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1.
Adv Healthc Mater ; 7(11): e1701485, 2018 06.
Artículo en Inglés | MEDLINE | ID: mdl-29635761

RESUMEN

Hybrid nanomaterials have shown great potential in regenerative medicine due to the unique opportunities to customize materials properties for effectively controlling cellular growth. The peptide nanofiber-mediated auto-oxidative polymerization of dopamine, resulting in stable aqueous dispersions of polydopamine-coated peptide hybrid nanofibers, is demonstrated. The catechol residues of the polydopamine coating on the hybrid nanofibers are accessible and provide a platform for introducing functionalities in a pH-responsive polymer analogous reaction, which is demonstrated using a boronic acid modified fluorophore. The resulting hybrid nanofibers exhibit attractive properties in their cellular interactions: they enhance neuronal cell adhesion, nerve fiber growth, and growth cone area, thus providing great potential in regenerative medicine. Furthermore, the facile modification by pH-responsive supramolecular polymer analog reactions allows tailoring the functional properties of the hybrid nanofibers in a reversible fashion.


Asunto(s)
Materiales Biocompatibles Revestidos , Conos de Crecimiento/metabolismo , Indoles , Nanofibras/química , Fibras Nerviosas/metabolismo , Polímeros , Animales , Adhesión Celular , Materiales Biocompatibles Revestidos/química , Materiales Biocompatibles Revestidos/farmacología , Indoles/química , Indoles/farmacología , Ratones , Péptidos/química , Péptidos/farmacología , Polimerizacion , Polímeros/química , Polímeros/farmacología
2.
Acta Biomater ; 7(8): 3158-69, 2011 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21550424

RESUMEN

Bone is an organic-inorganic composite which has hierarchical structuring that leads to high strength and toughness. The nanostructure of bone consists of nanocrystals of hydroxyapatite embedded and aligned within the interstices of collagen fibrils. This unique nanostructure leads to exceptional properties, both mechanical and biological, making it difficult to emulate bone properties without having a bone-like nanostructured material. A primary goal of our group's work is to use biomimetic processing techniques that lead to bone-like structures. In our prior studies, we demonstrated that intrafibrillar mineralization of porous collagen sponges, leading to a bone-like nanostructure, can be achieved using a polymer-induced liquid precursor (PILP) mineralization process. The objective of this study was to investigate the use of this polymer-directed crystallization process to mineralize dense collagen substrates. To examine collagen scaffolds that truly represent the dense-packed matrix of bone, manatee bone was demineralized to isolate its collagen matrix, consisting of a dense, lamellar osteonal microstructure. This biogenic collagen scaffold was then remineralized using polyaspartate to direct the mineralization process through an amorphous precursor pathway. The various conditions investigated included polymer molecular weight, substrate dimension and mineralization time. Mineral penetration depths of up to 100 µms were achieved using this PILP process, compared to no penetration with only surface precipitates observed for the conventional crystallization process. Electron microscopy, wide-angle X-ray diffraction and thermal analysis were used to characterize the resulting hydroxyapatite/collagen composites. These studies demonstrate that the original interpenetrating bone nanostructure and osteonal microstructure could be recovered in a biogenic matrix using the PILP process.


Asunto(s)
Biomimética/métodos , Sustitutos de Huesos/farmacología , Trasplante Óseo , Calcificación Fisiológica/efectos de los fármacos , Colágeno/metabolismo , Animales , Huesos/citología , Huesos/efectos de los fármacos , Huesos/ultraestructura , Análisis Diferencial Térmico , Minerales/química , Polimerizacion/efectos de los fármacos , Polímeros/farmacología , Termogravimetría , Trichechus , Difracción de Rayos X
3.
Polymers (Basel) ; 3(1): 10-35, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-22328971

RESUMEN

The nanostructure of bone has been replicated using a polymer-induced liquid-precursor (PILP) mineralization process. This polymer-mediated crystallization process yields intrafibrillar mineralization of collagen with uniaxially-oriented hydroxyapatite crystals. The process-directing agent, an anionic polymer which we propose mimics the acidic non-collagenous proteins associated with bone formation, sequesters calcium and phosphate ions to form amorphous precursor droplets that can infiltrate the interstices of collagen fibrils. In search of a polymeric agent that produces the highest mineral content in the shortest time, we have studied the influence of various acidic polymers on the in vitro mineralization of collagen scaffolds via the PILP process. Among the polymers investigated were poly-L aspartic acid (PASP), poly-L-glutamic acid (PGLU), polyvinylphosphonic acid (PVPA), and polyacrylic acid (PAA). Our data indicate that PASP and the combination of PGLU/PASP formed stable mineralization solutions, and yielded nano-structured composites with the highest mineral content. Such studies contribute to our goal of preparing biomimetic bone graft substitutes with composition and structure that mimic bone.

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