Preparation Of Antibiotic-loaded Copper-doped Hydroxyapatite Microspheres And Evaluation Of Their Biological Properties

Chronic osteomyelitis is mainly a chronic disease caused by purulent bacterial infection.The treatment cycle of the disease is prolonged and the clinical treatment effect is unsatisfactory.The occurrence and development of osteomyelitis are inseparable from the formation,adhesion and aggregation of bacterial biofilm in the early stage.It is the key to effectively destroy or inhibit the formation of bacterial biofilm in the early stage.Early infusion of antibiotics is a routine preventive measure,but intravenous infusion of antibiotics cannot be used for a long time.It will cause serious systemic toxic reactions,especially the damage to the kidneys,and increase the resistance of bacteria.Therefore,the use of the antibacterial drug slow-release system to quickly reach the peak concentration of the drug in the local tissues can prevent high-concentration antibacterial drugs from entering the blood and reduce the adverse effects of systemic administration.It is an effective method for the treatment of chronic osteomyelitis.At present,microsphere drug-loaded sustained-release systems are a hot topic,and finding suitable microsphere materials has become a problem worthy of consideration.Hydroxyapatite（HA）is the main inorganic component of the bones of humans and even all mammals;copper is an important trace element in the life of mammals,which can enhance the activity of various enzymes.The bioactive glass added with copper element shows stronger antibacterial activity than the one without addition,and at the same time has the function of promoting angiogenesis,which is beneficial to the formation and growth of new bone.Inspired by marine organisms,polydopamine（PDA）has super adhesion,excellent hydrophilicity and biocompatibility,so it can be used as a carrier for antibiotics to compound with copper-doped hydroxyapatite.The PDA is expected to achieve the dual effects of local inorganic ions antibacterial and antibiotics,and improve the biological properties of copper-doped hydroxyapatite.The investigation found that the drug-loading of microspheres is the focus of recent research,but there are few reports about the copper ion-controlled hydroxyapatite loading vancomycin,and most antibacterial materials only pay attention to the antibacterial effect for a while,and rarely compare the antibacterial effect for a period of time.Moreover,the biocompatibility of copper ion-doped materials has not been improved.Therefore,in this subject,relying on the super adhesion and good biocompatibility of polydopamine,it is used as an intermediate medium to connect vancomycin and copper-doped hydroxyapatite,improve the antibacterial and osteogenic effects of copper-doped hydroxyapatite,improve biocompatibility,and have the ability to load vancomycin and release it slowly.The main research content and results include:（1）Using the method of hydrothermal synthesis,using copper as the doping source,using coated polydopamine combined with vancomycin,a polydopamine-coated vancomycin-containing copper-doped hydroxyapatite（Cu-HA-PDA-Van）.Explore the micro-nano morphology,crystal structure,and chemical composition of the synthesized undoped HA and Cu doping ratios of 1%,5%,10%,and 20%HA samples.The results show that different Cu element doping ratios have different effects on the surface morphology of HA.10%Cu doped HA and 20%Cu doped HA particles show petal-like microspheres,but10%Cu doped HA has a smaller particle size and can make less The Cu²⁺precipitates out,thereby reducing the toxic effect of Cu²⁺.The addition of polydopamine and Cu²⁺will not change the crystal structure of HA,and the crystallinity will be slightly reduced.（2）Explore the toxic effects of HA,HA-PDA,Cu-HA,Cu-HA-PDA-Van extracts on osteoblast precursor cells MC3T3-E1.The results show that when the concentration is 50mg/m L,the group Cu-HA The extract showed certain cytotoxicity,and the 10mg/ml extract showed good biocompatibility in each group.The proliferation activity of SD-rat bone marrow mesenchymal stem cells（BMSCs）was tested using the 10mg/m L extract,which proved that the addition of PDA increased the biological activity of each group of materials,while Cu²⁺had no effect on the proliferation of BMSCs.obvious.At the same time,the effect on the osteogenic differentiation of bone marrow mesenchymal stem cells（BMSCs）was studied,indicating that Cu²⁺has the effect of promoting osteogenic differentiation.（3）The results of co-cultivation of HA,HA-PDA,Cu-HA,Cu-HA-PDA,Cu-HA-PDA-Van and Staphylococcus aureus proved that Cu²⁺has a certain inhibitory effect on the growth of bacteria,and the load Vancomycin（Cu-HA-PDA-Van）group has obvious antibacterial effect,and has a lasting antibacterial effect for 7 consecutive days.In summary,the Cu element was successfully doped into HA in the form of ions or groups,and the surface morphology of HA was directionally controlled.Cu-HA-PDA-Van microspheres can enhance the activity of cells and promote the directional osteogenic differentiation of stem cells.At the same time,Cu-HA-PDA-Van microspheres have a strong inhibitory effect on bacterial growth.The microspheres studied in this subject can block the formation of bacterial biofilm in the early stage of chronic osteomyelitis,prevent the eventual occurrence of the disease,and provide a new alternative material in the treatment of bone defects.