RESUMO
This study focused on the synthesis and characterization of poly(ethylene glycol)-poly(D,L-lactide-co-glycolide)-poly(ethylene glycol) tri-block co-polymer (PEG-PDLLG-PEG), and its modification with type-I collagen. To this aim, a PEG-PDLLG-PEG tri-block co-polymer was synthesized in two steps by reacting poly(ethylene glycol)bis(carboxymethyl)ether with thionyl chloride to obtain an acyl-halide-terminated poly(ethylene glycol) and subsequently coupling this compound to hydroxyl-terminated poly(D,L-lactide-co-glycolide) (PDLLG). The new carboxyl endgroups of PEG-PDLLG-PEG were subsequently reacted with N-hydroxysuccinimide (NHS) in the presence of the hetero-bifunctional cross-linking agent dicyclohexylcarbodiimide (DCC) in order to activate the co-polymer for coupling with collagen. PEG-PDLLG-PEG and its activated form PEG-PDLLG-NHS were characterized by Fourier transform infrared (FT-IR) and 1H-NMR spectroscopy. Molecular weights of the polymeric products were determined by SEC. Type-I collagen in phosphate buffer was reacted with PEG-PDLLG-NHS. The resultant product, PEG-PDLLG-Col, was characterized by FT-IR. This biopolymer was used for preparation of a suitable surface for cell growth experiment. To measure the degree of cell proliferation, the films prepared with PDLLG, PEG-PDLLG-NHS and PEG-PDLLG-Col were seeded with L929 mouse fibroblasts. Cell growth was followed by SEM photography and quantitated by the neutral red uptake assay. It was shown that the attachment of collagen significantly increased the number of cells on the co-polymers.
Assuntos
Materiais Biocompatíveis/síntese química , Adesão Celular , Colágeno Tipo I/química , Poliésteres/síntese química , Polietilenoglicóis/síntese química , Animais , Materiais Biocompatíveis/química , Comunicação Celular , Células Cultivadas , Etilenoglicol/química , Fibroblastos/citologia , Fibroblastos/metabolismo , Ácido Láctico/síntese química , Ácido Láctico/química , Espectroscopia de Ressonância Magnética , Camundongos , Poliésteres/química , Polietilenoglicóis/química , Ácido Poliglicólico/síntese química , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Polímeros/síntese química , Polímeros/química , Succinimidas/química , Succinimidas/farmacologiaRESUMO
Poly(DL-lactide-co-glycolide) (PDLLGA) and poly(L-lactide-co-glycolide) (PLLGA) copolymers were prepared by bulk ring opening polymerization of lactide and glycolide and characterized by GPC, FTIR, 1H NMR and DSC. Copolymers with different molar masses at a constant lactide/glycolide ratio were used for preparation of bovine serum albumin (BSA)-loaded microparticles by the double emulsion w/o/w method. The influence of the copolymer molar mass and composition on the microparticle morphology, size, yield, degradation rate, BSA-loading efficiency and BSA release profile were studied. For microparticles prepared from PDLLGA copolymers, a biphasic profile for BSA release was found and for those made from PLLGA copolymers the release profile was typically triphasic; both of them were characterized by high initial burst release. Possible reasons for such behavior are discussed.
Assuntos
Preparações de Ação Retardada/síntese química , Preparações de Ação Retardada/farmacocinética , Ácido Láctico/síntese química , Ácido Láctico/farmacocinética , Tamanho da Partícula , Ácido Poliglicólico/síntese química , Ácido Poliglicólico/farmacocinética , Polímeros/síntese química , Polímeros/farmacocinética , Animais , Bovinos , Química Farmacêutica/métodos , Portadores de Fármacos/síntese química , Portadores de Fármacos/farmacocinética , Emulsões , Glicolatos/síntese química , Glicolatos/farmacocinética , Ácido Láctico/classificação , Ácido Poliglicólico/classificação , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Polímeros/classificação , Soroalbumina Bovina/química , Soroalbumina Bovina/farmacocinética , Tecnologia Farmacêutica/métodosRESUMO
Poly(lactic acid)/poly(glycolic acid)/poly(dimethylsiloxane) (PLGA/TEGOMER) terpolymers have been synthesized by the ring-opening polymerization of L-lactide and glycolide with alpha,omega-amine-terminated poly(dimethylsiloxane) prepolymer, using stannous octoate as a catalyst. The resulting terpolymers were characterized by various analytical techniques including size exclusion chromatography, 1H-nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy, and differential scanning calorimetry. The data showed that the terpolymers presented an amorphous structure. The glass transition temperature decreased with increasing TEGOMER unit content. For in vitro degradation studies, porous films were fabricated using a solvent-casting, particulate leaching technique. Degradation of the PLGA/TEGOMER terpolymer was studied in phosphate-buffered saline at pH 7.4 and 37 degrees C. The degradation was followed by intrinsic viscosity, mass loss, and molecular weight measurements, and 1H-NMR spectroscopy. The mass loss after 55 days was 76% for the PLGA/TEGOMER (71/24/5) sample. Cell growth experiments using Swiss 3T3 fibroblasts demonstrated that PLGA/TEGOMER terpolymer matrices allow the attachment and growth of cells.
