HUMAN IN VIVO CHOLESTEROL ANALYSIS BY MICROELECTRODE
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Case Western Reserve University School of Graduate Studies / OhioLINK
2015
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ndltd-OhioLink-oai-etd.ohiolink.edu-case14327548882021-08-03T06:31:26Z HUMAN IN VIVO CHOLESTEROL ANALYSIS BY MICROELECTRODE Xiaochun, Yu Chemistry This dissertation explores the application of a chronocoulometric technique to probe cholesterol efflux from the plasma membrane of human mucosa cells, which is the first measurement of its kind and initial human data is provided by Susu Yuan's thesis (2011). A double potential pulse coulometric scheme for cholesterol sensing at the platinum and carbon disk microelectrodes was applied, which avoids amperometric measurements that requires reference to the solution baseline current and baseline shift upon repositioning the electrode to contact the cell plasma membrane. In the double potential pulse scheme, the first pulse was set at 600 mV (pulse 1) to oxidize the hydrogen peroxide at the electrode surface, and the second pulse (600 mV, pulse 2) measure the background charges. The difference charge (pulse 1-pulse 2) signal arose from gradual accumulation of hydrogen peroxide generated between the electrode surface and cell plasma membrane. An electrode modified with BSA (bovine serum albumin) in contact with the plasma membrane served as the control electrode in these experiments to get background charge due to oxidation of contaminant. With this specially designed control, hydrogen peroxide that accumulated before pulse 1 could be estimated by enzyme-modified electrodes. This coulometric scheme allowed monitoring of background drift in real-time and signal averaging with an electrode held in contact with the mucosa plasma membrane. Chapter 1 describes a general overview of the scope of this research and briefly explains previous work performed in our research group that used different sensing strategies to measure cholesterol efflux from the plasma membrane. In chapter 2, mucosa probes (10 µm Pt microelectrode) were fabricated and the microelectrode electrodes were covalently linked with cholesterol oxidase to allow detection of cholesterol efflux from mucosa membrane using a double potential step. Control electrodes with similar degree of platinum roughness as the mucosa probe electrodes were designed to estimate background charge. Enzyme-modified electrodes showed a larger response at living tissue than control electrodes (modified with BSA). This indicated cholesterol detection using the mucosa probe electrodes. Meanwhile, correlation of the positive different charge including H2O2 oxidation (pulse 1- pulse 2) and quiet time negative charge (independent of H2O2) of control and enzyme-modified electrode was compared. There is linear relation between positive difference charge and negative charge that passes during the quiet time, and enzyme modified electrodes response are always larger than control electrodes. These data are interpreted as evidence for cholesterol efflux detected. In chapter 3, carbon fiber microelectrodes containing electrochemically deposited platinum are introduced. These showed increased signal relative to the control electrodes (modified with BSA) indicating cholesterol efflux from mucosa surface cells. Carbon fiber microelectrodes containing electrochemically deposited platinum show greatly improved cholesterol response relative to bulk platinum electrodes. Chapter 4 presents an outline of future directions for cholesterol analysis by optimizing pulse times and exploring commercial Pt nano-array probes. 2015-09-04 English text Case Western Reserve University School of Graduate Studies / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=case1432754888 http://rave.ohiolink.edu/etdc/view?acc_num=case1432754888 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Chemistry |
| spellingShingle |
Chemistry Xiaochun, Yu HUMAN IN VIVO CHOLESTEROL ANALYSIS BY MICROELECTRODE |
| author |
Xiaochun, Yu |
| author_facet |
Xiaochun, Yu |
| author_sort |
Xiaochun, Yu |
| title |
HUMAN IN VIVO CHOLESTEROL ANALYSIS BY MICROELECTRODE |
| title_short |
HUMAN IN VIVO CHOLESTEROL ANALYSIS BY MICROELECTRODE |
| title_full |
HUMAN IN VIVO CHOLESTEROL ANALYSIS BY MICROELECTRODE |
| title_fullStr |
HUMAN IN VIVO CHOLESTEROL ANALYSIS BY MICROELECTRODE |
| title_full_unstemmed |
HUMAN IN VIVO CHOLESTEROL ANALYSIS BY MICROELECTRODE |
| title_sort |
human in vivo cholesterol analysis by microelectrode |
| publisher |
Case Western Reserve University School of Graduate Studies / OhioLINK |
| publishDate |
2015 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=case1432754888 |
| work_keys_str_mv |
AT xiaochunyu humaninvivocholesterolanalysisbymicroelectrode |
| _version_ |
1719438305767981056 |