Enhanced Synthesis Of Brushite Calcium Phosphate Cement: Investigating Improved Mechanical And Biological Properties

Brushite calcium phosphate cement（Bru-CPC）possesses favorable biocompatibility,degradability,processability,and suitable porosity,along with beneficial properties such as promoting cell adhesion and growth,making it a self-setting bioactive bone cement.However,its cured product exhibits inferior mechanical performance and uncontrollable degradation rate,which restricts the application of Bru-CPC bone repair material in weight-bearing bone and hard tissue repairs.To address this issue,this study employs polydopamine with good biogenic viscosity to modify montmorillonite（MMT）and halloysite nanotubes（HNTs）,which have a relatively large specific surface area and can partially substitute Bru-CPC.This seeks to improve both the mechanical and bioactivity properties of bone repair materials.The metastable dicalcium phosphate dihydrate,the curing product of Bru-CPC,is modified by dopamine and then composited with Bru-CPC in situ,further promoting improved mechanical performance and bioactivity.To further enhance the mechanical properties of bone repair materials,carboxyl-functionalized polyethylene glycol（PEG（COOH））is utilized for modification.Based on the chelation between carboxyl groups and calcium,an ideal mechanical performance Bru-CPC bone repair material is fabricated via liquid-phase compounding,while maintaining good bioactivity.Finally,HNTs were modified with ¹⁹F atom,achieving rapid ¹⁹F NMR detection under stimulating with hydrogen peroxide（H₂O₂）.This material has the potential to serve as an additive for bone repair materials,thereby achieving non-destructive monitoring and testing during the bone repair process.The main content is as follows:Firstly,employing chemical modification,polydopamine is grafted onto MMT and HNTs,which are then used as solid-phase additives incorporated into Bru-CPC bone repair materials.The resulting cured product exhibits a denser and more orderly crystal packing,with smaller grain sizes.The hollow structure of MMT and HNTs promotes cell proliferation,enhances ALP activity,and increases the expression levels of osteogenesis-related genes.The compressive strength were elevated to 16.58 MPa and 16.23 MPa,respectively.The study demonstrates that MMT@PDA and HNTs@PDA can serve as biocompatible materials,improving the mechanical and biological performance of Bru-CPC bone repair materials.Secondly,dopamine-modified partially hydrolyzed calcium hydrogen phosphate,an intermediate phase,is utilized as a solid-phase additive for in-situ composite incorporation with Bru-CPC bone repair materials.The results indicate that the composite bone repair material exhibits well-organized crystallization after curing,achieving a compressive strength of 22.05MPa for the modified bone cement.The modified cement also enhances biocompatibility,increases cell proliferation,particularly promoting early-stage osteogenic differentiation and ALP secretion.Thirdly,PEG（COOH）is prepared and dissolved in water to create a curing agent used in the solidification reaction of Bru-CPC bone repair materials.The effects of polyethylene glycol（PEG）and PEG（COOH）on the preparation process,microstructure,mechanical properties,and biological performance of Bru-CPC bone repair materials are investigated.The addition of an appropriate amount of PEG（COOH）effectively improves the microstructure of Bru-CPC bone repair materials,enhances injectability and mechanical performance,resulting in a compressive strength of 30.19 MPa.This addition also upregulates the expression of osteogenesis-related gene markers and enhances ALP activity,achieving the experimental design of this chapter.Fourthly,bone defects often involve abnormal levels of inflammation and reactive oxygen species（ROS）in the defect site,which hinder bone repair.H₂O₂ can serve as a visual marker for detecting related pathologies.In this section,functional halloysite nanotube probes modified with ¹⁹F（HNTs-6FBBs）are prepared,and rapid ¹⁹F NMR detection is achieved under reactive oxygen species（hydrogen peroxide）stimulation.The relationship between H₂O₂ and ¹⁹F NMR is studied,providing a novel approach for diagnosing H₂O₂-related pathologies.This material holds the potential to serve as an additive for bone repair materials,incorporated into Bru-CPC bone repair materials,thereby enabling non-destructive monitoring and detection during the bone repair process.