Study On The Structure And In Vitro Performance Of 3D Printed Isoniazid Microspheres Modified Coaxial Bone Scaffold

Bone tuberculosis is a disease caused by conjugated bacilli in bones and joints.The treatment cycle is long,and long-term drug use is easy to cause organ damage such as liver.Drug carrier implantation can reduce the use of drugs and reduce the damage of drugs to the body.Bone tissue engineering scaffolds can be used as degradable scaffolds for bone defects.Combined with tuberculosis drugs,they can realize targeted treatment of the disease on the basis of bone repair.However,at the present stage,there are few researches on the control of drug release of stents and composite materials.And there are few researches on the quantitative control of stent drugs.So the drug and drug release amount of each stent cannot be well controlled.Therefore,based on the dose-effect relationship between the scaffold and the material.This paper carried out drug prediction processing on the scaffold.Controlled the drug loading of each scaffold,and reduced the error of the drug loading of the scaffold.On the basis of the bone tissue engineering scaffold.Drug microspheres were used to improve the drug release performance of the scaffold and 3D printing technology was combined to optimize the structure of the scaffold.So as to control the slow release and degradation performance of the scaffold.Therefore,the performance of the scaffold was investigated by microsphere content,microsphere carrying structure and drug release kinetics simulation.Firstly,in order to explore the influence of microsphere content on the performance of scaffolds.Microspheres with different contents were carried into the scaffold by embedding method,and the performance of the scaffold was tested by exploring drug loading,slow release and degradation experiments of the scaffold.The effect of microspheres on the performance of scaffolds was further revealed by observing the degradation of scaffolds under electron microscope.The experimental results showed that the microspheres with 6% drug content could slow down the sustained release rate of uniaxial scaffolds and accelerate the degradation rate of scaffolds.And the mechanical properties still met the requirements of cancellous bone.Therefore,microspheres can change the sustained-release characteristics of scaffolds,and optimize the degradation of scaffolds,and promote the repair of bone defects.Secondly,the effects of different structures of microspheres on the slow release,degradation and mechanical properties of the scaffold were investigated.Based on the uniaxial microsphere scaffold experiment.The coaxial internal and external core microsphere scaffold architecture was changed by 3D printing method.Using scaffold to control the drug release by construction.The experimental results show that the coaxial structure without microsphere can further control the drug release of the stent and slow down the drug release rate.If the outer core of the coaxial structure is loaded with balls,the degradation rate in the early stage will be increased and the sustained release rate will be accelerated,while the inner core loaded with microspheres will increase the degradation rate and the sustained release rate in the later stage.Through the coaxial mechanics experiment,it is concluded that the outer core structure of the stent determines the mechanical properties of the stent before degradation.The inner core determines the rate of change of the stent mechanics after degradation.Finally,in order to further interpret the sustained release behavior of the stent,kinetic equation fitting was carried out for the drug release behavior of the stent.The experimental results showed that the drug release modes of uniaxial and coaxial stents were both degradation and swelling,and spontaneous diffusion was the main drug release mode.After the release of the stent without burst release,it was found that the stent release method was consistent with the diffusion zero-order equation when it was slower,and matched with Peppas equation when it was faster.Experimental results show that the drug release modes of uniaxial and coaxial scaffolds are related to degradation and swelling.the addition of microspheres can further optimize the degradation and sustained-release properties of scaffolds on the basis of changing the porosity of scaffolds.