L-Arginine And L-Phenylalanine Based Poly (Ester Amide)S, Their Synthesis, Characterization, Formulations And Applications As Gene Delivery Vectors And Tissue Engineering Scaffolds

Abstract

A family of water soluble and positively charged L-arginine based poly (ester amide)s (Arg-PEAs) was synthesized by solution polycondensation. These biodegradable Arg-PEAs consist of 3 nontoxic building blocks: L-arginine, diols and dicarboxylic acids. The Arg-PEAs were prepared by the reaction of tetra-p- toluenesulfonic acids salts of bis-(L-arginine) [alpha], [omega]-alkylene diesters and di-pnitrophenyl esters of dicarboxylic acids. Optimal conditions of the monomers and polymers synthesis were investigated, and the monomers and Arg-PEAs were chemically characterized. Arg-PEAs were found to have good solubility in water and many other polar solvents. . Arg-PEAs were evaluated by many biological assays for the gene delivery applications. Structure-function relationship of the Arg-PEAs revealed that changing the number of methylene groups in the diol or/and diacid segment could finely tune the hydrophobic and cationic properties of the Arg-PEAs, and then affect the gene delivery efficiency. MTT assay showed that all the prepared Arg-PEAs and Arg-PEA/DNA complexes were non-toxic to the cell lines even at very large doses. Some of Arg-PEAs showed comparable or higher transfection efficiency than the commercial transfection agents, Superfect® and Lipofectamine2000®. Based on the above results, a new generation of Arg-PEAs, oligoethylene glycols and L-arginine based poly (ether ester amide)s (Arg-PEEAs) were developed. The new Arg-PEEAs had more flexible chain due to the introduction of oligoethylene glycols. Structure-function relationship of the Arg-PEEAs was intensively studied. MTT assay showed that all the and Arg-PEEA/DNA complexes were non-toxic to the cell lines, primary cells and stem cells even at very large doses. The Arg-PEEAs expanded the gene transfection from cell lines to primary cells/stem cells, and showed comparable or higher transfection efficiency than the commercial transfection agents, Superfect® and Lipofectamine2000®. Arg-PEAs with double bond functionality (Arg-UPEAs) could be photocrosslinked with Pluronic- diacrylate (Pluronic-DA) to form cationic hybrid hydrogels. The physicochemical and mechanical properties of the hybrid hydrogels were studied. The fibroblast and endothelial cells were cultured on the hybrid hydrogel surface and inside the hydrogel, respectively. The results indicated that the introduction of ArgUPEAs could significantly increase the cell attachment performance on hydrogel surface and viability inside the hydrogel. Some new L-phenylalanine based poly (ester amide)s (Phe-PEA) or derivatives were developed as the coating materials causing low inflammatory response. One example is the block copolymer of Phe-PEA and poly ([epsilon] -caprolactone) (PCL) [PEAb-PCL], another example is the L-Arginine and L-phenylalanine based hybrid poly (ester amide)s (Arg-Phe-PEAs). The new biomaterials were characterized and studied the cellular responses, such as cell attachment and macrophage inflammatory response. The results indicated that they could promote the cell attachment and cause very low inflammatory response.