The Impact Of Pore Structure On The Drug Releasing Process Of β-tricalcium Phosphate Artificial Vertebral Body

Objective: Based on the the previous study on the β-tricalcium phosphate(β-TCP)artificial vertebral body with bone repair and anti-infectious effect,the effects of controlled layer with different pore structure were investigated on the structure,property and drug releasing process of β-TCP artificial vertebral body.Methods: The controlled β-TCP layer with different pore structure were produced by different sintering temperatures,pore forming agents with different diameters and doges.The controlled layers were divided into three groups: sintering temperature group(900℃,1000℃,1100℃);100μm group(the diameter of pore forming agent is 100μm,the content is 0%,10%,20%,30%);10μm group(the diameter of pore forming agent is 10μm,the content is 0%,10%,20%,30%).Porosity,pore structure and drug releasing process were studied by Archimedes-method,SEM and in vitro drug releasing experiment respectively.Then controlledβ-TCP artificial vertebral bodies with different controlled layer were soaked in PBS solution to investigate the releasing processes after measuring their mechanical strength.Results: Sintering temperature and pore forming agent could change the structure and the releasing process of controlled β-TCP layers.With the increasing of sintering temperature,diameter and content of pore forming agent,the compression strength decreased,the porosity and the releasing rate increased.The releasing rate of both 10μm and 100μm groups increased steadily.The compression strength of the drug controlled β-TCP artificial vertebral body was 3.19±0.15 Mpa.The cumulative release of 100μm groups were 6.66%、7.81%、8.82%、9.80% respectively;the cumulative release of 10μm groups were 6.66%、9.15%、11.76% and 16.46%.The releasing process was stable without burst release.Conclusions: The pore structure of controlled layer could change its property and drug releasing rate.The controlled β-TCP artificial vertebral body had good mechanical strength.The releasing process was stable and could last for a long time under simulated body fluid condition after the RFP loaded.The concentration of RFP was beyond the minimum bactericidal concentration.It could have the potential use in the treatment of bone defect with infection.