Impact of 3D Hierarchical Nanostructures on the Antibacterial Efficacy of a Bacteria-Triggered Self-Defensive Antibiotic Coating

Abstract

Titanium is often applied in implant surgery, but frequently implicated in infections associated with bacterial adhesion and growth on the implant surface. Here, we show that hierarchical nanostructuring of titanium and the subsequent coating of resulting topographical features with a self-defensive, antibacterial layer-by-layer (LbL) film enables a synergistic action of hierarchical nanotopography and localized, bacteria-triggered antibiotic release to dramatically enhance the antibacterial efficiency of surfaces. Although sole nanostructuring of titanium substrates did not significantly affect adhesion and growth of Staphylococcus aureus, the coating of 3D-nanopillared substrates with an ultrathin tannic acid/gentamicin (TA/G) LbL film resulted in a 10-fold reduction of the number of surface-attached bacteria. This effect is attributed to the enlarged surface area of the nanostructured coating available for localized bacteria-triggered release of antibiotics, as well as to the lower bacterial adhesion forces resulting in subsided activation of bacterial antibiotic-defense mechanisms when bacteria land on nanopillar tips. The result shows that a combination of 3D nanostructuring with a bacteria-triggered antibiotic-releasing coating presents a unique way to dramatically enhance antibacterial efficacy of biomaterial implants.

Gentamicin coating of plasma chemical oxidized titanium alloy prevents implant-related osteomyelitis in rats

“…Payne et al were able to detect the mode of action of tannic acid: biofilm formation is inhibited via a mechanism dependent upon the putative transglycosylase IsaA [27]. Therefore, the combination of tannic acid and gentamicin could lead to a synergistic antibacterial and anti-biofilm formation effect [28]. The advantage of our surface modifications is the antibacterial effect in combination with improved osseointegration, as recently reported for the bioactive TiOB surface [14].…”

Silver Nanocoating Technology in the Prevention of Prosthetic Joint Infection

“…Consequently, the nanoscale surface patterning methods have been applied to fabricate different nanopatterns (e.g., ordered stripes, pits, pillars or squares). Several studies have demonstrated that nanopatterning in conjunction with other surface treatment can inhibit bacterial adhesion [152,153]. …”

Decreased bacterial growth on titanium nanoscale topographies created by ion beam assisted evaporation

“…Implants can, however, be treated to encourage cell integration, and numerous coating processes have been tested as a way to improve bone integration and biological adaptivity of titanium. [2][3][4][5] However, other than using systemic antibiotic delivery, there are few options clinically available to decrease the growing rate of infected orthopedic implants. Many groups have incorporated antibiotics directly into layered coatings on top of titanium surfaces, 4,5 but the coating adhesion may not survive the wear that titanium implants can experience during handling, implantation and use.…”

“…[2][3][4][5] However, other than using systemic antibiotic delivery, there are few options clinically available to decrease the growing rate of infected orthopedic implants. Many groups have incorporated antibiotics directly into layered coatings on top of titanium surfaces, 4,5 but the coating adhesion may not survive the wear that titanium implants can experience during handling, implantation and use. In the research community, the advent of nanoscale titanium texturing has resulted in improved osseointegration and decreased bacterial presence.…”