Construction and Osteogenic Properties of Plasma-Assisted Nano-Coating

In recent years, polyethylene terephthalate (PET) based Ligament Advanced Reinforcement System(LARS) artificial ligaments have become popular in anterior cruciate ligament (ACL) reconstruction. However, due to its poor biological activity and high hydrophobicity, its application is limited to clinical uses. In order to improve the biological activity of materials and enhance the tendon-bone healing effect, oxygen plasma was used to introduce hydroxyl groups on the surface of PET. It has been found that the surface physiochemical treatment and immobilization of bioactive molecules have great effects on the bioactivity improvement of the inert surfaces. Therefore, bone morphogenetic proteins (rhBMP-2) with typical indicator and fibronectin (Fn) for enhancing the binding capacity of rhBMP-2 molecules were chosen as modifying molecules. The functional molecules such as epigallocatechin-3-gallate (EGCG) were coated on the PET surface first. There are six ortho phenolic hydroxyl groups in the molecular structure of EGCG. Fn molecules were then easily immobilized on the EGCG-PET surfaces. Since each subunit of Fn had a high-affinity binding site for rhBMP-2, rhBMP-2 molecules are biological anchored on the surface through long-chained Fn, which simulates the biomimetic design in the extracellular matrix. Thus, such molecules EGCG, Fn, and rhBMP-2 are sequentially immobilized on the PET surfaces. The nanocoating of rhBMP-2/EGCG/Fn is assembled to further enhance the loading efficiency of rhBMP-2 and control the release of rhBMP-2. Therefore, the surface-modified B/E-Fn-PET exhibits excellent cell compatibility. Moreover, effective loading, activity maintaining, and controlled release of rhBMP-2 give the implant surface high osteoinduction and better osteogenesis. Predictably, the integrated influences of these factors will provide technical support for designing the insert implantable surface with high bioactivities.