The Construction Of Chemotaxis Surface On Titanium Implant And Controled Release Evaluation Of SDF-1

Objective:biomolecule surface modifcation on titanium surface provides a effective strategy toconstructure bioactive implant and has been a highlight on titanium surface treatmentin recent years. Polyelectrolyte complex film was constucted by alternating depositionheparin and chitosan on titanium surface called layer by layer self-assembly technique.Meanwhile, stromal derived factor-1(SDF-1) was loaded on the modified layers,aiming to increase the quantity of bioactive molecules and realize their controlledrelease effect. The modified titanium implant presents higher bioactivity and promotesbone healing.Methods:the titanium substrate was first polished and ultrasonically cleaned in acetone, ethanol,and deionized water. After the species are dried, they were treated by NaOH solution toproduce porous, hydroxyl group-rich surface. The positive charged poly-L-lysine (PLL)layer was then adsorbed on the modified substrate. The multilayer was then formed byalternating deposition of negative charged heparin (HEP), and positive chargedchitosan (CHI), SDF-1. herein chemotaxis inductive biointerface was generated ontitanium surface by loading SDF-1. Afterwards the treated Ti foils were immersed innormal saline in1.5ml EP tubes.1d,3d,5d,7d were selected as time point, at whichtime the incubation medium normal saline were collected and refreshed. All thecollected medium were cryopreservation and the release SDF-1was measured byenzyme-linked immunosorbent assay (ELISA). We used EXCEL to draw standardcurve according to data, and tested in single factor analysis of variance. Results:1) SEM images present that the titanium surface treated with NaOH had networksstructure at micor-nano scale. The heparin and chitosan moledule were well-distributedon the surface of Ti. The coating that existed completely in spite of immersion for7days under SEM suggested its stability.2) single factor analysis of variance provides the information that there is no statisticaldifference between4groups in releasing concentration was tested at different timepoint (F=1.139,P=0.582), as well as data for each day (F=1.644,P=0.231) and eachgroup(F=0.689,P=0.576)Conclusion：1) The chemokines SDF-1, heparin and chitosan were successfully absorbed on thesubstrate titanium using layer by layer self-assembly technique. The coating wasprepared successfully under the scanning electron microscope.2) Concertration of SDF-1was measured by enzyme-linked immunosorbent assay(ELISA) and SDF-1was immobilized on the titanium and could be controlled releaseby self-assembly method.