Grafted Adenosine Diphosphate And Fibrinogen On The Surface Of Titanium To Improve Platelet Activity

Objectives: Oral antiplatelet drugs are widely used for the treatment and prevention of patients with cardiovascular diseases.Because of dentition defect,many patients with cardiovascular diseases go for the dental-implant.The key to implants is osseointegration,where platelets play an important role in this process.The aim of the paper is to modify titanium surface by grafting the functional active substance adenosine diphosphate(ADP)and fibrinogen(FIB)onto the implant surfaces,which can promote platelet adhesion and aggregation activation,and improve the feasibility of osseointegration,and provide an experimental basis for the development of dental implants for patients who long-term use of antiplatelet drugs.Methods: Ti substrates were first modified through the poly-dopamine anchorage.Then,ADP and FIB were immobilized on the Ti substrates.This experiment was divided into four groups: pure titanium control group,ADP grafted group,FIB grafted group and ADP+FIB group.X-ray photoelectron spectroscopy(XPS)was performed to detect whether functional molecules were successfully grafted to Ti surface.The surface energy of the material was measured by static contact angle measurement.The adhesion of platelets was detected by scanning electron microscopy(SEM),and lactate dehydrogenase(LDH)quantitative assays.Whether platelets were active after adhesion and aggregation was detected by immunofluorescence marks assay.After culturing human mesenchymal stromal cells(hMSCs)on the grafted substrates,cytotoxicity was tested using a cell counting kit.Results: XPS showed that the coated surface possessed P peaks indicating the abundance of ADP,and S peaks indicating the abundance of FIB.Under SEM,there were large numbers of platelets-like cells gathered in clusters on coated surfaces compared with the controls.LDH results of four groups indicated the Ti-DOP-ADP-FIB significantly promote platelet adhesion than other groups(P<0.05).The immunofluorescence experiments indicated platelets were active largely.hMSCs proliferation results showed cell number of all four groups rose at different time points,however with no significant differences in 1,3 and 5 days(P>0.05).Conclusion: ADP and FIB can be successfully grafted onto titanium surface.And the ADP+FIB group can promote adhesion,aggregation and active of platelets and the release of bioactive molecules from platelets.Moreover,this modified Ti surface has been certified safety to hMSCs,and has potential for improved osseointegration of titanium dental implant.The coating can be an effective method to modify implant surface,which can be used for patients with the history of oral antiplatelet therapy to improve the ability of implant-bone integration.