based drugs with high molecular weights and short half-lives is a current interest. In addition, nanoparticles have a number of potential applications in drug delivery as well as gene therapy applications. Biodegradable polymers have functional properties such as being hydrolysable at temperatures up to 50 °C over a period that varies from several months up to years. Therefore, they have been the focus of intense research over the past two decades due to their potential applications in biomedical fields. Also, toxicity of the degradation products of these degradable polymers is an important parameter for any potential biomedical applications. Mainly, degradable polymers of aliphatic polyesters have specific advantageous properties. Among the plentiful polyester groups, polylactide has shown to be the most functional category of biodegradable polyesters. Usually, Land D, L- lactic acid can be easily produced based on strains of a lactobacillus and metabolism of all animals and microorganism. Therefore, the polylactides are nontoxic biodegradable and not immunogenic. It has been shown that mPEG coating of nanospheres provides protection against interaction with the blood components, which induce removal of the foreign particles from the blood. It prolongs, therefore, the circulation of these nanoparticles in the blood stream. In consequence, thus coated nanospheres may function as circulation “depots” for the administrated drugs. Among hydrophilic polymers, mPEG is considered to be non-toxic and was approved by the Food and Drug Administration (FDA, USA) for internal use in humans.[1] A vast amount of research work has been devoted to a better un
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