Author: Chen, Xi
Title: Nanoporous membrane based biosensor for detection of bacteria using electrochemical impedance spectroscopy
Degree: M.Sc.
Year: 2010
Subject: Hong Kong Polytechnic University -- Dissertations
Bacteria -- Identification
Aluminum oxide
Membranes (Biology)
Impedance spectroscopy
Nanostructured materials
Department: Department of Health Technology and Informatics
Pages: xvi, 53 leaves : ill. ; 30 cm.
Language: English
Abstract: A novel nanoporous anodic alumina oxide (AAO) membrane based biosensor (pore size is 100nm) is designed and fabricated for the use of bacteria detection. Four target bacteria, E.coli O157:H7, Staphylococcus aureus, Salmonella and Vibrio parahaemolyticus are studied and analyzed the normalized impedance change (NIC) through electrochemical impedance spectroscopy (EIS) under the frequency of 100Hz and voltage of 50mV. Surface modification is done to link and immobilize the specific antibodies onto the AAO membrane, which can be verified by contact angle measurement. Response time of different bacteria is tested at a high concentration (10⁷ CFU/ml), making sure the testing time is long enough to complete the antibody-antigen binding in maximum, and as a result, the four target bacteria have a response time between 180 min to 210 min. Bacteria concentration is controlled between 10² CFU/ml to 10⁸ CFU/ml. NIC results show this novel biosensor does achieve a high sensitivity because even a NIC around 20% can be get individually by the four target bacteria at low concentration and a NIC as big as 40-50% at medium/high concentration. Cross tests are followed to see the specificity of this biosensor, only to find out a NIC as small as 8-12% for the four target bacteria. Thus, this nanoporous AAO membrane based biosensor is characterized with high sensitivity, good specificity, short detection time (compared with days to weeks by conventional methods), low cost and easy fabrication. It is supposed to be a promising biological/biomedical application in fields such as food/water safety and clinical bacteria detection.
Rights: All rights reserved
Access: restricted access

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