  The contribution of electrostatic interactions to the free energy of binding
between model protein and a ceramic implant surface in the aqueous solvent,
considered in the framework of the non-local electrostatic model, is calculated
as a function of the implant low-frequency dielectric constant. We show that
the existence of a dynamically ordered (low-dielectric) interfacial solvent
layer at the protein-solvent and ceramic-solvent interface markedly increases
charging energy of the protein and ceramic implant, and consequently makes the
electrostatic contribution to the protein-ceramic binding energy more favorable
(attractive). Our analysis shows that the corresponding electrostatic energy
between protein and oxide ceramics depends non-monotonically on the dielectric
constant of ceramic. Obtained results indicate that protein can attract
electrostatically to the surface if ceramic material has a moderate dielectric
constant below or about 35 (in particularly ZrO2 or Ta2O5). This is in contrast
to classical (local) consideration of the solvent, which demonstrates an
unfavorable electrostatic interaction of protein with typical metal oxide
ceramic materials (dielectric constant>10). Thus, a solid implant coated by
combining oxide ceramic with a reduced dielectric constant can be beneficial to
strengthen the electrostatic binding of the protein-implant complex.
