Collagen Coating of Titanium Implants Using Nonthermal Plasma

Surface modification of implants is now an essential aspect of biocompatibility. A single-step process to attach biomolecules to implants represents a major advance, and plasma coating potentially achieves this. An aqueous solution of collagen was sprayed into a nonthermal plasma and deposited onto titanium surfaces. The plasma instantly transformed the liquid aerosol into a coagulated dry coating on the implant surface. Surface analysis confirmed the presence of a thin, conformal protein layer on the metal surface. Titanium fixation screws were coated first with hydroxyapatite and then with a layer of collagen and were implanted into the femurs of New Zealand white rabbits and compared to various control surfaces. Measurements of the rotational torque removal force indicated that the collagen coating enhanced bone fixation and created a more reproducible well-anchored, stable implant than the traditional plasma-sprayed hydroxyapatite coatings. Nonthermal plasma processing offers a single step route to the biological functionalization of implantable surfaces. The process requires no polymers, primers, or linkers and offers an opportunity to control biocompatibility and to tailor local response to the implant in vivo. This opens the door to a wide variety of novel biological surface coatings across all aspects of life sciences and medicine.