RESUMEN
Bacteria are one of the significant causes of infection in the body after scaffold implantation. Effective use of nanotechnology to overcome this problem is an exciting and practical solution. Nanoparticles can cause bacterial degradation by the electrostatic interaction with receptors and cell walls. Simultaneously, the incorporation of antibacterial materials such as zinc and graphene in nanoparticles can further enhance bacterial degradation. In the present study, zinc-doped hydroxyapatite/graphene was synthesized and characterized as a nanocomposite material possessing both antibacterial and bioactive properties for bone tissue engineering. After synthesizing the zinc-doped hydroxyapatite nanoparticles using a mechanochemical process, they were composited with reduced graphene oxide. The nanoparticles and nanocomposite samples were extensively investigated by transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. Their antibacterial behaviors against Escherichia coli and Staphylococcus aureus were studied. The antibacterial properties of hydroxyapatite nanoparticles were found to be improved more than 2.7 and 3.4 times after zinc doping and further compositing with graphene, respectively. In vitro cell assessment was investigated by a cell viability test and alkaline phosphatase activity using mesenchymal stem cells, and the results showed that hydroxyapatite nanoparticles in the culture medium, in addition to non-toxicity, led to enhanced proliferation of bone marrow stem cells. Furthermore, zinc doping in combination with graphene significantly increased alkaline phosphatase activity and proliferation of mesenchymal stem cells. The antibacterial activity along with cell biocompatibility/bioactivity of zinc-doped hydroxyapatite/graphene nanocomposite are the highly desirable and suitable biological properties for bone tissue engineering successfully achieved in this work.
Asunto(s)
Antibacterianos , Células de la Médula Ósea/metabolismo , Huesos/metabolismo , Nanocompuestos/química , Células Madre/metabolismo , Ingeniería de Tejidos , Animales , Antibacterianos/química , Antibacterianos/farmacología , Durapatita/química , Durapatita/farmacología , Escherichia coli/crecimiento & desarrollo , Grafito/química , Grafito/farmacología , Ratones , Staphylococcus aureus/crecimiento & desarrollo , Zinc/química , Zinc/farmacologíaRESUMEN
To mimic the fibrous architecture of collagen, the nanofibrous gelatin scaffolds are fabricated employing a thermally induced phase separation (TIPS) technique. The influences of processing parameters, including polymer concentration and solvent mixture composition on the scaffold microstructure are investigated. However, using the TIPS technique, a limited pore size range is generally obtained. To yield the well-interconnected macroporous structures with equiaxed pores and nanofibrous architectures, the TIPS technique is combined with particulate leaching. The macroporous structure of produced scaffolds duplicates the predefined three-dimensional template structure. The homogenous macrostructure with well-interconnected equiaxed pores and no particular orientation is created. Modulating the size and shape of microspheres has precise control over porosity, pore size, and interconnection of the matrix. Because of the well-interconnected macroporous nanofibrous structure, the useful applications of these scaffolds in the tissue engineering field are expected.
Asunto(s)
Gelatina , Nanofibras , Polímeros , Porosidad , Ingeniería de Tejidos , Andamios del TejidoRESUMEN
Poly(dimethylsiloxane) (PDMS) elastomer is now a well-known material for packaging implantable biomedical micro-devices owing to unique bulk properties such as biocompatibility, low toxicity, excellent rheological properties, good flexibility, and mechanical stability. Despite the desirable bulk characteristics, PDMS is generally regarded as a high-flux material for oxygen and water vapor to penetrate compared with other polymeric barrier materials, which is related to the defect-induced penetration through the packaging coating prepared by the traditional deposition techniques. Besides, its hydrophobic nature causes serious fouling problems and limits the practical application of PDMS-based devices. In this work, the performance of silicone thin films as a packaging layer was improved by the fabrication of the roller-casted multiple thin layers to minimize a defect-induced failure. To confer hydrophilicity and cell fouling resistance, high-density and well-defined poly(oligo(ethylene glycol) methacrylate) (POEGMA) brushes were tethered via the surface-initiated atom transfer radical polymerization (SI-ATRP) technique on the roller-casted multiple thin PDMS layers. The characteristics of fabricated substrates were determined by static water contact angle measurement, X-ray photoelectron spectroscopy, and attenuated total reflection-Fourier transform infrared spectroscopy. In vitro cell behavior of POEGMA-grafted PDMS substrates was evaluated to examine cell-fouling resistance.
Asunto(s)
Incrustaciones Biológicas , Incrustaciones Biológicas/prevención & control , Adhesión Celular , Metacrilatos , Polimerizacion , Polímeros , Propiedades de SuperficieRESUMEN
The aim of this investigation was to enhance the biological behavior of NiTi shape memory alloy while preserving its super-elastic behavior in order to facilitate its compatibility for application in human body. The surfaces of NiTi samples were bombarded by three different nitrogen doses. Small-angle X-ray diffraction was employed for evaluating the generated phases on the bombarded surfaces. The electrochemical behaviors of the bare and surface-modified NiTi samples were studied in simulated body fluid (SBF) using electrochemical impedance and potentio-dynamic polarization tests. Ni ion release during a 2-month period of service in the SBF environment was evaluated using atomic absorption spectrometry. The cellular behavior of nitrogen-modified samples was studied using fibroblast cells. Furthermore, the effect of surface modification on super-elasticity was investigated by tensile test. The results showed the improvement of both corrosion and biological behaviors of the modified NiTi samples. However, no significant change in the super-elasticity was observed. Samples modified at 1.4E18 ion cm(-2) showed the highest corrosion resistance and the lowest Ni ion release.
Asunto(s)
Materiales Biocompatibles/síntesis química , Líquidos Corporales/química , Fibroblastos/citología , Fibroblastos/fisiología , Iones Pesados , Níquel/química , Nitrógeno , Titanio/química , Animales , Materiales Biocompatibles/efectos de la radiación , Línea Celular , Proliferación Celular/fisiología , Supervivencia Celular/fisiología , Ensayo de Materiales , Ratones , Níquel/efectos de la radiación , Propiedades de Superficie , Titanio/efectos de la radiaciónRESUMEN
The electrochemical and cellular behavior of commercially pure titanium (CP-Ti) with both ultrafine-grained (UFG) and coarse-grained (CG) microstructure was evaluated in this study. Equal channel angular pressing was used to produce the UFG structure titanium. Polarization and electrochemical impedance tests were carried out in a simulated body fluid (SBF) at 37°C. Cellular behaviors of samples were assessed using fibroblast cells. Results of the investigations illustrate the improvement of both corrosion and biological behavior of UFG CP-Ti in comparison with the CG counterpart.
Asunto(s)
Electroquímica , Titanio/química , Animales , Materiales Biocompatibles/química , Líquidos Corporales , Línea Celular , Proliferación Celular/efectos de los fármacos , Fibroblastos/efectos de los fármacos , Ensayo de Materiales , Ratones , Microscopía Electrónica de Transmisión , Tamaño de la Partícula , Propiedades de SuperficieRESUMEN
A combined freeze-drying and particulate leaching method for scaffold synthesis showed an improvement in the horizontal microstructure of the gelatin/chitosan scaffolds. Type and concentration of the cross-linking agent, freezing temperature, concentration of the polymeric solution and gelatin/chitosan weight ratio were the variables affecting the scaffold properties. Assessment of the tensile properties of the scaffolds revealed that for a scaffold with 50% chitosan, glutaraldehyde, as a cross-linking agent, created much tighter polymeric network compared to N,N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide (EDC). However, in the case of gelatin scaffolds, EDC was identified as the stronger cross-linker. Compressive behavior of the scaffolds satisfied formulations obtained from the theoretical modeling of the low-density, elastomeric foams. The investigation of the scaffold degradation indicated that the increase in the mechanical strength of the scaffolds would not always reduce their degradation rate.