Inkjet printed antibiotic- and calcium-eluting bioresorbable nanocomposite micropatterns for orthopedic implants

Inkjet printing of antibiotic- and calcium-eluting micropatterns was explored as a novel means of preventing the formation of biofilm colonies and facilitating osteogenic cell development on orthopedic implant surfaces. The micropatterns consisted of a periodic array of ∼50 μm circular dots separated by ∼150 μm. The composition of the micropatterns was controlled by formulating inks with rifampicin (RFP) and poly(D,L-lactic-co-glycolic) acid (PLGA) dissolved in an organic solvent with ∼100 nm biphasic calcium phosphate (BCP) nanoparticles suspended in the solution. During printing RFP and PLGA co-precipitated to form a nanocomposite structure with ∼10-100 nm RFP and the BCP particles dispersed in the PLGA matrix. The rate of RFP release was strongly influenced by the RFP loading in the micropattern, particularly on the first day. The RFP-containing micropatterns effectively prevented the formation of Staphylococcus epidermidis biofilm colonies due to their ability to kill bacteria prior to forming colonies on the patterned surfaces. The BCP-containing micropatterns printed on the surface of the alloy TiAl6V4 significantly accelerated osteoblast cell differentiation, as measured by alkaline phosphatase expression and calcium deposition, without compromising cell proliferation.