Biomedical subjects

Fu-zhai Cui

Publications and source records attributed to Fu-zhai Cui.

6 recordsLinked to original sources

PubMed2004

Effect of nano-hydroxyapatite/collagen composite and bone morphogenetic protein-2 on lumbar intertransverse fusion in rabbits.

OBJECTIVE: To investigate the effect of nano-hydroxyapatite/collagen (nHA/collagen) composite as a graft extender and enhancer when combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) on lumbar intertransverse fusion in rabbits. METHODS: Sixty-four adult female New Zealand white rabbits, aged 1 year and weighing 3.5-4.5 kg, underwent similar posterolateral intertransverse process arthrodesis and were randomly divided into 4 groups based on different grafts: autogenous cancellous bone alone (ACB group), nHA/collagen alone (HAC group), half autogenous cancellous bone and half nHA/collagen (ACB+HAC group) and nHA/collagen combined with rhBMP-2 (HAC+BMP group). The fusion masses were analyzed by manual palpation, radiography, biomechanical testing and histological examination. RESULTS: Fusion was observed in 4 cases in the 6th week and in 5 cases in the 10th week after surgery in ACB group. No case showed fusion in HAC group. In ACB+HAC group, there was fusion in 3 cases in the 6th week and in 4 cases in the 10th week after surgery. In HAC+BMP group, fusion in 1 case was found in the 4th week, in 5 cases in the 6th week and in 6 cases in the 10th week after surgery. It suggested that ACB, ACB+HAC and HAC+BMP groups showed similar fusion ratio and mechanical strength in the 6th and 10th week after surgery. According to the microstructure analysis of the samples, nHA/collagen had no negative effect when implanted together with ilium autograft. In HAC+BMP group, new bone-like tissue was observed in the 2nd week postoperatively, and nearly all of the implanted composites were replaced by mature bone matrix and new bones in 10th week postoperatively. CONCLUSIONS: The nHA/collagen, especially combined with rhBMP-2, is a promising bone substitute, for it has quick biodegradation, fine bone-bending ability, and high osteoconductivity on posterolateral spinal fusion in rabbits.

Analysis of Variance↗

PubMed2004

[Microcosmic analysis of TCP/HA coating with micro-pores on titanium by IBAD method.].

PURPOSE: In order to improve the biocompatibility of dental implants, the physical structure and the chemical composites of tricalcium phosphate/hydroxyapatite(TCP/HA) coating on titanium were studied. METHODS: Coatings of TCP/HA and hydroxyapatite (HA) on titanium were formed by ion beam assisted deposition (IBAD) method. The scanning electron microscope (SEM) and atomic force microscope (AFM) were used to study the morphology of the coating surfaces. The chemical components and structure of the modified surfaces were characterized using energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). RESULTS: The results showed that there were many micro-pores in the TCP/HA coating by SEM and AFM. The chemical components analysis showed that the Ca/P ratio of TCP/HA coating was lower than that of HA coating. The XRD showed that the TCP/HA coating was composed of TCP and HA. CONCLUSION: The results indicated that the TCP/HA coating with micro-pores was formed on titanium by IBAD method successfully. With higher binding strength between TCP/HA and titanium, this coating will be a potential coating material for dental implant, especially for the biological seal at the cervical level of the implant.

Calcium Phosphates↗

PubMed2004

[Kinetic study on collagen mineralization by ultraviolet absorption spectra].

The mechanism of collagen mineralization was studied by ultraviolet photometry method. The reaction solution was determined using ultraviolet-visible spectrophotometer by the method of repeat scanning wavelength. The recorded curves provided the spectroscopic and kinetics information of the reaction solution. It was found that the wave trough appeared on the step-like kinetic curve of mineralization of collagen. With the increase in initial concentration of calcium phosphate, the wave trough intensity increased and its position moved forward. The curves of scanning wavelength at different time showed different patterns. By analyzing the change in scanning wavelength curves, and the X-ray diffraction spectra of specimens before and after the wave trough position (the specimens were obtained by quickly freezing the solution and freeze-drying), it was suggested that gelation and phase separation occurred during the process of collagen mineralization. Collagen molecules loading calcium were cross-linked by newly formed DCPD in a "point to point" mode. The phase separation occurred in the fluid-filled space and the wave trough occurred in the ultraviolet absorption spectrum. Based on the mechanism the varieties of phenomena in the ultraviolet absorption spectrum during collagen mineralization were explained.

Absorption↗

PubMed2004

[Study of the nucleation sites in collagen mineralization].

By comparing IR spectra of collagen, collagen/CaCl2 and collagen/calcium phosphate, it was found that intensities of amide I, II and III bands were significantly decreased after mineralization. Band amide I shifted to wards lower wave number. This shift indicated chemical interaction between carboxyl groups and Ca ions formed in the mineralization. The result indicated that there was another nucleation site, i.e. carbonyl [structure: see text] on collagen, besides the previous reported nucleation site of carboxyl (-COOH) on collagen. The decrease of amide I peak intensity was mainly due to blockage of C=O stretch. Comparing the IR spectra of demineralized collagen and pure collagen, amide I, II and III peaks intensity and position were almost the same. When the mineral dissolved, amide peaks rebounded, which indicated that the crystals nucleated on these sites enwrapped the groups and blocked the groups vibration. The decreases of peak intensity of amide I, II and III were different due to their different vibration modes. The result confirmed that the carbonyl group was one kind of the nucleation site during collagen mineralization. The relationship between the process of collagen mineralization and variety of amide bonds was also studied.

Amides↗

PubMed2003

[Mineralized collagen based composite for bone tissue engineering].

OBJECTIVE: To construct a mineralized collagen based composite by biomimetic synthesis for bone tissue engineering. METHODS: Using the molecular collagen as the template, the calcium phosphate is deposited on it to produce a mineralized collagen based composite, then is combined with minute amount of poly lactic acid (PLA), the three-dimensional scaffold composite is prepared by liquid phase separation. Using osteoblast culture technique, the biocompatibility of this biomaterial in vitro is detected by x-ray diffraction, SEM, TEM, fluoroscopy and CLSM. RESULTS: Both degree and the size of crystals in the composite are low, which are similar to that of nature bone. It possesses porous structure and the porosity of the composite is high. The typical fibrillar microstructure is self-assembled of the collagen and the nano-crystal hydroxyapatite (HA) in the composite, moreover, the x-ray diffraction graphic of HA crystal shows the [002]-oriented. CONCLUSIONS: The biomimetic three-dimensional composite can serve as one of the optimal scaffold material for bone tissue engineering both on structure and on property.

Animals↗

PubMed2002

[Nano-hydroxyapatite/collagen composite for bone repair].

OBJECTIVE: To develop nano-hydroxyapatite/collagen (NHAC) composite and test its ability in bone repairing. METHODS: NHAC composite was developed by biomimetic method. RESULTS: The composite showed some features of natural bone in both composition and microstructure. The minerals could contribute to 50% by weight of the composites in sheet form. The inorganic phase in the composite was carbonate-substituted hydroxyapatite (HA) with low crystallinity and nanometer size. HA precipitates were uniformly distributed on the type I collagen matrix without preferential orientation. The composite exhibited an isotropic mechanical behavior. However, the resistance of the composite to localized pressure could reach the lower limit of that of femur compacta. The tissue response to the NHAC composite implanted in marrow cavity was investigated. Knoop micro-hardness test was performed to compare the mechanical behavior of the composite and bone. At the interface of the implant and marrow tissue, solution-mediated dissolution and macrophage-mediated resorption led to the degradation of the composite, followed by interfacial bone formation by osteoblasts. The process of implant degradation and bone substitution was reminiscent of bone remodeling. CONCLUSION: The composite can be incorporated into bone metabolism instead of being a permanent implant.

Animals↗