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Development and Characterization of an Iridium-Modified Electrochemical Biosensor for Potential Diabetic Patient Management

Fang, Lei
http://rave.ohiolink.edu/etdc/view?acc_num=case1223049333

Abstract Details

2009, Doctor of Philosophy, Case Western Reserve University, Chemical Engineering.
The goal of this research was to apply thick-film screen printing technology to produce a single-use, disposable, cost-effective electrochemical biosensor prototype in large scale. Iridium nanoparticles supported by carbon were selected to modify the electrode of the biosensor for its excellent catalytic effect towards the commonly detected electrochemical active species, i.e., hydrogen peroxide, nicotinamide adenine dinucleotide (reduced form, NADH), and nicotinamide adenine dinucleotide (oxidized form, NAD+). The development of this electrochemical biosensor prototype can establish a platform technology for various analytes of clinical importance. This study focused on the biosensing of the following analytes related to diabetes, i.e., 3-hydroxybutyrate (3HB), fructosyl valine, and the HbA1c, providing an analytical tool for diabetic patient management. The first part of this study discusses the importance of developing a point-of-care amperometric biosensor to detect 3-hydroxybutyrate (3HB) for diabetic patient management. Current electrochemical detection methods for 3HB require at least two stepwise reactions or a mediator. The detection method in this study only requires a single reaction step without any mediator, which can potentially also be more accurate, sensitive, cost-effective and stable over the long term. In this detection method, the enzyme D-3-hydroxybutyrate dehydrogenase (3HBDH, EC 1.1.1.30) was immobilized on the iridium–modified sensor prototypes which detect the NADH produced by the reaction of 3HB with NAD+ in the presence of 3HBDH. This microelectrode quantified the NADH electrochemically, which produced an electrical current that would then be used to quantify the concentration of 3HB. The interferences from uric acid, NAD+, and serum were measured. It was concluded that the level of 3HB could still be quantified well in the presence of these interfering species. Spectrometric measurements of NADH and 3HB were performed in both PBS and bovine serum and correlated very well with the electrochemical measurements of 3HB, using our biosensor prototype. The relationship between the sensing performance of this 3HB biosensor and the element properties in fabrication and the characterization parameters were assessed. As a result, the value for the element properties in fabrication and the parameters in the characterization were determined based on the experimental results together with the requirements for practical applications. Finally, inkjet printing technology was applied for the enzyme ink deposition for the mass-production of this biosensor. The biosensors from inkjet printing were characterized in both PBS and bovine serum. In the next part of this study, this biosensor prototype was used for the detection of NAD+, in order to quantify the interference from AcAc on the 3HB detection, and to quantify numerous biomarkers related to NAD+. This biosensor operated in the reduction mode at a relatively low electrochemical potential (-0.4V vs Ag/AgCl reference electrode) in both buffer solution and bovine serum. The biosensor outputs showed high sensitivity, high linearity, and high reproducibility. The temperature effect and the interference from NADH were also assessed. As a separate study, the measurement of glycosylated hemoglobin (HbA1c) was considered to be most important for the long-term management of diabetic patients. Electrochemical detection of HbA1c was proposed involving multi-step decomposition of HbA1c to small molecules proportional to the concentration of HbA1c, then detection of the produced molecules amperometricly. This biosensor prototype was used for the detection of both HbA1c, and fructosyl valine (FV), one of the produced small molecules as a model compound for the HbA1c detection. Consequently, electrochemical biosensors for the detection of FV and HbA1c were developed. Quantifications of FV and HbA1c were carried out at a relatively low electrochemical potential (+0.25V vs Ag/AgCl) at an ambient temperature to detect the enzymatically produced H2O2. The enzymes, e.g., fructosyl amine oxidase (E.C. 1.5.3.x, FAO) and the lysis buffer were then co-immobilized onto the iridium-modified disposable sensor for HbA1c detection in whole human blood. This reagent-free electrochemical biosensor detected HbA1c in the physiological range with practical sensitivity and good linearity. Finally, a diffusion-reaction model was developed for the electrochemical detection of 3HB in solution which achieved reasonable agreement with the experimental results.
Chung-Chiun Liu (Committee Chair)
Vernon Anderson (Committee Member)
Heidi Martin (Committee Member)
Harihara Baskaran (Committee Member)
171 p.
Biochemistry; Biomedical Research; Chemical Engineering; Engineering
Iridium-modified; Electrochemical biosensor; Think film printing; Diabetic patient management; Ketone body; 3-hydroxybutyrate(3HB); Nicotinamide adenine dinucleotide(NAD+); Glycosylated hemoglobin (HbA1c); Fructosyl valine; Diffusion-reaction model

Recommended Citations

Citations

  • Fang, L. (2009). Development and Characterization of an Iridium-Modified Electrochemical Biosensor for Potential Diabetic Patient Management [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1223049333

    APA Style (7th edition)

  • Fang, Lei. Development and Characterization of an Iridium-Modified Electrochemical Biosensor for Potential Diabetic Patient Management. 2009. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1223049333.

    MLA Style (8th edition)

  • Fang, Lei. "Development and Characterization of an Iridium-Modified Electrochemical Biosensor for Potential Diabetic Patient Management." Doctoral dissertation, Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1223049333

    Chicago Manual of Style (17th edition)

case1223049333
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© 2008, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.