title: A nanoporous membrane-based impedimetric immunosensor for label-free detection of pathogenic bacteria in whole milk.
abstract: We introduce a nanoporous membrane based impedimetric immunosensor for the label-free detection of bacterial pathogens in whole milk. A simple and rapid method to modify a commercially available alumina nanoporous membrane with hyaluronic acid (HA) effectively reduced the non-specific binding of biomolecules and other cells, and permitted successful immobilization of antibodies. Escherichia coli O157:H7, one of the most harmful food-borne pathogenic bacteria, was tested as a model pathogen in this study. The ionic impedance of electrolytes through nanopores, due to antibody-pathogen interactions, was monitored by impedance spectra and analyzed by normalized impedance change (NIC). The regression equation for the NIC at 1 kHz versus concentration of E. coli O157:H7 (10-10(5)cfu/ml) was obtained, and the detection limit found to be as low as 10 cfu/ml. In addition, the proposed immunosensor was successfully used for the detection of E. coli O157:H7 in whole milk samples with the detection limit as low as 83.7 cfu/ml with 95% probability. The specificity of the immunosensor was also demonstrated using non-target bacteria, including Staphylococcus aureus, Bacillus cereus, and non pathogenic E. coli DH5α. This study shows that a HA-functionalized nanoporous membrane-based impedimetric sensor is capable of detecting pathogenic bacteria in whole milk without any pretreatment. This is a significant step for evaluating the safety of food and environmental samples and other medical diagnostics.
authors: Institute of Life Sciences and Resources & Department of Food Science and Biotechnology, College of Life Sciences, Kyung Hee University, Yongin, Republic of Korea.
authors: Cho-Kyung
authors: CK
authors: Joung
authors: Han-Nah
authors: HN
authors: Kim
authors: Min-Cheol
authors: MC
authors: Lim
authors: Tae-Joon
authors: TJ
authors: Jeon
authors: Hae-Yeong
authors: HY
authors: Kim
authors: Young-Rok
authors: YR
authors: Kim
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D000818:Animals; D055910:Antibodies, Immobilized / Q000737:chemistry; D001409:Bacillus cereus / Q000302:isolation & purification; D017097:Electric Impedance; D004867:Equipment Design; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005516:Food Microbiology; D006820:Hyaluronic Acid / Q000737:chemistry; D007118:Immunoassay / Q000191:economics / Q000295:instrumentation*; D057230:Limit of Detection; D008567:Membranes, Artificial; D008892:Milk / Q000382:microbiology*; D016062:Porosity; D013211:Staphylococcus aureus / Q000302:isolation & purification
chemical_list: D055910:Antibodies, Immobilized; D008567:Membranes, Artificial; D006820:Hyaluronic Acid; D000537:Aluminum Oxide