Increased osteoblast cell density on nanostructured PLGA-coated nanostructured titanium for orthopedic applications

Abstract

There are more than 30,000 orthopedic implant revision surgeries necessary each year in part due to poor implant fixation with juxtaposed bone. A further emphasis on the current problems associated with insufficient bone implant performance is the fact that many patients are receiving hip implants earlier in life, remaining active older, and that the human lifespan is continuously increasing. Collectively, it is clear that there is a strong clinical need to improve implant performance through proper, prolonged fixation. For these reasons, the objective of the present in vitro study was to improve the performance of titanium (Ti), one of the most popular orthopedic implant materials. Accordingly, the proliferative response of osteoblasts (bone-forming cells) on novel nanostructured Ti/PLGA (poly-lactic-co-glycolic acid) composites was examined. This study showed that nano-topography can be easily applied to Ti (through anodization) and porous PLGA (through NaOH chemical etching) to enhance osteoblast cell proliferation which may lead to better orthopedic implant performance. This straight forward application of nano-topography on current bone implant materials represents a new direction in the design of enhanced biomaterials for the orthopedic industry.

Figure 1

SEM image of micron-sized wells formed on a Ti substrate using electrical discharge machining (EDM). This is the microTi substrate. Scale bar = 1 mm.

Figures 2

(A) 2500X SEM image showing the irregular micron-sized surface features on the microTi substrate (Scale bar = 10 μm). (B) 10,000X SEM image showing the irregular micron-sized surface features on the microTi substrate (Scale bar = 1 μm).

Figures 3

SEM images of anodized Ti substrates. Nano-scale surface features were evident, demonstrating that anodization created a nano-topography on Ti. Ti substrates were anodized in 5% hydrofluoric acid for 20 minutes at 10V. ((A): Scale bar = 10 μm; (B): Scale bar = 1 μm). These are the nanoTi substrates.

Figure 4

(A) SEM image of unetched porous PLGA coating on nanoTi (Scale bar = 100 μm). (B) SEM image of etched porous PLGA coating on nanoTi showing numerous micron-sized surface features (Scale bar = 100 μm). (C) SEM image of unetched porous PLGA coating on nanoTi (Scale bar = 1 μm). (D) SEM image of etched porous PLGA coating on nanoTi showing numerous nano-sized surface features (Scale bar = 1 μm). (B and D) are the nanoTi-nanoP substrate.

Figure 5

Increased osteoblast adhesion on nano-rough anodized Ti (nanoTi) and nano-rough etched PLGA coatings on nanoTi (nanoTi-nanoP). Data was normalized to etched glass reference. Data = mean +/− SEM; n = 6; * p < 0.05 (compared to unanodized Ti without PLGA or microTi).