Objective To fabricate a nanohydroxyapatite-chitosan(nano-HA-CS) scaffold with high porosity by a simple and effective technique and to evaluate the physical and chemical properties and the cytocompatibility of the composite scaffold. Methods The threedimensional nano-HA-CS scaffolds with high porosity were prepared by the in situ hybridization-freeze-drying method. The microscopic morphology and components of the composite scaffolds were analyzed by the scanning electron microscopy (SEM), the transmission electron microscopy（TEM）, the X-ray diffraction（XRD）examination, and the Fourier transformed infrared spectroscopy（FTIR）. The calvarial osteoblasts were isolated from the neonatal Wistar rats. The serial subcultured cells (3rd passage) were respectively seeded onto the nanoHACS scaffold and the CS scaffold, and then were cocultured for 2, 4, 6 and 8 hours. At each time point,four specimens from each matrix were taken to determine the celladhesion rate. The cell morphology was observed by the histological staining and SEM. Results The macroporous nanoHACS scaffolds had a feature of high porosity with a pore diameter from 100 to 500 μm (mostly 400500 μm). The scaffolds had a high interval porosity; however, the interval porosity was obviously decreased and the scaffold density was increased with an increase in the contents of CS and HA. The SEM and TEM results showed that the nanosized HA was synthesized and was distributed on the pore walls homogeneously and continuously. The XRD and FTIR results showed that the HA crystals were carbonatesubstituded and not wellcrystallized. The cytocompatibility test showed that the seeded osteoblasts could adhere the scaffolds, proliferating and producing the extracellular matrix on the scaffolds. The adherence rate for the nanoHACS scaffolds was obviously higher than that for the pure CS scaffolds. Conclusion The nano-HA-CS scaffolds fabricated by the in situ hybridization-freeze-drying method have a good physical and chemical properties and a good cytocompatibility; therefore, this kind of scaffolds may be successfully used in the bone tissue engineering.
Objective To develop the plastic nano-hydroxyapatite (nano-HA)/poly (3-hydroxybutyrate-hydroxyvalerate) polyethylene glycol(PHBV-PEG) gentamicin (GM) drug delivery system(DDS)(nano-HA/PHBV-PEG-GM-DDS) for treating osteomyelitis and find its releasing character in vivo. Methods The plastic nano-HA/PHBV- PEG-GM-DDS was prepared using nanoHAas the core carrier of GM, nano-HA with PHBV and PEG as coating and plastic fibrin glue(FG) as microsphere scaffold. The morphological features of nano-HA,drug loaded nano-HA and drug loaded nano-HA/PHBVPEG microsphere were examined by electron microscope.The GM concentration in blood, cortex bone and cancellousbone was detected at 12 different time points by the method of K-B after the plastic nano-HA/PHBV-PEGGM-DDS was implanted into the femora of 36 rabbits. Its GM releasing character was assayed in vivo. Results Nano-HA was similar to a blackjack, and its length was less than 60 nm. Drug loaded nano-HA appeared natural crystal condensate, of which surface adsorbed massive GM. The average grain diameter was 200.5 nm. Drug loaded nanoHA/PHBV-PEG microsphere had a shrinkable porous structure, of which surface configuration was consistent. The average grain diameter was 34.5 μm. The GM concentration and the antibacterial annulus was in the linear correlation. The correlation coefficient was 0.998. In cortex and cancellous bone tissue, the GM concentration was about 95.50±16.50 μg/ml and 80.20±13.80 μg/ml from the plastic nano-HA/PHBV-PEG-GM-DDS on the 1st day, then decreased gradually. After 56 days of operation, the GM concentration still exceeded the minimum inhibitory concentrationfor the staphylococcus aureus, but the peak level of serum GM concentration wasunder the nephrotoxicity concentration. Conclusion Plastic nano-HA/PHBV-PEG-GM-DDS was a good drug delivery system with sustained antibiotic effect in vivo. It was an effective method for the treatment of osteomyelitis.