ABSTRACT
Objective: To prepare nerve growth factor(NGF) temperature sensitive in situ gel and investigate its therapeutic effect on sciatic nerve injury of rats.Method: NGF thermosensitive gel was prepared and its prescription was optimized by central composite design-response surface methodology.Fifty rats were randomly divided into the normal group,model group,NGF injection group(10 mg·L-1),NGF low-dose(10 mg·L-1) and high-dose(20 mg·L-1) thermosensitive gel groups,and sciatic nerve injury model of rats was established.The effect of NGF thermosensitive gel on the injury of sciatic nerve were comprehensively examined by taking rat behavior,sciatic nerve function index(SFI),time of withdrawal reflex,wet weight ratio of gastrocnemius muscle,and histomorphological changes as indicators.Result: The gelation temperature of NGF thermosensitive gel was 35.2℃ after the formulation being optimized,which was in line with the standard for injection.Four-eight weeks after operation,the SFI and wet weight ratio of gastrocnemius muscle in rats of NGF high-dose thermosensitive gel group were significantly higher than those in the model group and NGF injection group,but its time of withdrawal reflex was significantly lower than those in the model group and NGF injection group,and the effect was in a dose-dependent manner.Arrangement of regenerated nerve fibers in sciatic nerve injury area of rats from NGF high-dose thermosensitive gel group was more tidy,dense and continuous than that of the model group.Conclusion: NGF thermosensitive gel can promote repair of sciatic nerve injury in rats.
ABSTRACT
OBJECTIVE: To synthesis chitosan/β-glycerophosphate (CS/β-GP) thermosensitive hydrogel containing multi-walled carbon nanotubes-polyethyleneimine (MWCNTs-PEI) complexes and to lay a foundation for further research of dual slow-release delivery system. METHODS: Chitosan thermosensitive hydrogel containing MWCNTs-PEI was prepared by MWCNTs-PEI dispersed to the chitosan thermosensitive hydrogel. As the indicator of the gelling time, the experiment studied the effect of β-GP concentration, pH, temperature and MWCNTs-PEI composite quality on the thermosensitive chitosan hydrogel, and then it was charactered by using transmission electron microscopy (SEM), infrared spectrometer(IR), and initially investigated in vivo compatibility. RESULTS: The dynamic rheology method investigated the gelling temperature were about 37.0°C. Within a certain range, the gelling time of thermosensitive chitosan hydrogel was shortened with the increase of concentration of β-GP, pH, temperature, and the quality of MWCNTs-PEI complexes, and they could be transformed into the hydrogel in vivo. The addition of MWCNTs-PEI complex didn't react chemically with the thermosensitive chitosan hydrogel and significantly make the holes of the chitosan thermosensitive hydrogel smaller by SEM and FT-IR, eventually leading to the swelling rate and the corrosional ratio decrease. CONCLUSION: Chitosan/β-glycerophosphate thermosensitive hydrogel containing amino-carbon nanotubes has a rapid gelation and good temperature-sensitivity, which can serve as a good double sustained-release carrier.
ABSTRACT
OBJECTIVE: To synthesize water-soluble multi-walled carbon nanotubes-polyethyleneimine (MWCNTs-PEI) composite with low cytotoxicity and to lay a foundation for further research of loading drugs with carbon nanotubes. METHODS: MWCNTs-PEI composite was prepared by modifying carboxylated multi-walled carbon nanotubes(MWCNTs-COOH) with polyethylene (PEI), and then the composite was characterized by transmission electron microscopy, infrared spectra, UV spectra and thermalgravimetric analysis. The cytotoxicity of the composite on PC12 cells was measured by methyl thiazolyl tetrazolium(MTT) assay to preliminarily evaluate its biocompatibility. RESULTS: The dissolubilities of MWCNTs-PEI and MWCNTs-COOH complexes were respectively 1.009 and 0.0601 mg · mL-1, and the former was about 16 times of the latter. The cytotoxicity of MWCNTs-PEI composite on PC 12 cells was significantly milder than that of MWCNTs-COOH composite as indicated by MTT assay (P < 0.05). CONCLUSION: MWCNTs-PEI composite not only improves the dispersibility of carbon nanotubes, but also reduces its in vitro cell toxicity.