Surface Functionalization Of Monodisperse Hydroxyapatite Nanocrystals And Their Biological Applications

Hydroxyapatite(Ca₁₀?PO₄?₆?OH?₂,HAp)is the main inorganic component in human hard tissues.Its chemical composition and crystal structure are very close to the main inorganic components in biological bone and enamel.HAp has great application potential in the fields of bone tissue engineering regeneration and reconstruction,separation and purification of biomacromolecules,carriers for drug release,anti-tumor,and chemical catalysts,etc.However,there are still a lot of challenges in its practical application.For example,it is difficult to obtain HAp materials that have both desirable crystal purity and grain size and outstanding water dispersibility.These problems have severely limited the further development and application of HAp nanomaterials.In this paper,doping modification and surface functionalization have been performed for HAp nanomaterials synthesized by hydrothermal method based on liquid-solid-solution?LSS?strategy.HAp nanomaterials with good water dispersibility,biocompatibility and fluorescence properties have been synthesized by different methods.Furthermore,their biocompatibility and cell uptake behaviors were examined and their potential for applications in the field of cell imaging were explored.1.Europium ion doped HAp nanorods were first synthesized by hydrothermal method.Then the polymers of 2-methacryloyloxyethylphosphorylcholine?MPC?were grafted on the HAp surface by metal-free atom transfer radical polymerization?ATRP?method.The HAp nanomaterials modified by hydrophilic polymers?HAp-polyMPC?were obtained.The modified HAp maintained its good morphology.It can disperse in water for up to 12 h and hardly precipitate.The results of cell compatibility evaluation showed that HAp-polyMPC has good cell compatibility and cell uptake behavior,and then successfully applied to cell imaging.2.Polyethylene glycol methacrylate?PEGMA?with good biocompatibility and hydrophilic properties was used as monomer,to modify the HAp nanomaterials doped with rare earth ions by photo-RAFT polymerization method.The fluorescent HAp nanomaterial with good water dispersibility?HAp-polyPEGMA?was obtained.Based on the good properties of modified HAp nanomaterials,its application in cell imaging has been successfully explored.3.Based on the multifunctional organic fluorophore,the HAp materials were constructed by a one-pot free radical polymerization:The multifunctional organic polymer fluorescent dyes were bonded to the surface of the HAp material by ligand exchange reaction.Then,using PEGMA as monomers,the metal-free ATRP method was used to initiate polymerization of the monomers on the surface of the material.Finally,HAp nanomaterials with excellent fluorescent properties and good water dispersibility were obtained.And further explored its application in cell imaging.4.Preparation of functional fluorescent HAp based on supramolecular chemistry:Using the nature of supramolecular host-guest self-assembly between?-cyclodextrin-hyperbranched glycidol??-CD-HPG?and hydroxyapatite-adamantane?HAp-Ad?,?-CD-HPG could form an exact 1:1 inclusion complex with HAp-Ad via host-guest interaction.Finally,the fluorescent HAp?HAp-?-CD-HPG?with excellent water dispersibility was prepared.