Serum albumin and chondroadherin interact with graphene oxide coating of orthopedic implant; computational insights

3 Abstract: The interactions of blood and joint components with the material of implants used in orthopedics are crucial. Orthopedic implants are widely used in knee and joint replacement surgeries. Ideally, implant surfaces should enhance osteoblast functions and simultaneously inhibit microbial infection, however, unfavourable serum protein-material interactions may cause clinically intractable infections and implant failure. Despite several attempts to overcome such consequences to physicochemical properties of materials, implant failures do exist significantly. Therefore, profiling molecular-level interactions between human serum proteins and implant material is vital in subsequent protein-material behaviour. Graphene oxide (GO) is one such orthopedic implant material that has been gaining attention in bio-tribology. Present molecular docking simulations report the interacting behavior of serum albumin (SA) and chondroadherin (CHAD) with the GO-based orthopedic implant coating. It was aimed to elucidate binding affinities and molecular-level interactions at the proteins-material interface. Considering the most stable conformations, the strongest binding affinities of SA-GO and CHAD-GO interactions were calculated to be - 10.3 kcal/ mol and -12.3 kcal/ mol respectively. Analysis of all binding modes showed that CHAD has the highest overall affinity towards GO. Root mean square deviation was consistent with the modes. Only conventional hydrogen bonding was predominant in SA-GO complex while CHAD-GO complex is heavily influenced by both the hydrogen bonding and hydrophobic interactions involving π orbitals. Though CHAD seems competitive, it developed steric hindrance at the interacting surface while there were no such effects with SA interactions at the GO surface. These interaction trends establish the requirement for experimental analysis.