RESUMO
Extrusion, electrospinning, and microdrawing are widely used to create fibrous polymer mats, but these approaches offer limited access to oriented arrays of nanometer-scale fibers with controlled size, shape, and lateral organization. We show that chemical vapor polymerization can be performed on surfaces coated with thin films of liquid crystals to synthesize organized assemblies of end-attached polymer nanofibers. The process uses low concentrations of radical monomers formed initially in the vapor phase and then diffused into the liquid-crystal template. This minimizes monomer-induced changes to the liquid-crystal phase and enables access to nanofiber arrays with complex yet precisely defined structures and compositions. The nanofiber arrays permit tailoring of a wide range of functional properties, including adhesion that depends on nanofiber chirality.
RESUMO
Periodontal disease destroys supporting structures of teeth. However, tissue engineering strategies offer potential to enhance regeneration. Here, the strategies of patterned topography, spatiotemporally controlled growth factor gene delivery, and cell-based therapy to repair bone-periodontal ligament (PDL) interfaces are combined. Micropatterned scaffolds are fabricated for the ligament regions using polycaprolactone (PCL)/polylactic-co-glycolic acid and combined with amorphous PCL scaffolds for the bone region. Scaffolds are modified using chemical vapor deposition, followed by spatially controlled immobilization of vectors encoding either platelet-derived growth factor-BB or bone morphogenetic protein-7, respectively. The scaffolds are seeded with human cells and delivered to large alveolar bone defects in athymic rats. The effects of dual and single gene delivery with and without micropatterning are assessed after 3, 6, and 9 weeks. Gene delivery results in greater bone formation at three weeks. Micropatterning results in regenerated ligamentous tissues similar to native PDL. The combination results in more mature expression of collagen III and periostin, and with elastic moduli of regenerated tissues that are statistically indistinguishable from those of native tissue, while controls are less stiff than native tissues. Thus, controlled scaffold microtopography combined with localized growth factor gene delivery improves the regeneration of periodontal bone-PDL interfaces.
Assuntos
Osso e Ossos/fisiologia , Ligamento Periodontal/fisiologia , Regeneração , Alicerces Teciduais/química , Animais , Becaplermina/genética , Proteína Morfogenética Óssea 7/genética , Células Cultivadas , Técnicas de Transferência de Genes , Humanos , Ácidos Nucleicos Imobilizados/química , Ácidos Nucleicos Imobilizados/farmacologia , Ligamento Periodontal/citologia , Poliésteres/química , Ratos , Ratos Endogâmicos F344 , Ratos Nus , Regeneração/efeitos dos fármacosRESUMO
Polymers prepared by chemical vapor deposition (CVD) polymerization have found broad acceptance in research and industrial applications. However, their intrinsic lack of degradability has limited wider applicability in many areas, such as biomedical devices or regenerative medicine. Herein, we demonstrate, for the first time, a backbone-degradable polymer directly synthesized via CVD. The CVD co-polymerization of [2.2]para-cyclophanes with cyclic ketene acetals, specifically 5,6-benzo-2-methylene-1,3-dioxepane (BMDO), results in well-defined, hydrolytically degradable polymers, as confirmed by FTIR spectroscopy and ellipsometry. The degradation kinetics are dependent on the ratio of ketene acetals to [2.2]para-cyclophanes as well as the hydrophobicity of the films. These coatings address an unmet need in the biomedical polymer field, as they provide access to a wide range of reactive polymer coatings that combine interfacial multifunctionality with degradability.
Assuntos
Acetais/química , Técnicas de Química Sintética/métodos , Éteres Cíclicos/química , Etilenos/química , Cetonas/química , Piperidinas/química , Polimerização , Polímeros/química , Acetais/síntese química , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Ciclização , Éteres Cíclicos/síntese química , Etilenos/síntese química , Cetonas/síntese química , Oxepinas/síntese química , Oxepinas/química , Piperidinas/síntese química , Polímeros/síntese química , VolatilizaçãoRESUMO
Molecules can be immobilized onto biomaterials by a chemical vapor deposition (CVD) coating strategy. Pentafluorophenolester groups react with amine side chains on antibodies, which can selectively immobilize adenoviral vectors for gene delivery of growth factors. These vectors can produce functional proteins within defined regions of biomaterials to produce customizable structures for targeted tissue regeneration.