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Greater osteoblast proliferation on anodized nanotubular titanium upon electrical stimulation.

Ercan B, Webster TJ - Int J Nanomedicine (2008)

Bottom Line: Currently used orthopedic implants composed of titanium have a limited functional lifetime of only 10-15 years.One of the reasons for this persistent problem is the poor prolonged ability of titanium to remain bonded to juxtaposed bone.It has been proposed to modify titanium through anodization to create a novel nanotubular topography in order to improve cytocompatibility properties necessary for the prolonged attachment of orthopedic implants to surrounding bone.

View Article: PubMed Central - PubMed

Affiliation: Division of Engineering, Brown University, Providence, RI 02912, USA.

ABSTRACT
Currently used orthopedic implants composed of titanium have a limited functional lifetime of only 10-15 years. One of the reasons for this persistent problem is the poor prolonged ability of titanium to remain bonded to juxtaposed bone. It has been proposed to modify titanium through anodization to create a novel nanotubular topography in order to improve cytocompatibility properties necessary for the prolonged attachment of orthopedic implants to surrounding bone. Additionally, electrical stimulation has been used in orthopedics to heal bone non-unions and fractures in anatomically difficult to operate sites (such as the spine). In this study, these two approaches were combined as the efficacy of electrical stimulation to promote osteoblast (bone forming cell) density on anodized titanium was investigated. To do this, osteoblast proliferation experiments lasting up to 5 days were conducted as cells were stimulated with constant bipolar pulses at a frequency of 20 Hz and a pulse duration of 0.4 ms each day for 1 hour. The stimulation voltages were 1 V, 5 V, 10 V, and 15 V. Results showed for the first time that under electrical stimulation, osteoblast proliferation on anodized titanium was enhanced at lower voltages compared to what was observed on conventional (nonanodized) titanium. In addition, compared to nonstimulated conventional titanium, osteoblast proliferation was enhanced 72% after 5 days of culture on anodized nanotubular titanium at 15 V of electrical stimulation. Thus, results of this study suggest that coupling the positive influences of electrical stimulation and nanotubular features on anodized titanium may improve osteoblast responses necessary for enhanced orthopedic implant efficacy.

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Schematic of the anodization system.
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f1-ijn-3-477: Schematic of the anodization system.

Mentions: Afterwards, the surface cleaned titanium samples were etched with a 1.5% HF/1.5% HNO3 solution (Mallinckrodt Chemicals) for 5 minutes to remove the oxide layer. This was followed by an anodization process (Figure 1). For anodization, titanium samples were connected to a DC-powered electrochemical cell which had a two electrode configuration. A platinum mesh was used as the cathode and a titanium specimen was used as the anode. These platinum and titanium samples were connected to a DC power supply (3645A DC power supply, Circuit Specialists, Inc.) through copper wires. A constant voltage of 20 V was applied for 10 minutes according to previous studies (Yao et al 2005). The distance between the titanium anode and platinum cathode was kept constant at 1 cm. The electrolyte solution used in this study was 1.5% hydrofluoric acid and the anodization was conducted inside a Teflon beaker. During anodization, the electrolyte solution was constantly stirred with magnetic agitation to reduce the thickness of the double layer at the metal-electrode interface to obtain uniform local current densities on the titanium electrode (Mor and Varghese 2003). After anodization, the specimens were again sonicated with acetone, 70% ethanol and ddH2O, for 30 minutes each. These samples were termed ‘anodized nanotubular titanium’ since, as will be shown, titanium anodized in this manner possesses nanotubes penetrating the titanium surfaces.


Greater osteoblast proliferation on anodized nanotubular titanium upon electrical stimulation.

Ercan B, Webster TJ - Int J Nanomedicine (2008)

Schematic of the anodization system.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2636582&req=5

f1-ijn-3-477: Schematic of the anodization system.
Mentions: Afterwards, the surface cleaned titanium samples were etched with a 1.5% HF/1.5% HNO3 solution (Mallinckrodt Chemicals) for 5 minutes to remove the oxide layer. This was followed by an anodization process (Figure 1). For anodization, titanium samples were connected to a DC-powered electrochemical cell which had a two electrode configuration. A platinum mesh was used as the cathode and a titanium specimen was used as the anode. These platinum and titanium samples were connected to a DC power supply (3645A DC power supply, Circuit Specialists, Inc.) through copper wires. A constant voltage of 20 V was applied for 10 minutes according to previous studies (Yao et al 2005). The distance between the titanium anode and platinum cathode was kept constant at 1 cm. The electrolyte solution used in this study was 1.5% hydrofluoric acid and the anodization was conducted inside a Teflon beaker. During anodization, the electrolyte solution was constantly stirred with magnetic agitation to reduce the thickness of the double layer at the metal-electrode interface to obtain uniform local current densities on the titanium electrode (Mor and Varghese 2003). After anodization, the specimens were again sonicated with acetone, 70% ethanol and ddH2O, for 30 minutes each. These samples were termed ‘anodized nanotubular titanium’ since, as will be shown, titanium anodized in this manner possesses nanotubes penetrating the titanium surfaces.

Bottom Line: Currently used orthopedic implants composed of titanium have a limited functional lifetime of only 10-15 years.One of the reasons for this persistent problem is the poor prolonged ability of titanium to remain bonded to juxtaposed bone.It has been proposed to modify titanium through anodization to create a novel nanotubular topography in order to improve cytocompatibility properties necessary for the prolonged attachment of orthopedic implants to surrounding bone.

View Article: PubMed Central - PubMed

Affiliation: Division of Engineering, Brown University, Providence, RI 02912, USA.

ABSTRACT
Currently used orthopedic implants composed of titanium have a limited functional lifetime of only 10-15 years. One of the reasons for this persistent problem is the poor prolonged ability of titanium to remain bonded to juxtaposed bone. It has been proposed to modify titanium through anodization to create a novel nanotubular topography in order to improve cytocompatibility properties necessary for the prolonged attachment of orthopedic implants to surrounding bone. Additionally, electrical stimulation has been used in orthopedics to heal bone non-unions and fractures in anatomically difficult to operate sites (such as the spine). In this study, these two approaches were combined as the efficacy of electrical stimulation to promote osteoblast (bone forming cell) density on anodized titanium was investigated. To do this, osteoblast proliferation experiments lasting up to 5 days were conducted as cells were stimulated with constant bipolar pulses at a frequency of 20 Hz and a pulse duration of 0.4 ms each day for 1 hour. The stimulation voltages were 1 V, 5 V, 10 V, and 15 V. Results showed for the first time that under electrical stimulation, osteoblast proliferation on anodized titanium was enhanced at lower voltages compared to what was observed on conventional (nonanodized) titanium. In addition, compared to nonstimulated conventional titanium, osteoblast proliferation was enhanced 72% after 5 days of culture on anodized nanotubular titanium at 15 V of electrical stimulation. Thus, results of this study suggest that coupling the positive influences of electrical stimulation and nanotubular features on anodized titanium may improve osteoblast responses necessary for enhanced orthopedic implant efficacy.

Show MeSH
Related in: MedlinePlus