The researchers synthesized TiO2 nanotubes (NTs) on Ti foil through anodic oxidation at varying voltages. Pt nanoparticles were deposited on the NTs using two methods, but only one electrode showed reactivity to H2O2. Higher anodization voltages increased NT size but decreased stability, and only undamaged NTs successfully deposited Pt. The electrode with some carbon deposits on the NT surface detected H2O2 at -0.277V, indicating it may be suitable for a lactate biosensor.

1. Synthesis of TiO2 NT’s started with mechanical polishing
and sonication of Ti foil. The foils were dipped in acid (10%
HF, 42% HNO3, 48% H2O) to remove the oxidative layer
and any final contaminants. The NT’s were etched into the
foil by anodic oxidation at a potential range of 20V-35V for
30 min in an EG solution (97% vol. Ethylene Glycol, 3%
vol. Water, 1% wt. NH4F). The NTs were then annealed for
2 hours at 400⁰C to convert all tubes to the anatase
crystalline phase. Potential ranges and cleaning methods
were adjusted to develop ideal foils.
Method A: Pt NPs were deposited onto acceptable TiO2
NT foils via cyclic voltammetry (CV) in a solution of 1mM
H2PtCl6. 3 scans were performed with a potential range of
-0.4V to 0.5V using a scan rate of 10mV/s.
Method B: Process used same conditions as Method A,
except the solution was brought to 0.5M sulfuric acid.
Abstract
Implantable biosensors are an underdeveloped area of research
which could provide many benefits to tumor detection. Utilizing an
electrode that is selective toward the byproduct hydrogen peroxide
(H2O2) of many oxidase reactions enables a biosensor to be created
through the coupling of an enzyme layer. A biocompatible electrode
with reactivity towards H2O2 is developed using platinum (Pt)
nanoparticles (NPs) deposited on a titanium dioxide nanotube (TiO2
NT) array. TiO2 NTs were formed using anodic oxidation at varying
potentials in an ethylene glycol based solution. Pt was deposited onto
nanotube arrays of varying morphologies using cyclic voltammetry.
Two electrodes with slight carbon deposits on the nanotube surface
showed reactivity with H2O2 at a potential of around –0.277V.
Introduction
• Glioblastoma Multiforme (GBM) is a common type of malignant,
fast growing brain tumor with a 14.7 month average survival rate.
The key to increasing survival rate is early detection.1
• In-vivo amperometric biosensors are advantageous because they
detect biomarkers of GBM, such as increased lactic acid levels,
earlier than traditional detection methods (MRIs and CT scans).(2&4)
• An ideal in-vivo biosensor electrode should be selective, affordable,
and biocompatible. One possible design for a biosensor transducer
is an enzyme coupled electrode.4
• A lactate biosensor typically uses L-lactate oxidase as the enzyme.
When dissolved oxygen is present, L-lactate oxidase catalyzes the
reaction of lactate to pyruvate and hydrogen peroxide (H2O2).4
• H2O2 is electrochemically active and can be oxidized on the
electrode’s surface to give a current proportional to the lactate
concentration. A lactate biosensor electrode should, therefore, be
designed to be selective toward H2O2.4
• Titanium is a widely used metal in in-vivo medical applications due
to its high biocompatibility. It is also capable of forming nanotubes
via chemical oxidation.3
• Platinum has high catalytic activity toward H2O2, but a lower
biocompatibility than TiO2. Depositing Pt nanoparticles into the TiO2
NTs can increase H2O2 detection capability, while conserving the
biocompatibility of TiO2.3
1. American Brain Tumor Association. Glioblastoma and Malignant Astrocytoma (n.d.): n. pag. Web.
2. Nicolaidis, Stylianos, Biomarkers of glioblastoma multiforme, Metabolism - Clinical and Experimental,
Volume 64 , Issue 3 , S22 - S27.
3. Qing Kang, L. Y. (2008). An electro-catalytic biosensor fabricated with Pt-Au nanoparticle-decorated
titania nanotube array. Bioelectrochemistry, 84, 62-65.
4. Rassaei, Liza, Wouter Olthuis, and Seiya Tsujimura. "Lactate Biosensors: Current Status and Outlook."
Analytical and Bioanalytical Chemistry 406.1 (2014): 123-37. Springer Berlin Heidelberg. Web.
• Increasing anodization voltage increases NT size and
decreases NT stability.
• Pt NPs were not successfully deposited on severely
damaged NTs.
• Pt deposition under 0.5M sulfuric acid yielded more and
smaller NPs but did not result in H2O2 detection.
• Pt nanoparticles deposited on NT with some carbon
deposits showed detection of H2O2.
Electrode Development for a Lactate Biosensor
George Kuegler (CHE) and Gianna Terravecchia (CHE)
Advisor: Professor Susan Zhou (Chemical Engineering)
Electrode Development Results: Deposition & Reactivity
References
Conclusions
-1.6
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
-0.4 0 0.4
Current[mA]
Potential [V]
Titantium Foil
Reacts with H2O2
Does Not React with
H2O2
Method A Method B
Results: TiO2 Nanotubes
Several NTs displayed varying degrees and
combinations of morphologies that strayed
from ideally clean ordered tubes. The NTs
synthesized resulted in 4 types of
morphologies. A: Clean Uniform Tubes;
B: Cracking Between Tubes; C: Carbon
Deposits on Surface; D: Severe Pinching
25 30 35 40 45
30V
25V
20V
Anodization
Potential
Average NT Inner Diameter Range (nm)
-6.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
0 5 10 15 20
Current[mA]
Concentration H2O2 [mM]
Electrodes sensitive to H2O2 after Pt
deposition showed a detection peak similar to
the shape of the graph above.
CV graphs of Pt deposition were recorded.
The trend above emerged for predicting
electrode’s H2O2 detection capability.
H2O2 was dropped into a PBS buffer solution
to raise the H2O2 concentration by 5mM every
100 seconds.
The continuously measured current through
the Pt/TiO2NT electrode was linear with the
concentration of H2O2.
Adding acid in Method B resulted
in smaller NPs at a higher density
on the surface. Some particles
were small enough to fit in the
tubes. H2O2 detection, however,
was not observed.
Acceptable
67%
Fail
33%
20V
Acceptable
62%
Fail
38%
25V
Acceptable
50%
Fail
50%
30V
A B
DC
Method A shows a picture of the electrode morphology that successfully
detected H2O2, as shown in the figures above. Further investigation is
required to explain the cause of this observation.
A positive correlation was
observed between NT
stability and anodization
voltage.
-12.0
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
-0.4 0.1 0.6
Current[mA]
Potential [V]
PBS Only
10mM H2O2
-0.277V
-6.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
0 100 200 300 400 500
Current[mA]
Time [sec]