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Carbon Nanotubes as BiosensorsCarbon Nanotubes as Biosensors
ME 695Yang Yang
11/30/2004
OutlinesOutlines
IntroductionAmperometric biosensorsCarbon nanotube-modified
amperometric biosensorsConclusionReferences
IntroductionIntroduction
Materials for Biosensors 1. inert metals( Pt. Gold)
2. carbonaceous materials( graphite, carbon fibers, glassy carbon and carbon nanotubes)
IntroductionIntroduction
Carbon Nanotubes Fabrication- catalytic chemical vapor
deposition (CVD) method
IntroductionIntroduction
Types of Carbon Nanotubes1. Armchair (n, n)- all metallic2. Zig-zag(n, 0)-1/3 metallic(n=3k); 2/3 semi-conducting (remainder)3. Chiral(n, m)-1/3 metallic(n-m=3k); 2/3 semi-conducting (remainder)Single-walled: dia. 0.4 nm-2.0 nmMulti-walled: dia. 4.0 nm-50.0 nm
Amperometric biosensorsAmperometric biosensors
Biosensors: 1. converts a biological response into an electrical signal; 2. for determine the concentration of substances and other biological parameters.
Amperometric biosensorsAmperometric biosensors
a: biocatalystb: transducer—calorimetric, potentiometric, amperometric, pizeo-electricc: amplifierd: integrated circuite: display
Amperometric biosensorAmperometric biosensor
Carbon nanotube-modified Carbon nanotube-modified amperometric biosensorsamperometric biosensors
Preparation of carbon-nanotube electrode with Pt nanoparticles
1.Grow CNT directly from graphite substrate to form CNT electrode;2.Purify CNT electrode;3.Pt nanoparticles are dispersed on CNT electrode by potential step deposition to obtain Pt/CNT electrode;4. Immobilize GOD onto Pt/CNT electrode to obtain GOD/Pt/CNT electrode by bathing Pt/CNT in enzymatic solution for 12 hr;5. GOD/Pt/CNT electrode immersed in Nafion solution to prevent falling off;
Carbon nanotube-modified Carbon nanotube-modified amperometric biosensorsamperometric biosensors
Current response to successive injection of 0.1 mM hydrogen peroxide
1-5: CNT electrodes;
6: Graphite electrodes
CNT electrodes more electrocatalytic active than Graphite electrodes
*K
Carbon nanotube-modified Carbon nanotube-modified amperometric biosensorsamperometric biosensors
Current response to successive injection of 0.1 mM hydrogen peroxide
2(0.2V)-3(0.6): Pt/CNT electrodes;1(0.6V): Pt/Graphite electrodes Response behavior of Pt/CNT at 0.6 VMuch better than Pt/Graphite
Comparing curve 3 in (b) and curve 1 in (a), Pt nanoparticles greatly improves the
electrocatalytic activity.
Carbon nanotube-modified Carbon nanotube-modified amperometric biosensorsamperometric biosensors
Current response to successive injection of 0.1 mMglucose
Curve 1: Nafion/GOD/CNT
Curve 2: Nafion/GOD/Pt/CNT
Potential 0.6 V
Pt/CNT composite better for immobilization of GOD than CNT/Graphite
Carbon nanotube-modified Carbon nanotube-modified amperometric biosensorsamperometric biosensors
Another method of preparing CNT-based Glucose electrode
1. Wash MWCNT, polish the surface of basal plane pyrolytic graphite(bppg) electrode;
2. Rubbing electrode with filter paper containing 2 mg MWCNT for 1 min.
3. Mixing 50 miuL sol-gel composite solution with 50 miuL glucose oxidase solution then dope 20 miuL on modified MWCNT bppg electrode
4. Dry in air flow.
Carbon nanotube-modified amperometric biosensorsCarbon nanotube-modified amperometric biosensors
Current responseTo successive Addition of 0.5 mMGlucose.Curve A: bare bppg/biocompositeCurve B: bppg/CNT/biocomposite
Inset: slope 200nA/mMDetection limit: 50 miuMLinear range: 0.2-20mM(human 4.4-6.6 mM
ConclusionsConclusions Materials for biosensors manufacturing Concepts of biosensor and amperometric
biosensor Comparison of current response between
conventional biosensors and CNTs-modified shows CNT biosensors respond rapidly and actively
CNTs are promising materials for fabrication of novel biosensors.
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