Papers by Keyword: Collagen

Abstract: The biphasic calcium phosphate (BCP) concept was introduced to overcome disadvantages of single phase biomaterials. In this study, we prepared BCP from nanoHA and β-TCP that were synthesized via a solid state reaction. Three different ratios of pure BCP and collagen-based BCP scaffolds (%HA/%β-TCP; 30/70, 40/60 and 50/50) were produced using a polymeric sponge method. Physical and mechanical properties of all materials and scaffolds were investigated. XRD pattern proved the purity of each HA, β-TCP and BCP. SEM showed overall distribution of macropores (80-200 µm) with appropriate interconnected porosities. Total porosity of pure BCP (93% ± 2) was found to be higher than collagen-based BCP (85%± 3). It was observed that dimensional shrinkage of larger scaffold (39% ± 4) is lower than smaller one (42% ± 5) and scaffolds with higher HA (50%) ratio experienced greater shrinkage than those with higher β-TCP (70%) ratio (45% ±3 and 36% ±1 respectively). Mechanical properties of both groups tend to be very low and collagen coating had no influence on mechanical behavior. Further studies may improve the physical properties of these composite BCP.

Abstract: nanohydroxyapatite (nHA) and collagen were utilized to fabricate the bio-inspired organic-inorganic composite coating (OICC) via the Drop-on-Demand (DoD) micro-dispensing technique, which could flexibly construct multi-layer structures with varied materials composition within a layer and /or among layers reliably. This technique has been further investigated on its capability of OICC fabrication with regards to various materials (hydroxyapatite and collagen) as well as its dispensing parameters. A four-layered structure was formed, with the sequence of nHA-collagen-nHA-collagen from bottom to top. The dispensing parameters were also investigated with regards to the characteristics of the OICC fabrication. The coating was then subjected to various characterizations including scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and adhesion test. SEM and XRD results revealed that the DoD micro-dispensing technique did not change the morphology and phase of these two coating materials. And the results of EDS further demonstrated the corresponding elemental distributions within the four-layered coating structure which demonstrated the feasibility of the DoD micro-dispensing technique for the fabrication of thin-layered OICC.

Abstract: Extensive interest in bone tissue engineering focuses on bio-degradable materials based on natural polymers. One of these polymers is chitosan which is deacetylated derivative of chitin. The paper presents preparation of chitosan scaffolds containing collagen and hydroxyapatite by electrolytic method. Chitosan dissolved in acetic acid forms chitosan acetate which is polyelectrolyte (protonated group NH3⁺). The flow of current through a solution of chitosan acetate causes its reduction and accumulation of chitosan on cathode. Formed structure is highly hydrated porous hydrogel. Hydrogel structure can be coated (in the process of electrodeposition) by nano-silver having a bactericidal effect. Subsequently hydrogel was frozen at -37°C for 24h and freeze-drying. Obtained scaffold has a high porosity (more than 88%) with average pore size of about 0.1-3 μm (micropores) and 0,1- few millimeters (macropores).

Abstract: Glyoxylic acid was used to carboxylic collagen protein which obtained by the hydrolysis of gelatin. Al (Ⅲ) was complex to it with aluminium tanning principle in tanning chemistry and the novel flocculent (CGAl) was prepared. Use CODcr removal rate, suspended solid and chroma to indicate the flocculation effect on waste drilling water. The results indicated that when CGAl was used, its dosage was 10.5g/L and the range of pH and temperature were widely. After flocculation, CODcr removal rate was 92.3%, suspended solid decreased from 2115mg/L to 65mg/L, and chroma reduced from 1003 times to 6 times. So the flocculation effect was obviously.

Abstract: Collagen-based materials were prepared and their properties were studied. The shape of collagen materials was as follows: thin films, hydrogels, and sponges. Microstructure and mechanical properties of films and sponges were studied. The effect of cross-linking agents and the effect of synthetic polymer on the properties of collagen materials were studied and analyzed. Collagen-based materials can be considered as potential biomaterials in tissue engineering.

Abstract: Small caliber vascular replacement (<4 mm) still remains a challenge for medical and research teams, as no available vascular substitutes (VS) are suitable for small diameter bypass. Vascular engineering proposes new models of small diameter VS but rare are those that meet the biocompatibility and mechanical criteria. In this study, we developed a new scaffold made by the combination of two natural biomacromolecules: collagen and silk fibroin. The scaffold was further cellularised with porcine smooth muscle cells. First, the behavior of cells in the collagen-fibroin constructs was verified in order to evaluate the biocompatibility of the scaffold with the cells. Then, gel mass loss and cellular attachment, morphology, spreading and viability were analysed. The results showed an excellent interaction and biocompatibility between collagen, silk fibroin fibers and cells. Thus, the collagen-fibroin construct appears to be a very attractive material for vascular tissue engineering.

Abstract: Collagen/cellulose films were made by the blend solutions of collagen, cellulose in this paper. To begin with, collagen and cellulose was dissolved in 1-allyl-3-methylimidazolium chloride ([Amim]Cl）. The structure of the blend films was characterized by FTIR and XRD. The effects of weight ratio between the two polymers on light transmittance, tensile strength, elongation at break and water absorption of the film were studied. The results showed that there were strong interactions and good compatibility between collagen and cellulose in the film and the polymers have strongest interactions at the mixing ratio of 5:5. The blend films possess better properties such as mechanical and water absorption properties than those made of single polymer.

Abstract: In the present study, the goatskin collagen matrices were tanned by chrome powder and chestnut extract. The samples were then thermocycled in a container at different temperature ranges with a dwell time of 5 h for different cycles. The thermal degradation behaviors of the collagen matrices before and after the thermocycling were investigated. The Coates-Redfern Method was applied to study the thermal degradation kinetics of different samples. The results indicate that the thermocycling exerted more dramatic effect on the native collagen matrices than on tanned samples. The tanning process endows the samples with extra crosslinking structure, and therefore, less sensitivity to thermocycling treatment. It was found that the thermal treatment at moderate temperature (0~50˚̓˹˰̵̵̵̴͈͂̈́˰̵̼̹̼̈́̈́˰̶̵̵̹̼̳̾̾ͅ˰̿̾˰̸̵̈́˰̸̵̱̼̈́͂̽˰̴̵̷̴̱̱̹͂̈́̿̾˰̱̳̹̱̹̈́͆̈́̿̾˰̵̵̷̵̹̾͂̓˰˸ΔE) of the sample. However, for the samples thermocycled at high upper limit temperature (0~150˚̓˹˼˰ΔE was decreased significantly.