Objective To investigate the effect of surface propertyof different polyether-ester block copolymers[poly(ethylene glycol-terephthalate)/poly(butylene terephthalate), PEGT/PBT] on the growth of smooth muscle cells (SMCs) and endothelial cells(ECs). Methods Three kinds of copolymers were synthesized, which were 1000-T20 (group A), 1000PEGT70/PBT30 (group B) and 600PEGT70/PBT30 (group C). The water-uptake and contact angle of three polyether-ester membranes were determined. The canine aorta smooth muscle cells and external jugular vein endothelial cells were primarily harvested, subcultured, and then identified. The proliferation of SMCs and ECs on the different polyether-ester membranes were investigated. Results The water-uptake of three copolymers arranged as the sequence of group C<group A<group B, and contact angle as the sequence of group C>group A>group B, indicating group B being more hydrophilic. However, smooth musclecells andendothelial cells grew poorly on the membrane of group B after low density seeding, but proliferated well on the membranes of group A and group C. Conclusion In contrast with more hydrophilic 1000PEGT70/PBT30, moderately hydrophilic 1000-T20 and 600PEGT70/PBT30 has better compatibility with vascular cells. The above results indicate that the vascular cells can grow well on moderately hydrophilic PEGT/PBT and that PEGT/PBT can be used in vascular tissue engineering.
Currently, as the key raw material of artificial biological heart valve, bovine pericardium is mainly depend on import and has become a “bottleneck” challenge, greatly limiting the development of domestic biological heart valve. Therefore, the localization of bovine pericardium is extremely urgent. In this study, the pericardium of Sichuan yak was compared with that of Australian cattle in terms of fundamental properties and anti-calcification performance. The results demonstrated that the appearance and thickness of yak pericardium were more advantageous than the Australian one. Sichuan yak pericardium and Australian cattle pericardium had comparable performance in shrinkage temperature, mechanical test and anti-calcification test. This study preliminarily verifies the feasibility of substitution of Australian cattle pericardium by Sichuan yak pericardium and promotes the progression of bovine pericardium localization with data support.
Objective To develop a biodegradable implantable bone material with compatible mechanics with the bone tissue, providing a new biomaterial for clinical bone repair and regeneration. Methods Silk reinforced polycaprolactone composites (SPC) containing 20%, 40%, and 60% silk were prepared by layer-by-layer assembly and hot-pressing technology. Macroscopic morphology was observed and microstructure were observed by scanning electron microscopy, compressive mechanical properties were detected by compression test, surface wettability was detected by surface contact angle test, degradation of materials was observed after soaking in PBS for 180 days, and proliferation of MC3T3-E1 cells was detected by cell counting kit 8 assay. Six Sprague Dawley rats were subcutaneously implanted with polycaprolactone (PCL) and 20%-SPC, respectively. Masson staining was used to analyze the in vivo degradation behavior and vascularization effect within 180 days. Results The pore defects of the three SPC sections were relatively few. In the range of 20% to 60%, as the silk content increased and the PCL content decreased, the interlayer spacing of silk fabric decreased, and the fibers almost covered the entire cross-section. The compressive modulus and compressive strength of SPC showed an increasing trend, and the compressive modulus of 60%-SPC was slightly lower than that of 40%-SPC. There were significant differences in compressive modulus and compressive strength between the materials (P<0.05). In vitro simulated fluid degradation experiments showed that the mass loss of the three types of SPC after 180 days of degradation was within 5%, with the highest mass loss observed in 60%-SPC. The differences in mass loss between the materials were significant (P<0.05). As the silk content increased, the static water contact angle of each material gradually decreased, and all could promote the proliferation of MC3T3-E1 cells. The subcutaneous degradation experiment in rats showed that 20%-SPC began to degrade at 30 days after implantation, and material degradation and vascularization were significant at 180 days, which was in sharp contrast to PCL. Conclusion SPC has the mechanical and hydrophilic properties that are compatible with bone tissue. It maintains its mechanical strength for a long time in a simulated body fluid environment in vitro, and achieves dynamic synchronization of material degradation, tissue regeneration, and vascularization through the body’s immune regulation mechanism in vivo. It is expected to provide a new type of implant material for clinical bone repair.
The poor mechanical property and vulnerability to bacterial infections are the main problems in clinic for dental restoration resins. Based on this problem, the purpose of this study is to synthesize silver-titanium dioxide (Ag-TiO2) nanoparticles with good photocatalytic properties, and add them to the composite resin to improve the mechanical properties and photocatalytic antibacterial capability of the resin. The microstructure and chemical composition of Ag-TiO2 nanoparticles and composite resins were characterized. The results indicated that Ag existed in both metallic and silver oxide state in the Ag-TiO2, and Ag-TiO2 nanoparticles were uniformly dispersed in the resins. The results of mechanical experiments suggested that the mechanical properties of the composite resin were significantly improved due to the incorporation of Ag-TiO2 nanoparticles. The antibacterial results indicated that the Ag-TiO2 nanoparticle-filled composite resins exhibited excellent antibacterial activities under 660 nm light irradiation for 10 min due to the photocatalysis, and the Ag-TiO2 nanoparticle-filled composite resins could also exhibit excellent antibacterial activities after contact with bacteria for 24 h without light irradiation because of the release of Ag ions. In summary, this study provides a new antibacterial idea for the field of dental composite resins.
The study of mechanical properties on heart valves can provide an important theoretical basis for doctors to repair heart valves and prosthetic valve materials research. In this paper, we present the current status of the mechanical property study methods of heart valve, expound the methods and special requirements about uniaxial tensile test and biaxial tensile test of the heart valve, and further discuss several establishment methods of heart valve constitutive models. We also discuss the development trend of heart valve mechanics.
ObjectiveTo improve the poor mechanical strength of porous ceramic scaffold, an integrated method based on three-dimensional (3-D) printing technique is developed to incorporate the controlled double-channel porous structure into the polylactic acid/β-tricalcium phosphate (PLA/β-TCP) reinforced composite scaffolds (double-channel composite scaffold) to improve their tissue regeneration capability and the mechanical properties. MethodsThe designed double-channel structure inside the ceramic scaffold consisted of both primary and secondary micropipes, which parallel but un-connected. The set of primary channels was used for cell ingrowth, while the set of secondary channels was used for the PLA perfusion. Integration technology of 3-D printing technique and gel-casting was firstly used to fabricate the double-channel ceramic scaffolds. PLA/β-TCP composite scaffolds were obtained by the polymer gravity perfusion process to pour PLA solution into the double-channel ceramic scaffolds through the secondary channel set. Microscope, porosity, and mechanical experiments for the standard samples were used to evaluate the composite properties. The ceramic scaffold with only the primary channel (single-channel scaffold) was also prepared as a control. ResultsMorphology observation results showed that there was no PLA inside the primary channels of the double-channel composite scaffolds but a dense interface layer between PLA and β-TCP obviously formed on the inner wall of the secondary channels by the PLA penetration during the perfusion process. Finite element simulation found that the compressive strength of the double-channel composite scaffold was less than that of the single-channel scaffold; however, mechanical tests found that the maximum compressive strength of the double-channel composite scaffold[(21.25±1.15) MPa] was higher than that of the single-channel scaffold[(9.76±0.64) MPa]. ConclusionThe double-channel composite scaffolds fabricated by 3-D printing technique have controlled complex micropipes and can significantly enhance mechanical properties, which is a promising strategy to solve the contradiction of strength and high-porosity of the ceramic scaffolds for the bone tissue engineering application.
In order to solve the problem of high cytotoxicity in vitro of nano-silver antibacterial gel, and the problem of large nano-silver particle size and size distribution, this study prepared nano-silver antibacterial gel with better biocompatibility and good antibacterial effect by using physical cross-linking method and using poloxamer as dispersant when prepared nano-silver. In this study, nano-silver was prepared by photo-initiator method and by adding poloxamer as a dispersant, and then UV-visible absorption spectrum test and scanning electron microscopy (SEM) test were carried out using prepared nano-silver mixture and particles after drying respectively. The gel was prepared through adjusting its pH value by using sodium bicarbonate, and then pH value test, SEM test for cross-section of gel, swelling ratio test, viscosity test, inhibition zone test and in vitro cytotoxicity test were carried out. The test results showed that the maximum absorption wavelength of prepared nano-silver, using poloxamer as dispersant and ultra-pure water as solvent, was 414 nm, and the average nano-silver size was about 60 nm. The prepared nano-silver using poloxamer as dispersant had smaller particle diameter and narrower particle size distribution than those using PVP as dispersant. Similarly, the prepared nano-silver using ultra-pure water as solvent also had smaller particle diameter and narrower particle size distribution than those using distilled water as solvent. The pH value of the prepared gel was between 5.8~6.1. The dried gel section had many holes. The water absorption of gel was fine and the viscosity of gel was fit to coat on the gauze. In addition, the prepared gel with nano-silver had greater ability to inhibit Escherichia coli and Staphyloccocus aureus at the concentrations of 24, 18 and 12 μg/mL. And the biocompatibility of the prepared gel with nano-silver was good when the concentration below 24 μg/mL. Based on the above features, the nano-silver antibacterial gel could be used in the treatment of burn or other wounds.
In order to establish a bone scaffold with good biological properties, two kinds of new gradient triply periodic minimal surfaces (TPMS) scaffolds, i.e., two-way linear gradient G scaffolds (L-G) and D, G fusion scaffold (N-G) were designed based on the gyroid (G) and diamond (D)-type TPMS in this study. The structural mechanical parameters of the two kinds of scaffolds were obtained through the compressive simulation. The flow property parameters were also obtained through the computational fluid dynamics (CFD) simulation in this study, and the permeability of the two kinds of scaffolds were calculated by Darcy's law. The tissue differentiation areas of the two kinds of scaffolds were calculated based on the tissue differentiation theory. The results show that L-G scaffold has a better mechanical property than the N-G scaffold. However, N-G scaffold is better than the L-G scaffold in biological properties such as permeability and cartilage differentiation areas. The modeling processes of L-G and N-G scaffolds provide a new insight for the design of bone scaffold. The simulation in this study can also give reference for the prediction of osseointegration after the implantation of scaffold in the human body.
Znic (Zn) alloys with good cytocompatibility and suitable degradation rate have been a kind of biodegradable metal with great potential for clinical applications. This paper summarizes the biological role of degradable Zn alloy as bone implant materials, discusses the mechanical properties of different Zn alloys and their advantages and disadvantages as bone implant materials, and analyzes the influence of different processing strategies (such as alloying and additive manufacturing) on the mechanical properties of Zn alloys. This paper provides systematic design approaches for biodegradable Zn alloys as bone implant materials in terms of the material selection, product processing, structural topology optimization, and assesses their application prospects with a view to better serve the clinic.
Objective To summarize the influence of microstructure on performance of triply-periodic minimal surface (TPMS) bone scaffolds. Methods The relevant literature on the microstructure of TPMS bone scaffolds both domestically and internationally in recent years was widely reviewed, and the research progress in the imfluence of microstructure on the performance of bone scaffolds was summarized. Results The microstructure characteristics of TPMS bone scaffolds, such as pore shape, porosity, pore size, curvature, specific surface area, and tortuosity, exert a profound influence on bone scaffold performance. By finely adjusting the above parameters, it becomes feasible to substantially optimize the structural mechanical characteristics of the scaffold, thereby effectively preempting the occurrence of stress shielding phenomena. Concurrently, the manipulation of these parameters can also optimize the scaffold’s biological performance, facilitating cell adhesion, proliferation, and growth, while facilitating the ingrowth and permeation of bone tissue. Ultimately, the ideal bone fusion results will obtain. Conclusion The microstructure significantly and substantially influences the performance of TPMS bone scaffolds. By deeply exploring the characteristics of these microstructure effects on the performance of bone scaffolds, the design of bone scaffolds can be further optimized to better match specific implantation regions.