Preparation And Properties Research Of Chitosan/Calcium Polyphosphate Composite Bioceramics

Calcium polyphosphate(CPP)bioceramic is expected to be applied in tissue engineering because of its mechanical properties,biocompatibility and osteo-conduction.As implanted scaffolds,CPP has drawbacks including fragility and low biodegradation rate.Composited CPP with other inorganic or organic materials are common methods to make up those disadvantages.As naturally polymer,chitosan is widely used in medicine,drug release and tissue engineering due to its good film-forming,biodegradability and biocompatibility.Composite chitosan with polymers or bioceramics including gelatin,collagen,polyacetic acid,calcium phosphate,and nano-hydroxyapatite have been studied.Few study composited chitosan with CPP.In this study,we prepared CS coating on CPP through immersion process.In this study,we studied CS/CPP composite bioceramics from the following aspects:firstly,efficient method to prepare chitosan solution has been discussed by studying the dissolution characteristic of chitosan in acetic acid solution.And optimized the process to obtain CS/CPP by immersing CPP into CS solution for different time along with ultrasonic concussion has been studied.Secondly,different types of CS/CPP have been prepared by altering the CS solution concentration,the CS viscosity,the structure of CPP and the ratio of CS/gelatin.The micro-topography,elements,contact angle,biodegradation and bioactivity in vitro of those composite CS/CPP materials have been discussed.Structure,physical and chemical properties and the interaction of composite CS/CPP have been characterized by XRD,EDS,XPS,FI-IR;analytical balance and so on.The biodegradation and bioactivity in vivo of those composite CS/CPP materials have been discussed through studying the weight loss,microtopography changes,element composition and group analysis after immersing in Tris-HCl solution and simulated body fluid(SBF)for different time.The results showed that the dissolve time of chitosan can be reduced about 3/4 by altering the order of adding chitosan and acetic acid.Immersing porous CPP into chitosan solution for different times,few influence on porosity,while weight gain,binding force and compressive strength tend to rise in the first stage,and then decrease along with the time increasing.,tripled the compressive strength.Immersion along with ultrasonic concussion helps chitosan solution enter the pores inner CPP,the optimized immersion method is 24h along with 10min ultrasonic concussion.The result of FI-IR,TGA and XPS showed that there exists interaction between CPP and CS.The influences of coating composition and matrix structure on degradation rate of composite bioceramics are as follows:when the matrix was gradient CPP,the degradation rate was accelerated after the addition of dibutyl phthalate in chitosan solution;the degradation rate first decreased and then increased along with the concentration of chitosan solution increased;the degradation rate was proportional to the viscosity of chitosan;the degradation rate first increased and then decreased along with the dibutyl phthalate addition increased;the degradation rate first increased and then decreased along with the ratio of CS/gelatin increased;And of all the composite mate:rials in the research,coating including ratio of CS/gelatin was 1:1,volume/mass ratio of dibutyl phthalate was 0.1 degraded fastest.When the matrix was single port CPP,the degradation rate of CS/CPP was inversely proportional to the ratio of stearic acid in CPP.Carbonated hydroxyapatite(Ca10(PO4)3(CO3)2(OH)2)was formed on the surface of composite bioceramics 6%CS/CPP(B4),CS(viscosity>200mPa.s(E2?E3),CS/gelatin(ratio 1:2)/CPP(F3)when soaked in SBF,which has proved the bioactivity of samples.