Blood Compatibility Evaluation Of Iron-based Biomaterials And Its Application As Vaccine Delivery System

With the rapid development of medical nanomaterials,more and more iron-based nanomaterials have been designed for clinical medical treatment by scientists.Iron-based nanomaterials have many innovative features on the basis of traditional nanomaterials,and some have even been used in clinical medical applications,including biological sensing,imaging,cell labeling and drug delivery.In this study,a kind of iron-based material,iron polyphenols(TA-Fe³⁺),which has been widely used in the field of drug carriers in recent years,was prepared by us.Through a series of evaluation methods,TA-Fe³⁺and its degradation product,tannic acid?TA?,were tested for in-depth blood compatibility evaluation.In addition,a new type of pneumonia immunologic agents PLY_H@Fe?OH?₃ was prepared by ferric hydroxide?Fe?OH?₃?and attenuated Streptococcus pneumoniae hemolysin?PLY_H?to enhance cellular immunity.1.Evaluation of blood compatibility of tannic acidDue to the degradation characteristics of TA-Fe³⁺,a comprehensive evaluation of the blood compatibility of TA is beneficial to the further exploration between TA-Fe³⁺and human blood.The effect of TA concentration on the morphology and hemolysis of red blood cells?RBCs?was tested.It was found that high concentration of TA can cause RBCs to shrink,prick and hemolysis.The results of spectroscopy showed that TA had an effect on the structure and conformation of fibrinogen.High concentration of TA can shorten the activating partial thromboplastin time and plasma prothrombin time.TA also has a effect on the reaction time,coagulation time,clot aggregation speed and the maximum clot strength.These findings provide an important basis for the design of TA in metal polyphenol structure or other compound molecules and its application in biomedical field.2.Evaluation of blood compatibility of TA-Fe³⁺It was found out that TA-Fe³⁺and its degradation product Fe³⁺can interact with RBC,affect the morphology of RBCs and cause hemolysis of RBCs.Among them,the formation of TA-Fe³⁺in different ways will have different effects on the hemolysis of RBCs.Activated partial thromboplastin time,prothrombin time and thromboelastography showed that TA-Fe³⁺could affect the coagulation system.In addition,a variety of feeding methods on TA-Fe³⁺were used to conduct anti-A,anti-B coagulation experiments and hypotonic hemolysis experiments.The results showed that TA-Fe³⁺complex could not only envelop RBCs,but also shield the specific epitopes of red blood cells from antigen antibody reaction,and protect RBCs from the influence of hypotonic environment.3.The effect of PLYH@Fe?OH?3 immunologic agent on cellular immunityIn this study,PLY_H nanoparticles were prepared by heating and quenching the Streptococcus pneumoniae hemolysin?PLY?.Combined with Fe?OH?₃,PLY_H@Fe?OH?₃was prepared.The toxicity of PLY to RBCs was significantly reduced after heating and quenching.The results showed that PLY_H could stimulate spleen cell proliferation,central memory T cell differentiation and antigen-presenting cell activation better than PLY,so as to trigger stronger cellular immune response.In addition,the results showed that the specific immune response of the body to antigens could be further enhanced on the basis of PLY and PLY_H after combined with Fe?OH?₃ adjuvant.Therefore,Fe?OH?₃ has potential in the field of vaccine adjuvant,which can change and enhance the immune effect of immunologic agent.