Papers by Author: Fu Zhai Cui

Abstract: In the present study, a new antibacterial bone graft substitute has been developed for repairing bone defects and inhibiting related infections at the same time. Calcium sulphate hemihydrate (CSH) was introduced into nanohydroxyapatite/collagen (nHAC) to prepare a self-setting in situ bone repair materials. The nHAC/CSH was used as a carrier of vancomycin (VCM) for anti-infection and the treatment of osteomyelitis. The VCM/nHAC/CSH composite was a porous scaffold with porosity of 38.8% and the compressive mechanical strength was about 4.8 MPa. The final setting time was about 15~20 min. The inhibition ratio of VCM/nHAC/CSH was more than 99.8% and the distinct inhibition zone of 18 mm was formed in Staphylococcus aureus bacterium incubation dish with VCM/nHAC/CSH disc in the center of agar matrix for 16 hours of incubation. After incubating 17 days at 37 in vitro, the concentration of vancomycin in elution fluild was around 12 μg/mL. Therefore, the VCM/nHAC/CSH bone substitute presents ideal self-setting antibacterial, cytocompatibility, sustained release properties and has great potential applications for the treatment of bone defect-related infection in orthopedic surgeries.

Abstract: To explore a new type of injectable composite cements similar to the natural bone in both composition and hierarchical structure, the mineralized collagen and calcium sulphate dihydrate（CSD）were incorporated into α-calcium sulphate hemihydrate (α-CSH).The mineralized collagen was synthesized biomimetically by nanohydroxyapatite/collagen. We investigated the injectability, the setting time and the biomechanics properties to find an ideal combination of them to prepare the composite cements. SEM analysis showed biphasic cements consisting of an entanglement of calcium sulfate dihydrate and calcium-deficient hydroxyapatite crystals. We prepared porcine thoracolumbar burst fracture models and made the vertebroplasty for them by the composite cements. Imaging analysis showed the composite cements distributed uniformly and solidified well. Biomechanical test showed the ability of composite cements to repair spinal burst fractures was significant.

Abstract: In this paper, the combined artificial bone made from α- calcium sulphate hemihydrate（α-CSH） and β- tricalcium phosphate (β-TCP) was investigated and at the same time the study explored: the method of preparing the combined artificial bone. Scanning electron microscopy (SEM), Powder X-ray diffraction (XRD), Thermogravimetric (TG), Differential scanning calorimetry (DSC), and Mercury porosimeter were employed to characterize the samples. Results indicate that the combined artificial bone can be prepared by α-CSH and β-TCP using dehydrated alcohol as a solvent; β-TCP was made from cancellous bone in the femur of cattle under special conditions, which contained the spatial structure of normal cancellous bone; α-CSH was made from CSD under special temperature and pressure, which is more pure and regulation in crystal form.

Abstract: Nano-hydroxyapatite/collagen composite was processed at room temperature, 180°C, 200°C and 220°C under atmosphere for 10 min respectively. The morphology of the samples was characterized by scanning electron microscopy (SEM). The structure and components of the samples were investigated by energy dispersive spectrograph (EDS), X-ray powder diffractometer (XRD) and Fourier transform infrared (FTIR). The results of SEM and EDS for nHAC changed greatly at 200°C and 220°C in comparison with room temperature. The morphology and structure of nHAC at 180°C were similar to those at room temperature. It was demonstrated that nHAC possessed thermal stability in morphology and structure.

Abstract: This paper reported a newly designed retrievable urethral stent used in treatment of urethral strictures. The spiral urethral stent is made of Poly (l-lactide) (PLLA), adding barium sulphate (BaSO4) to certain content, which can be displayed precisely under X-ray after implanted in body. The stent was clinically tested in 32 patients with recurrent urethral strictures and was left in the urethra for 5 to 12 months. The response to the effect of the stent was assessed using symptom scores, peak flow rate (Qmax), residual urine volume (RUV), stent degradation, infection and outcome. During the treatment, there were not any inflammations found. The mechanical properties of the stent are almost the same as those of the PLLA stent without BaSO4. Improvements in patient symptom score, mean Qmax and RUV were significant at the 18 month follow-up. The infection was not observed. The stent was taken out easily through urethral forceps. In no patient was the stent obstructed by incrustation for up to 1.5 years.

Abstract: In this paper, an overview on nanoindentation and its combination with AFM is presented with regard to current instrument technology and applications on dental and bony tissues. Nanoindentation has been a widely used technique to determine the mechanical properties such as nanohardness and Young’s modulus for nanostructured materials. Especially, atomic force microscopy (AFM) combined with nanoindentation, with the pit positions controlled accurately, become a powerful technique used to measure mechanical properties of materials on the nanoscale, and has been applied to the study of biological hard tissues, such as bone and tooth. Examples will be shown that significantly different nanohardness and modulus in the isolated domains within single enamel, the prisms, interprisms, the surrounding sheaths and the different parts of skeletal bone, could been distinguished, while such information was unable to be obtained by traditional methods of mechanical measurements.

Abstract: A part of the titanium dental implant surface, which will meet connective tissue after being inserted in mandibular bone, was coated with calcium phosphate by ion beam assisted deposition (IBAD). Twenty-four implants of coated and uncoated group were randomly placed in mandibles after 3 months of premolars extraction in beagle dogs. All the implants were firmly anchored in the bone and had no clinical signs of peri-implant inflammation after 3-month insertion. The probing depth in calcium phosphate coated group is 1.9±0.2 mm, less than in control group (2.1±0.2 mm) (p<0.05). Most of the probing sites tended to bleed upon probing in two groups. It might indicate that the calcium phosphate coating has the potential to promote soft tissue integration.

Abstract: Implantable neural prostheses form hybrid interfaces with biological constructs, and the application of electrical fields can restore functions of patients with neurological damages. The various stoichiometric compositions of iridium oxide were synthesized using reactive magnetron sputtering. The charge injection behavior of iridium oxide deposited with an O2/Ar ratio of 0.5 was similar to pure Ir. The charge density of iridium oxide increased with increasing O2/Ar ratio, and increasing thickness of iridium oxide.

Abstract: Nanocomposites of hydroxyapatite-fibroin (HA-FB) were prepared using the biomimetic process. The Nanocomposites were detected with X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The FTIR results showed that chemical bond forms between HA nanocrystals and fibroin protein. The secondary structure of fibroin can be affected by the mineralization process. TGA results indicated the content of mineralized fibroin in the nanocomposites can be freely adjusted by changing the initial concentration of fibroin solution. TEM image showed that the diameter of the single mineralized nanofibrils is about 2-3 nm and the nanofibrils can aggregate into bundles with the size of 6-8 nm in width and 30-60 nm in length.

Abstract: To evaluate the biocompatibility of biomedical materials for hepatic tissue engineering, another new method was introduced to observe hepatocytes functions. In this experiment, hepatocytes were seeded onto four kinds of membranes of PLLA, PLGA (90:10), PLGA (75:25), and Chitosan cross-linked with collagen. The culture mediums were collected at 21 day after seeding, and then albumin (Alb), Urea (UN), glucose (Glu), total protein (TP), and triglyceride (TG) in the supernatant were detected by automatic biochemical analyzer. Results showed that hepatocytes on film of Chitosan cross-linked with collagen exhibited the highest level of TP and TG. These results were highly corresponding with the results of morphological observation. This data indicated that analyzing TP and TG in culture medium by automatic biochemical analyzer might be applied to evaluate hepatocytes biocompatibility on materials as a convenient and feasible method.