Covalent grafting of titanium with a cathelicidin peptide produces an osteoblast compatible surface with antistaphylococcal activity

Abstract

Bacterial infection of orthopaedic implants, often caused by Staphylococcus species, may ultimately lead to implant failure. The development of infection-resistant, osteoblast-compatible biomaterials could represent an effective strategy to prevent bacterial colonization of implants, reducing the need for antibiotics.In this study, the widely used biomaterial titanium was functionalized with BMAP27(1–18), an α-helical cathelicidin antimicrobial peptide that retains potent staphylocidal activity when immobilized on agarose beads. A derivative bearing a short spacer with a free thiol at the N-terminus was coupled to silanized titanium disks via thiol-maleimide chemistry. Tethering was successful, as assessed by Contact angle, Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), and X-ray Photoelectron Spectroscopy (XPS), with an average surface mass density of 456 ng/cm2 and a layer thickness of 3 nm. The functionalized titanium displayed antimicrobial properties against a reference strain of Staphylococcus epidermidis with well-known biofilm forming capability. Reduction of bacterial counts and morphological alterations of adhering bacteria, upon 2 h incubation, indicate a rapid contact-killing effect. The immobilized peptide was not toxic to osteoblasts, which adhered and spread better on functionalized titanium when co-cultured with bacteria, compared to non-coated surfaces. Results suggest that functionalization of titanium with BMAP27(1–18) could be promising for prevention of bacterial colonization in bone graft applications.