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1.
Acta Biomater ; 69: 183-195, 2018 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-29378324

RESUMO

This work is the first reporting the use of layer-by-layer to produce adhesive free-standing (FS) films fully produced using natural-based macromolecules: chitosan (CHI), alginate (ALG) and sulfated levan (L-S). The deposition conditions of the natural polymers were studied through zeta potential measurements and quartz crystal microbalance with dissipation monitoring analysis. The properties of the FS films were evaluated and compared with the control ones composed of only CHI and ALG in order to assess the influence of levan polysaccharide introduced in the multilayers. Tensile tests, dynamic mechanical analysis and single lap shear strength tests were performed to evaluate the mechanical properties of the prepared FS films. The presence of L-S conferred both higher tensile strength and shear strength to the developed FS membranes. The results showed an adhesion strength 4 times higher than the control (CHI/ALG) FS films demonstrating the adhesive character of the FS films containing L-S. Morphological and topography studies were carried out revealing that the crosslinking reaction granted the L-S based FS film with a higher roughness and surface homogeneity. Preliminary biological assays were performed by cultivating myoblasts cells on the surface of the produced FS films. Both crosslinked and uncrosslinked FS films containing L-S were cytocompatible and myoconductive. STATEMENT OF SIGNIFICANCE: Sutures remain as the "gold standard" for wound closure and bleeding control; however they still have limitations such as, high infection rate, inconvenience in handling, and concern over possible transmission of blood-borne disease through the use of needles. One of the challenges of tissue engineering consist on the design and development of biocompatible tissue adhesives and sealants with high adhesion properties to repair or attach devices to tissues. In this work, the introduction of sulfated levan (L-S) on multilayered free-standing membranes was proposed to confer adhesive properties. Moreover, the films were myoconductive even in the absence of crosslinking just by the presence of L-S. This study provides a promising strategy to develop biological adhesives and for cardiac tissue engineering applications.


Assuntos
Alginatos/química , Bandagens , Quitosana/química , Frutanos/química , Teste de Materiais , Membranas Artificiais , Adesivos Teciduais/química , Adesão Celular , Linhagem Celular , Humanos
2.
Tissue Eng Part A ; 23(23-24): 1502-1533, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28903686

RESUMO

This review is focused on the use of membranes for the specific application of bone regeneration. The first section focuses on the relevance of membranes in this context and what are the specifications that they should possess to improve the regeneration of bone. Afterward, several techniques to engineer bone membranes by using "bulk"-like methods are discussed, where different parameters to induce bone formation are disclosed in a way to have desirable structural and functional properties. Subsequently, the production of nanostructured membranes using a bottom-up approach is discussed by highlighting the main advances in the field of bone regeneration. Primordial importance is given to the promotion of osteoconductive and osteoinductive capability during the membrane design. Whenever possible, the films prepared using different techniques are compared in terms of handability, bone guiding ability, osteoinductivity, adequate mechanical properties, or biodegradability. A last chapter contemplates membranes only composed by cells, disclosing their potential to regenerate bone.


Assuntos
Regeneração Óssea , Membranas Artificiais , Osteogênese , Engenharia Tecidual/métodos , Animais , Humanos
3.
Adv Healthc Mater ; 6(15)2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28371516

RESUMO

Inspired by native extracellular matrix (ECM) together with the multilevel architecture observed in nature, a material which topography recapitulates topographic features of the ECM and the internal architecture mimics the biological materials organization is engineered. The nanopatterned design along the XY plane is combined with a nanostructured organization along the Z axis on freestanding membranes prepared by layer-by-layer deposition of chitosan and chondroitin sulfate. Cellular behavior is monitored using two different mammalian cell lines, fibroblasts (L929) and myoblasts (C2C12), in order to perceive the response to topography. Viability, proliferation, and morphology of L929 are sensitively controlled by topography; also differentiation of C2C12 into myotubes is influenced by the presence of nanogrooves. This kind of nanopatterned structure has also been associated with strong cellular alignment. To the best of the knowledge, it is the first time that such a straightforward and inexpensive strategy is proposed to produce nanopatterned freestanding multilayer membranes. Controlling cellular alignment plays a critical role in many human tissues, such as muscles, nerves, or blood vessels, so these membranes can be potentially useful in specific tissue regeneration strategies.


Assuntos
Materiais Biomiméticos/síntese química , Polaridade Celular/fisiologia , Tamanho Celular , Matriz Extracelular/química , Fibroblastos/fisiologia , Membranas Artificiais , Impressão Tridimensional , Fibroblastos/citologia , Humanos , Teste de Materiais , Mioblastos/citologia , Mioblastos/fisiologia , Propriedades de Superfície , Engenharia Tecidual/métodos
4.
Biomacromolecules ; 17(4): 1347-57, 2016 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-26957012

RESUMO

The lack of knowledge on the degradation of layer-by-layer structures is one of the causes hindering its translation to preclinical assays. The enzymatic degradation of chitosan/hyaluronic acid films in the form of ultrathin films, freestanding membranes, and microcapsules was studied resorting to hyaluronidase. The reduction of the thickness of ultrathin films was dependent on the hyaluronidase concentration, leading to thickness and topography variations. Freestanding membranes exhibited accelerated weight loss up to 120 h in the presence of the enzyme, achieving complete degradation. Microcapsules with around 5 µm loaded simultaneously with FITC-BSA and hyaluronidase showed that the coencapsulation of such enzyme and protein mixture led to a FITC-BSA release four times higher than in the absence of hyaluronidase. The results suggest that the degradation of LbL devices may be tuned via embedded enzymes, namely, in the controlled release of active agents in biomedical applications.


Assuntos
Cápsulas/química , Quitosana/metabolismo , Preparações de Ação Retardada/síntese química , Sistemas de Liberação de Medicamentos/métodos , Ácido Hialurônico/metabolismo , Hialuronoglucosaminidase/metabolismo
5.
Soft Matter ; 12(4): 1200-9, 2016 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-26617221

RESUMO

The design of self-standing multilayered structures based on biopolymers has been attracting increasing interest due to their potential in the biomedical field. However, their use has been limited due to their gel-like properties. Herein, we report the combination of covalent and ionic cross-linking, using natural and non-cytotoxic cross-linkers, such as genipin and calcium chloride (CaCl2). Combining both cross-linking types the mechanical properties of the multilayers increased and the water uptake ability decreased. The ionic cross-linking of multilayered chitosan (CHI)-alginate (ALG) films led to freestanding membranes with multiple interesting properties, such as: improved mechanical strength, calcium-induced adhesion and shape memory ability. The use of CaCl2 also offered the possibility of reversibly switching all of these properties by simple immersion in a chelate solution. We attribute the switch-ability of the mechanical properties, shape memory ability and the propensity for induced-adhesion to the ionic cross-linking of the multilayers. These findings suggested the potential of the developed polysaccharide freestanding membranes in a plethora of research fields, including in biomedical and biotechnological fields.


Assuntos
Alginatos/química , Quitosana/química , Membranas Artificiais , Adesividade , Cálcio/química , Reagentes de Ligações Cruzadas/química , Resistência à Tração
6.
Langmuir ; 31(41): 11318-28, 2015 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-26421873

RESUMO

We investigated the pH-dependent properties of multilayered films made of chitosan (CHI) and alginate (ALG) and focused on their postassembly response to different pH environments using a quartz crystal microbalance with dissipation monitoring (QCM-D), swelling studies, ζ potential measurements, and dynamic mechanical analysis (DMA). In an acidic environment, the multilayers presented lower dissipation values and, consequently, higher moduli when compared with the values obtained for the pH used during the assembly (5.5). When the multilayers were exposed to alkaline environments, the opposite behavior occurred. These results were further corroborated by the ability of this multilayered system to exhibit a reversible swelling-deswelling behavior within the pH range from 3 to 9. The changes in the physicochemical properties of the multilayer system were gradual and different from those of individual solubilized polyelectrolytes. This behavior is related to electrostatic interactions between the ionizable groups combined with hydrogen bonding and hydrophobic interactions. Beyond the pH range of 3-9, the multilayers were stabilized by genipin cross-linking. The multilayered films also became more rigid while the pH responsiveness conferred by the ionizable moieties of the polyelectrolytes was preserved. This work demonstrates the versatility and feasibility of LbL methodology to generate inherently pH stimulus-responsive nanostructured films. Surface functionalization using pH responsiveness endows several biomedical applications with abilities such as drug delivery, diagnostics, microfluidics, biosensing, and biomimetic implantable membranes.


Assuntos
Alginatos/química , Quitosana/química , Eletrólitos/química , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Técnicas de Microbalança de Cristal de Quartzo , Eletricidade Estática
7.
Bioconjug Chem ; 26(8): 1571-81, 2015 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-26106949

RESUMO

Injectable hyaluronic acid (HA)-based hydrogels compose a promising class of materials for tissue engineering and regenerative medicine applications. However, their limited mechanical properties restrict the potential range of application. In this study, cellulose nanocrystals (CNCs) were employed as nanofillers in a fully biobased strategy for the production of reinforced HA nanocomposite hydrogels. Herein we report the development of a new class of injectable hydrogels composed of adipic acid dihydrazide-modified HA (ADH-HA) and aldehyde-modified HA (a-HA) reinforced with varying contents of aldehyde-modified CNCs (a-CNCs). The obtained hydrogels were characterized in terms of internal morphology, mechanical properties, swelling, and degradation behavior in the presence of hyaluronidase. Our findings suggest that the incorporation of a-CNCs in the hydrogel resulted in a more organized and compact network structure and led to stiffer hydrogels (maximum storage modulus, E', of 152.4 kPa for 0.25 wt % a-CNCs content) with improvements of E' up to 135% in comparison to unfilled hydrogels. In general, increased amounts of a-CNCs led to lower equilibrium swelling ratios and higher resistance to degradation. The biological performance of the developed nanocomposites was assessed toward human adipose derived stem cells (hASCs). HA-CNCs nanocomposite hydrogels exhibited preferential cell supportive properties in in vitro culture conditions due to higher structural integrity and potential interaction of microenvironmental cues with CNC's sulfate groups. hASCs encapsulated in HA-CNCs hydrogels demonstrated the ability to spread within the volume of gels and exhibited pronounced proliferative activity. Together, these results demonstrate that the proposed strategy is a valuable toolbox for fine-tuning the structural, biomechanical, and biochemical properties of injectable HA hydrogels, expanding their potential range of application in the biomedical field.


Assuntos
Tecido Adiposo/citologia , Celulose/química , Ácido Hialurônico/química , Hidrogéis/administração & dosagem , Células-Tronco Mesenquimais/citologia , Nanopartículas/química , Engenharia Tecidual , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Humanos , Hidrogéis/química , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier
8.
Macromol Rapid Commun ; 36(4): 405-12, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25639465

RESUMO

This work investigates the influence of the hydration level on the molecular mobility and glass transition dynamics of freestanding chitosan/alginate (CHT/ALG) nanolayered systems. Nonconventional dynamic mechanical analysis identifies two relaxation processes assigned to the α-relaxation of the two biopolymers, respectively, CHT and ALG, when immersed in water/ethanol mixtures. This phenomenon explains the shape memory properties of the multilayered systems induced by hydration, thus constituting promising smart materials that would be of paramount importance in a plethora of research fields, including in the biomedical and biotechnological fields.


Assuntos
Nanoestruturas/química , Polímeros/química , Alginatos/química , Quitosana/química , Etanol/química , Vidro/química , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Água/química
9.
Acta Biomater ; 15: 139-49, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25575853

RESUMO

Free-standing (FS) membranes have increasing applications in the biomedical field as drug delivery systems for wound healing and tissue engineering. Here, we studied the potential of free-standing membranes made by the layer-by-layer assembly of chitosan and alginate to be used as a simple biomimetic system of the periosteum. The design of a periosteum-like membrane implies the elaboration of a thick membrane suitable for both muscle and bone formation. Our aim was to produce well-defined ∼50 µm thick polysaccharide membranes that could be easily manipulated, were mechanically resistant, and would enable both myogenesis and osteogenesis in vitro and in vivo. The membranes were chemically crosslinked to improve their mechanical properties. Crosslinking chemistry was followed via Fourier transform infrared spectroscopy and the mechanical properties of the membranes were assessed using dynamic mechanical analysis. The loading and release of the potent osteoinductive growth factor bone morphogenetic protein 2 (BMP-2) inside and outside of the FS membrane was followed by fluorescence spectroscopy in a physiological buffer over 1 month. The myogenic and osteogenic potentials of the membranes in vitro were assessed using BMP-2-responsive skeletal myoblasts. Finally, their osteoinductive properties in vivo were studied in a preliminary experiment using a mouse ectopic model. Our results showed that the more crosslinked FS membranes enabled a more efficient myoblast differentiation in myotubes. In addition, we showed that a tunable amount of BMP-2 can be loaded into and subsequently released from the membranes, depending on the crosslinking degree and the initial BMP-2 concentration in solution. Only the more crosslinked membranes were found to be osteoinductive in vivo. These polysaccharide-based membranes have strong potential as a periosteum-mimetic scaffold for bone tissue regeneration.


Assuntos
Membranas Artificiais , Desenvolvimento Muscular/efeitos dos fármacos , Mioblastos/citologia , Osseointegração/efeitos dos fármacos , Polissacarídeos/farmacologia , Animais , Proteína Morfogenética Óssea 2/farmacologia , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Reagentes de Ligações Cruzadas/farmacologia , Humanos , Camundongos , Microscopia Eletrônica de Varredura , Mioblastos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Proteínas Recombinantes/farmacologia , Imagem com Lapso de Tempo , Fator de Crescimento Transformador beta/farmacologia , Microtomografia por Raio-X
10.
J Mater Chem B ; 3(22): 4555-4568, 2015 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-32262400

RESUMO

Tissues presenting continuous variations of properties in one direction have inspired the development of functional graded materials. In this work, we developed a new facile method for the development of continuous gradients in chitosan (CHIT) and alginate (ALG) polyelectrolyte multilayers (PEMs) obtained layer-by-layer based on the gradual dipping of CHIT/ALG coated glass slides in genipin solution. Stiffness gradients were produced in the cm scale by varying the reaction time with genipin. Quartz crystal microbalance, colorimetric measurements, trypan blue assay, attenuated total reflection-Fourier transform infrared spectroscopy, swelling ability, water contact angle and dynamic mechanical analysis (DMA) were used to find suitable conditions for the stiffness gradient. The PEMs can be successfully built up and cross-linked with genipin to yield surfaces with uniform physicochemical properties or with gradients of different physicochemical properties. It was found that a large reduction in the hydrophobic nature of the CHIT/ALG PEMs could be produced with higher cross-linking reaction times, regardless of the decrease in their swelling ability. Moreover, the mechanical properties were evaluated using an innovative and non-conventional DMA to monitor the cross-linking reaction in situ. The results confirm an enhancement on the tensile storage modulus with increasing reaction times from 60 to 140 MPa. In another original DMA testing protocol the local compression storage modulus was also measured directly on the films along the stiffness gradient, with results consistent with the tensile tests obtained on the freestanding membranes with different cross-linking degrees. The in vitro biological performance demonstrates that L929 adhered and spread more in the stiffer regions. This work demonstrates the versatility and feasibility of the LbL methodology to generate functional biomimetic surfaces with tuned mechanical and physicochemical properties, which hold great promise for the study of cell-substrate interactions.

11.
J Tissue Eng Regen Med ; 9(5): 550-63, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-23303734

RESUMO

Due to the limited self-repair capacity of cartilage, regenerative medicine therapies for the treatment of cartilage defects must use a significant amount of cells, preferably applied using a hydrogel system that can promise their delivery and functionality at the specific site. This paper discusses the potential use of κ-carrageenan hydrogels for the delivery of stem cells obtained from adipose tissue in the treatment of cartilage tissue defects. The developed hydrogels were produced by an ionotropic gelation method and human adipose stem cells (hASCs) were encapsulated in 1.5% w/v κ-carrageenan solution at a cell density of 5 × 10(6) cells/ml. The results from the analysis of the cell-encapsulating hydrogels, cultured for up to 21 days, indicated that κ-carrageenan hydrogels support the viability, proliferation and chondrogenic differentiation of hASCs. Additionally, the mechanical analysis demonstrated an increase in stiffness and viscoelastic properties of κ-carrageenan gels with their encapsulated cells with increasing time in culture with chondrogenic medium. These results allowed the conclusion that κ-carrageenan exhibits properties that enable the in vitro functionality of encapsulated hASCs and thus may provide the basis for new successful approaches for the treatment of cartilage defects.


Assuntos
Adipócitos/citologia , Carragenina/administração & dosagem , Condrócitos/citologia , Condrogênese , Hidrogéis/química , Células-Tronco/citologia , Tecido Adiposo/citologia , Animais , Cartilagem/citologia , Técnicas de Cultura de Células , Diferenciação Celular , Linhagem Celular , Fibroblastos/metabolismo , Humanos , Camundongos , Estresse Mecânico , Temperatura , Engenharia Tecidual/métodos
12.
Biomacromolecules ; 15(10): 3817-26, 2014 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-25244323

RESUMO

Engineering metabolically demanding tissues requires the supply of nutrients, oxygen, and removal of metabolic byproducts, as well as adequate mechanical properties. In this work, we propose the development of chitosan (CHIT)/alginate (ALG) freestanding membranes fabricated by layer-by-layer (LbL) assembly. CHIT/ALG membranes were cross-linked with genipin at a concentration of 1 mg·mL(-1) or 5 mg·mL(-1). Mass transport properties of glucose and oxygen were evaluated on the freestanding membranes. The diffusion of glucose and oxygen decreases with increasing cross-linking concentration. Mechanical properties were also evaluated in physiological-simulated conditions. Increasing cross-linking density leads to an increase of storage modulus, Young modulus, and ultimate tensile strength, but to a decrease in the maximum hydrostatic pressure. The in vitro biological performance demonstrates that cross-linked films are more favorable for cell adhesion. This work demonstrates the versatility and feasibility of LbL assembly to generate nanostructured constructs with tunable permeability, mechanical, and biological properties.


Assuntos
Alginatos/química , Quitosana/química , Membranas/química , Alginatos/metabolismo , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/metabolismo , Adesão Celular/fisiologia , Células Cultivadas , Quitosana/metabolismo , Reagentes de Ligações Cruzadas/química , Fibroblastos/metabolismo , Ácido Glucurônico/química , Ácido Glucurônico/metabolismo , Ácidos Hexurônicos/química , Ácidos Hexurônicos/metabolismo , Iridoides/química , Iridoides/metabolismo , Membranas/metabolismo , Membranas Artificiais , Camundongos , Nanoestruturas/química , Permeabilidade , Resistência à Tração
13.
Acta Biomater ; 10(10): 4175-85, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24905935

RESUMO

Osteogenic differentiation is a tightly regulated process dependent on the stimuli provided by the micro-environment. Silicon-substituted materials are known to have an influence on the osteogenic phenotype of undifferentiated and bone-derived cells. This study aims to investigate the bioactivity profile as well as the mechanical properties of a blend of starch and poly-caprolactone (SPCL) polymeric fiber mesh scaffolds functionalized with silanol (Si-OH) groups as key features for bone tissue engineering strategies. The scaffolds were made from SPCL by a wet spinning technique. A calcium silicate solution was used as a non-solvent to develop an in situ functionalization with Si-OH groups in a single-step approach. We also explored the relevance of silicon incorporated in SPCL-Si scaffolds to the in vitro osteogenic process of goat bone marrow stromal cells (gBMSCs) with and without osteogenic supplements in the culture medium. We hypothesized that SPCL-Si scaffolds could act as physical and chemical millieus to induce per se the osteogenic differentiation of gBMSCs. Results show that osteogenic differentiation of gBMSCs and the production of a mineralized extracellular matrix on bioactive SPCL-Si scaffolds occur for up to 2weeks, even in the absence of osteogenic supplements in the culture medium. The omission of media supplements to induce osteogenic differentiation is a promising feature towards simplified and cost-effective cell culturing procedures of a potential bioengineered product, and concomitant translation into the clinical field. Thus, the present work demonstrates that SPCL-Si scaffolds and their intrinsic properties sustain gBMSC osteogenic features in vitro, even in the absence of osteogenic supplements to the culture medium, and show great potential for bone regeneration strategies.


Assuntos
Células da Medula Óssea/metabolismo , Regeneração Óssea , Calcificação Fisiológica , Diferenciação Celular , Osteogênese , Silanos/química , Alicerces Teciduais/química , Animais , Células da Medula Óssea/citologia , Compostos de Cálcio/química , Células Cultivadas , Cabras , Poliésteres/química , Silicatos/química , Amido/química , Células Estromais/citologia , Células Estromais/metabolismo
14.
Biomacromolecules ; 15(2): 635-43, 2014 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-24417502

RESUMO

In this work, carbon nanofibers were used as doping material to develop a highly conductive chitosan-based composite. Scaffolds based on chitosan only and chitosan/carbon composites were prepared by precipitation. Carbon nanofibers were homogeneously dispersed throughout the chitosan matrix, and the composite scaffold was highly porous with fully interconnected pores. Chitosan/carbon scaffolds had an elastic modulus of 28.1 ± 3.3 KPa, similar to that measured for rat myocardium, and excellent electrical properties, with a conductivity of 0.25 ± 0.09 S/m. The scaffolds were seeded with neonatal rat heart cells and cultured for up to 14 days, without electrical stimulation. After 14 days of culture, the scaffold pores throughout the construct volume were filled with cells. The metabolic activity of cells in chitosan/carbon constructs was significantly higher as compared to cells in chitosan scaffolds. The incorporation of carbon nanofibers also led to increased expression of cardiac-specific genes involved in muscle contraction and electrical coupling. This study demonstrates that the incorporation of carbon nanofibers into porous chitosan scaffolds improved the properties of cardiac tissue constructs, presumably through enhanced transmission of electrical signals between the cells.


Assuntos
Carbono/metabolismo , Quitosana/metabolismo , Miócitos Cardíacos/citologia , Engenharia Tecidual , Alicerces Teciduais/química , Animais , Carbono/química , Células Cultivadas , Quitosana/química , Condutividade Elétrica , Miócitos Cardíacos/química , Miócitos Cardíacos/metabolismo , Ratos , Ratos Sprague-Dawley
15.
Mater Sci Eng C Mater Biol Appl ; 33(7): 4480-3, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23910369

RESUMO

Fundamental aspects of biomineralization may be important in order to understand and improve calcification onto the surface of biomaterials. The biomineralization process is mainly followed in vitro by assessing the evolution of the apatite layer that is formed upon immersion of the material in Simulated Body Fluid (SBF). In this work we propose an innovative methodology to monitor apatite deposition by looking at the evolution of the mechanical/viscoelastic properties of the sample while immersed in SBF, using non-conventional dynamic mechanical analysis (DMA) performed under distinct displacement amplitudes (d). The biomimetic biomineralization process in composite membranes of chitosan (CTS) with Bioglass® (BG) was followed by measuring the change of the storage modulus, E', and the loss factor, tan δ, at 37 °C and in SBF, both online (d=10 µm and d=30 µm) and offline (d=0 µm). The online experiments revealed that the E' decreased continuously up in the first hours of immersion in SBF that should be related to the dissolution of BG particles. After that, an increase of the stiffness was verified due to the apatite deposition. SEM/EDS observations upon 24h of immersion in SBF showed higher development of apatite deposition with increasing displacement amplitude.


Assuntos
Materiais Biocompatíveis/farmacologia , Cerâmica/farmacologia , Quitosana/farmacologia , Fenômenos Mecânicos/efeitos dos fármacos , Membranas Artificiais , Minerais/farmacologia , Líquidos Corporais/química , Módulo de Elasticidade/efeitos dos fármacos , Humanos , Espectrometria por Raios X
16.
Biomacromolecules ; 14(5): 1653-60, 2013 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-23590116

RESUMO

Free-standing films have increasing applications in the biomedical field as drug delivery systems for wound healing and tissue engineering. Here, we prepared free-standing membranes by the layer-by-layer assembly of chitosan and alginate, two widely used biomaterials. Our aim was to produce a thick membrane and to study the permeation of model drugs and the adhesion of muscle cells. We first defined the optimal growth conditions in terms of pH and alginate concentration. The membranes could be easily detached from polystyrene or polypropylene substrate without any postprocessing step. The dry thickness was varied over a large range from 4 to 35 µm. A 2-fold swelling was observed by confocal microscopy when they were immersed in PBS. In addition, we quantified the permeation of model drugs (fluorescent dextrans) through the free-standing membrane, which depended on the dextran molecular weight. Finally, we showed that myoblast cells exhibited a preferential adhesion on the alginate-ending membrane as compared to the chitosan-ending membrane or to the substrate side.


Assuntos
Alginatos/química , Quitosana/química , Eletrólitos/química , Membranas Artificiais , Mioblastos/efeitos dos fármacos , Animais , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Dextranos , Corantes Fluorescentes , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Camundongos , Peso Molecular , Mioblastos/citologia , Permeabilidade , Polipropilenos , Poliestirenos , Alicerces Teciduais , Molhabilidade
17.
J Mech Behav Biomed Mater ; 20: 173-83, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23466499

RESUMO

A new family of biodegradable polymer/bioactive glass (BG) composite materials has emerged based on the availability of nano-sized bioactive particles. Such novel biocomposites can have enhanced performance, in terms of mechanical properties and bioactivity, and they can be designed to be used in bone regeneration approaches. In this work, membranes of chitosan (CTS) and chitosan with bioactive glass (BG) both micron and nano sized particles (CTS/µBG, CTS/nBG, respectively) were prepared by solvent casting. Microstructural and mechanical properties were evaluated in order to compare the effects of the incorporation of micro (µBG) and nano (nBG) particles in the chitosan matrix. In vitro bioactivity tests were performed to characterize the apatite layer that is formed on the surface of the material after being immersed in simulated body fluid (SBF). The biomineralization process on the biomaterials was also followed using non-conventional dynamic mechanical analysis (DMA), both online and offline. In such DMA experiments, the change in the storage modulus, E', and the loss factor, tan δ, were measured as a function of the immersion time in SBF. The results demonstrated that CTS/nBG membranes possess enhanced mechanical properties and higher bioactivity in comparison with the CTS/µBG membranes. Such results suggest the potential of nBG for the development of bioactive composites for bone regeneration applications.


Assuntos
Apatitas/síntese química , Líquidos Corporais/química , Substitutos Ósseos/síntese química , Calcificação Fisiológica , Quitosana/química , Membranas Artificiais , Nanopartículas/química , Animais , Materiais Biomiméticos/química , Vidro/química , Humanos , Teste de Materiais , Nanopartículas/ultraestrutura , Tamanho da Partícula
18.
Dent Mater ; 29(4): 427-36, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23422419

RESUMO

OBJECTIVE: In the treatment of periodontal defects, composite membranes might be applied to protect the injured area and simultaneously stimulate tissue regeneration. This work describes the development and characterization of poly(d,l-lactic acid)/Bioglass® (PDLLA/BG) composite membranes with asymmetric bioactivity. We hypothesized that the presence of BG microparticles could enhance structural and osteoconductivity performance of pure PDLLA membranes. METHODS: The membranes were prepared by an adjusted solvent casting method that promoted a non-uniform distribution of the inorganic component along the membrane thickness. In vitro bioactive behavior (precipitation of an apatite layer upon immersion in simulated body fluid, SBF), SEM observation, FTIR, swelling, weight loss and mechanical properties of the developed biomaterials were evaluated. Cell behavior on the membranes was assessed using both human bone marrow stromal cells and human periodontal ligament cells. RESULTS: Just the BG rich face of the composite membranes induced the precipitation of bone-like apatite in SBF, indicating that this biomaterial exhibit asymmetric osteoconductive properties. SEM images, DNA content and metabolic activity quantification revealed an improved cell adhesion and proliferation on the composite membranes. Composite membranes also stimulated cell differentiation, mineralization, and production of extracellular matrix and calcium nodules, suggesting the positive effect of adding the bioactive microparticles in the PDLLA matrix. SIGNIFICANCE: The results indicate that the proposed asymmetric PDLLA/BG membranes could have potential to be used in guided tissue regeneration therapies or in orthopedic applications, with improved outcomes.


Assuntos
Materiais Biocompatíveis/síntese química , Regeneração Óssea/fisiologia , Cerâmica/química , Regeneração Tecidual Guiada/instrumentação , Células-Tronco Mesenquimais/citologia , Ligamento Periodontal/citologia , Poliésteres/química , Fosfatase Alcalina/análise , Análise de Variância , Apatitas/química , Cálcio/análise , Técnicas de Cultura de Células , Humanos , Teste de Materiais , Células-Tronco Mesenquimais/metabolismo , Microscopia Eletrônica de Varredura , Ligamento Periodontal/metabolismo , Periodontite/terapia , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Nanomedicine (Lond) ; 8(3): 359-78, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23259755

RESUMO

AIM: The development of novel silk/nano-sized calcium phosphate (silk/nano-CaP) scaffolds with highly dispersed CaP nanoparticles in the silk fibroin (SF) matrix for bone tissue engineering. MATERIALS & METHODS: Nano-CaP was incorporated in a concentrated aqueous SF solution (16 wt.%) by using an in situ synthesis method. The silk/nano-CaP scaffolds were then prepared through a combination of salt-leaching/lyophilization approaches. RESULTS: The CaP particles presented good affinity to SF and their size was inferior to 200 nm when theoretical CaP/silk ratios were between 4 and 16 wt.%, as determined by scanning electron microscopy. The CaP particles displayed a uniform distribution in the scaffolds at both microscopic and macroscopic scales as observed by backscattered scanning electron microscopy and micro-computed tomography, respectively. The prepared scaffolds presented self-mineralization capability and no cytotoxicity confirmed by in vitro bioactivity tests and cell viability assays, respectively. CONCLUSION: These results indicated that the produced silk/nano-CaP scaffolds could be suitable candidates for bone-tissue-engineering applications.


Assuntos
Osso e Ossos/química , Nanopartículas Calcificantes/química , Fosfatos de Cálcio/química , Fibroínas/química , Seda/química , Animais , Materiais Biocompatíveis/química , Bombyx , Nanopartículas Calcificantes/uso terapêutico , Fosfatos de Cálcio/uso terapêutico , Fibroínas/ultraestrutura , Humanos , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Porosidade , Seda/ultraestrutura , Engenharia Tecidual , Alicerces Teciduais/química
20.
Acta Biomater ; 8(11): 4173-80, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22771458

RESUMO

Barrier membranes are used in periodontal applications with the aim of supporting periodontal regeneration by physically blocking migration of epithelial cells. The present work proposes a combination of chitosan (CHT) with bioactive glass nanoparticles (BG-NPs) in order to produce a novel guided tissue and bone regeneration membrane, fabricated by solvent casting. The CHT/BG-NP nanocomposite membranes are characterized in terms of water uptake, in mechanical tests, under simulated physiological conditions and in in vitro bioactivity tests. The addition of BG-NPs to CHT membranes decreased the mechanical potential of these membranes, but on the other hand the bioactivity improved. The membranes containing the BG-NPs induced the precipitation of bone-like apatite in simulated body fluid (SBF). Biological tests were carried out using human periodontal ligament cells and human bone marrow stromal cells. CHT/BG-NP composite membranes promoted cell metabolic activity and mineralization. The results indicate that the CHT/BG-NP composite membrane could potentially be used as a temporary guided tissue regeneration membrane in periodontal regeneration, with the possibility to induce bone regeneration.


Assuntos
Cerâmica/química , Quitosana/farmacologia , Vidro/química , Regeneração Tecidual Guiada Periodontal , Membranas Artificiais , Nanocompostos/química , Nanopartículas/química , Cálcio/metabolismo , DNA/metabolismo , Fluorescência , Humanos , Nanocompostos/ultraestrutura , Nanopartículas/ultraestrutura , Oxazinas/metabolismo , Ligamento Periodontal/efeitos dos fármacos , Ligamento Periodontal/fisiologia , Espectrometria por Raios X , Coloração e Rotulagem , Estresse Mecânico , Água/química , Xantenos/metabolismo
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