Abstract
The interaction between bone morphogenetic protein-2 (BMP-2) and the surface of biomaterials is essential for the restoration of bone and cartilage tissue, inducing cellular differentiation and proliferation. The properties of the surface, including topology features, regulate the conformation and bioactivity of the protein. In this research, we investigated the influence of nanopatterned surfaces on the interaction of a homodimer BMP-2 with graphite material by combining molecular dynamics (MD) and steered molecular dynamics (SMD) simulations. The graphite substrates were patterned as flat, linear grating, square, and circular profiles in combination with BMP-2 conformation in the side-on configuration. Ramachandran plots for the wrist and knuckle epitopes indicated no steric hindrances and provided binding sites to type I and type II receptors. Results showed two optimal patterns that increased protein adsorption of the lower monomer while preserving the secondary structure and leaving the upper monomer free to interact with the cells. Charged residues arginine and lysine and polar residues histidine and tyrosine were the main residues responsible for the strong interaction with the graphite surface. This research provides new molecular-level insights to further understand the mechanisms underlying protein adsorption on nanoscale patterned substrates.
Highlights
The interfacial phenomenon directly affects the effectiveness of biomedical devices.Surface properties of biomaterials guide essential in vivo functions, including protein adsorption, cell adhesion, and inflammatory responses [1]
Additional binding sites were located on the sidewalls of Circular slot 2 (CS2) and SQ profiles, which contributed to the adsorption energies
In our previous study [34], in which we evaluated the effects of different initial orientations of a monomer bone morphogenetic protein-2 (BMP-2) onto graphite on the adsorption behavior, similar residues were responsible for adsorption on flat graphite, including Tyr, His, Arg, Val, and Lys
Summary
Surface properties of biomaterials guide essential in vivo functions, including protein adsorption, cell adhesion, and inflammatory responses [1]. The modification and functionalization of biomaterials allow the development of an adequate physical and chemical environment, inducing specific cellular functions and stimuli-responsive release [1,2]. The three-dimensional structure of the extracellular matrix provides specific signals that induce cellular development [2,3]. One of the critical issues in tissue engineering-based treatment is to obtain an efficient delivery of the proteins to the injury site [6–8]. This delivery has a weak tissue penetration, an uncontrollable migration, and incompetent internalization of cells due to the enzymatic degradation of the extracellular matrix [9]. Understanding the interaction of these signals with biomaterials is essential to improve cell growth
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