Electric Field-Mediated Fibronectin–Hydroxyapatite Interaction: A Molecular Insight

Abstract

In experimental research-driven biomaterials science, the influence of different material properties (elastic stiffness, surface energy, etc.) and, to a relatively lesser extent, biophysical stimulation (electric/magnetic) on cell−material interactions has been extensively investigated. Despite the central importance of protein adsorption on cell−material interactions, the quantitative analysis to probe into the role of physicochemical factors in protein adsorption remains largely unexplored in biomaterials science. In recent studies, the critical role of electric field stimulation toward the modulation of cell functionality in implantable biomaterials has been experimentally demonstrated. Given this background, we investigated the influence of external electric field stimulation (upto 1.00 V/nm) on fibronectin (FN) adsorption on a hydroxyapatite (HA) (001) surface at 300 K using the all-atom molecular dynamics (MD) simulation method. FN adsorption was found to be governed by attractive electrostatic interactions, which changed with the electric field strength. Nonmonotonous changes in the structural integrity of FN were recorded with the change in the field strength and direction. This can be attributed to the spatial rearrangement of the positions of local charges and the global structural changes of proteins. The dipole moment vectors of FN, water, and HA quantitatively exhibited a similar pattern of orienting themselves parallel to the field direction, with field strength-dependent increase in their magnitudes. No significant change has been recorded for the radial distribution function of water surrounding FN. Field-dependent variation in the salt bridge nets and the number of hydrogen bonds between FN and HA were also examined. One of the important results in the context of cell−material interaction is that the RGD (Arg-Gly-Asp) sequence of FN was exposed to the solvent side when the field was applied along an outward direction perpendicular to the HA (001) surface. In summary, the present study provides molecular insights into the influence of electric field stimulation on phenomenological interactions involved in FN adsorption on the HA surface.

Computational study on Strontium ion modified Fibronectin-Hydroxyapatite interaction

“…It is now well-known that not all residues of FN interact equally with HA surface. Similar to our previous study, 31 the charged residues were found to be interacting more strongly with the surface (and Fig. S5 and S6 in supporting information) and have been listed in Table 2.…”

“…Another important aspect in the context of adsorption phenomena is the protein-surface distance as a higher protein-surface distance indicates a weakly adsorbed or desorbed state. 31 In the present study, the distance between the centre of mass (COM) of FN and surface has been computed together with the minimum distance between them (Fig 3(a)). The minimum distance is defined as the minimum of all the atomic pair distances, where one atom of the pair belongs to FN and other belongs to the surface.…”

“…28,27 Similar findings were reported for another important extracellular matrix protein, fibronectin (FN). 29,30,31 FN is a dimer protein consists of three types of FN repeats, namely FNI, FNII and FNIII. 32 While the long-range coulombic attraction was established to the driving force behind the adhesion of FNIII10 module on HA (001) surface, 29 Van der Waals (VDW) force driven weak adsorbed state was observed in case of FNIII7-10 module.…”

Molecular dynamic simulation of prenucleation of apatite at a type I collagen template: ion association and mineralization control

“…INTERFACE force field (IFF) was used to establish interaction between the calcium/phosphate and collagen protein in the aqueous phase. [58][59][60] The first 100 ps MD simulation was used for system heating up to 310 K in the isothermal-isobaric ensemble. The next 30 ns MD simulation was performed for the data analyses in the canonical ensemble (NVT) with the integration time step of 2 fs.…”

Molecular understanding of acetylcholinesterase adsorption on functionalized carbon nanotubes for enzymatic biosensors

“…With the development of modern computational technology, molecular dynamics simulation has become a powerful tool for studying the interaction between the protein and material surface at the atomistic level. 62–64 However, so far, the adsorption mechanism of acetylcholinesterase on the functionalized CNTs has not been reported. In this work, the parallel tempering Monte Carlo (PTMC) 65 and all-atom molecular dynamics (AAMD) simulations were employed to study the adsorption mechanism of acetylcholinesterase on the surfaces of NH 2 –CNT, COOH–CNT and pristine CNT.…”