| Objective:To construct a sort of silica nano-assembly modified with ultra-small cerium oxide nanoparticles?CeNP@Si O2?,explore thier antioxidative properties,drug-release properties,biocompatibilities and application in in acute skin wound healing,reveal the internal mechanism of wound skin healing,and try to provide a way to develop a new type of nano-preparation for promoting skin wound healingMethods:Cerium oxide nanoparticles?CeNP?with ultra-small size were synthesized by chemical thermal decomposition method,and followed by surface brominated modification.The size,morphology,composition,crystal form and structure of CeNP were characterized by scanning electron microscope?SEM?,high resolution transmission electron microscope?HRTEM?,selective area electron diffraction?SAED?,X-ray powder diffraction?XRD?and elemental analyzer.Using cetyltrimethyl ammonium chloride?CTAC?and water as template and solvent individually,silica?SiO2?nanospheres were synthesized by the sol-gel method,and their surface was also modified with amino groups.The size,morphology,composition,and structure of the SiO2 were also characterized by SEM and TEM.The specific surface area and pore size were detected by a fully automatic specific surface analyzer,and its release properties were measured by an ultraviolet visible spectrophotometer.The CeNP@SiO2 nano-assembly was obtained by nucleophilic substitution reaction between the modified CeNP nanoparticles and Si O2 nanospheres.The effects of reactant dosage on the morphologies of products were explored.The size,morphology,structure,and composition of the CeNP@SiO2 nano-assembly were also characterized by SEM,TEM,and Mapping elemental analyzer.Using ferulic acid?FA?as a drug model,the drug-release properties of the Si O2nanospheres and CeNP@SiO2 nano-assembly were studied individually.Some propeties of the CeNP@SiO2 nano-assembly were studied with in vitro cell experiments,such as the interaction between the CeNP@SiO2 nano-assembly and cytoskeletal actin?or cells?,cell uptake performance,antimicrobial activities,oxidative stress induced by hydrogen peroxide,and so on.An acute-skin-trauma animal model was established,by which the healing effect of the acute skin wounds intervened by the CeNP@SiO2 nano-assembly were evaluated.Moreover,histochemical staining was used to evaluate the wound tissue.Results:1.The polycrystalline cerium oxide nanoparticles with a diameter of?3 nm were successfully synthesized,which present regular morphology,uniform size and even distribution.At the same time,the porous Si O2 nanospheres with a diameter of?30 nm,uniform size and good dispersion were also obtained.The specific surface area and pore size of the SiO2 nanospheres is about 280 m2·g-11 and 3.5 nm individually.After mixing the CeNP and SiO2 nano-dispersion?v/v=3:1?with same concentration,there were many adhesive products with unobvious morphological and poor dispersion.However,when their volume ratio was changed into 5:1,the typical morphological products with good dispersion were obtained.The cumulative release rates of pure FA and FA-Si O2 nanospheres reached the maximum value at 4 h?93%and 62%,respectively?,but that of the FA-CeNP@SiO2 nano-assembly was only 20%at same time,and then increased slightly to 30%at 72 h.2.After treated by the CeNP@SiO2 nano-assembly,there were no significant abnormal changes for focal adhesion protein and cell skeletal actin on the surface of cells.When cells were coincubated with the RITC-SiO2 and RITC-CeNP@SiO2 for 4 h,there were more RITC-labeled nanomaterials in the cytoplasm.When E.coli treated with the SiO2nanospheres and CeNP@SiO2 nano-assembly,the OD value of the blank control group,CeNP@SiO2 nano-assembly group,and SiO2 nanosphere group,were 4.30,1.80 and 0.75individually.The OD value of the blank control group was about 6 times higher than that of the SiO2 nanosphere group,and 2.5 times higher than that of the CeNP@SiO2 nano-assembly group.However,the difference of OD value of Pseudomonas aeruginosa group treated with SiO2 nanospheres and CeNP@SiO2 nanomaterials were small.3.Compared with the blank control group?without H2O2 stimulation?and the H2O2-stimulated positive control,the DCF fluorescence of cells treated with the H2O2-stimulated SiO2 nanospheres increased significantly.However,for the H2O2-stimulated CeNP@SiO2nano-assembly group,there was no significant difference in the intensity of DCF fluorescence of cells.Using the skin-wound-surface SD rats as model,the skin wound surface treated with the blank control group,Si O2 nanosphere experimental group and CeNP@SiO2 nano-assembly experimental group,decreased respectively from 2 cm to 4 mm,8 mm,and 8 mm after 10 days.There was less collagen deposition in the wound tissue for the blank control group and SiO2 nanosphere group when the wound areas stained by Picric acid scarlet,while that of the Ce NP@SiO2 nano-assembly treatment group increased significantly.After the wound tissue treated by the CeNP@SiO2 nano-assembly were stained by Masson's three-color,there were more expression of?-smooth muscle actin and formation of skin appendages similar structures in granulation tissue of trauma area with the increase of treatment days.Conclusion:1.The CeNP@SiO2 nano-assembly with good drug-release properties was successfully prepared by two step route.2.The as-prepared Ce NP@SiO2 nano-assembly has good biocompatibility and antibacterial activity,and it has obvious inhibit role the proliferation of E.coli.3.The CeNP@SiO2 nano-assembly can improve wound healing for SD rats by removing intracellular ROS levels.In the same time,it can effectively promote collagen deposition in wound area and expression of?-smooth muscle actin,which result in the high quality of wound healing. |
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