Selective Laser Melting of Integrated Ti6Al4V ELI Permeable Walls for Controlled Drug Delivery of Vancomycin

Abstract

Bacteria colonizing the surface of orthopedic implants are responsible for most postoperative periprosthetic joint infections. A possible alternative route for drug delivery is described in this study by utilizing the bulk of the implant itself as a reservoir. Drug release is enabled by manufacturing of integrated permeable structures possessing high porosity through application of selective laser melting technology. The concept was evaluated in two paths, with 400 μm permeable thin walls and with dense reservoirs containing an integrated 950 μm permeable wall. Components were designed and preprocessed as separate parts, allowing for allocation of different settings of laser power and scanning speed. Lowering the energy input into the selective laser melting process to induce intermittent melting of the Ti6Al4V ELI powder produced porous components through which vancomycin was released with differing profiles. Static water contact angle measurements demonstrated a significant effect on the hydrophilicity by permeable wall thickness. Relative porosities of the 400 μm structures were determined with microcomputed tomography analyses. A transition zone of 21.17% porosity was identified where release profiles change from porosity-dependent to near free diffusion. Antimicrobial activity of released vancomycin was confirmed through evaluation against Staphylococcus aureus Xen 36 in two separate agar diffusion assays. The approach is promising for incorporation into the design and manufacturing of next-generation prosthetic implants with controlled release of antibiotics in situ and the subsequent prevention of periprosthetic joint infections.

A review onin vitro/in vivoresponse of additively manufactured Ti–6Al–4V alloy

“…With the benefit of computer design in AM techniques, various architectures to create reservoirs of antibacterial agents, including simple lattice, gradient porosity, and microchannelcontaining structures, can be applied to the fabrication of Ti64 implants. [425][426][427] By exploiting AM methods' design flexibility in creating porous channels, Cox et al fabricated antibiotic-loaded Ti64 implants using a special injectable cement formulation. 428 In this study, after designing hole geometry and fabrication of implants using the SLM method, gentamicin was incorporated in brushite and CaP cement as a carrier vehicle, and the paste was injected into the holes.…”

Toward Bactericidal Enhancement of Additively Manufactured Titanium Implants

“…AM technology can also provide thin permeable walls with different porosities for hollow Ti implants. With the increase in porosity, the pattern of drug release profiles changes [88]. The filling material plays a pivotal role in the release spectrum, and its material type and solubility affect the reaction; for example, drugs with a higher water solubility exhibit a faster drug release rate [84].…”

“…The drug loading and drug eluting of these hollow Ti implants had promising antibacterial effects [85,88,90], which indicates that an optimized drug release profile could be achieved by rational structural design; however, a complete design scheme has not been proposed to date.…”

Additive Manufacturing Technologies for Drug Delivery Applications

“…Reservoir (Bezuidenhout et al, 2018;Cox et al, 2016; (Guo and Li, 2016;Liu et al, 2016;Lv et al, 2015)…”