title: Aptamer cocktails: enhancement of sensing signals compared to single use of aptamers for detection of bacteria.
abstract: Microbial cells have many binding moieties on their surface for binding to their specific bioreceptors. The whole-cell SELEX process enables the isolation of various aptamers that can bind to different components on the cell surface such as proteins, polysaccharides, or flagella with high affinity and specificity. Here, we examine the binding capacity of an aptamer mixture (aptamer cocktail) composed of various combinations of 3 different DNA aptamers isolated from Escherichia coli and compare it with one of the single aptamers using fluorescence-tagged aptamers. The aptamer mixtures showed higher fluorescence signal than did any single aptamer used, which suggests that use of aptamer mixtures can enhance the sensitivity of detection of microbial cells. To further evaluate this effect, the signal enhancement and improvement of sensitivity provided by combinatorial use of aptamers were examined in an electrochemical detection system. With regard to current decreases, the aptamer cocktail immobilized on gold electrodes performed better than a single aptamer immobilized on gold electrodes did. Consequently, the detection limit achieved using the aptamers individually was approximately 18 times that when the 3 aptamers were used in combination. These results support the use of aptamer cocktails for detection of complex targets such as E. coli with enhanced sensitivity.
authors.affiliation: Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul 136-701, Republic of Korea.
authors.forename: Yeon Seok
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul 136-701, Republic of Korea.
authors.forename: Jinyang
authors.initials: J
authors.lastname: Chung
authors.affiliation: Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul 136-701, Republic of Korea; Graduate School of Energy and Environmental System Engineering, University of Seoul, Seoul 130-743, Republic of Korea.
authors.forename: Min Young
authors.initials: MY
authors.lastname: Song
authors.affiliation: Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul 136-701, Republic of Korea.
authors.forename: Jongsoo
authors.initials: J
authors.lastname: Jurng
authors.affiliation: Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul 136-701, Republic of Korea. Electronic address: bchankim@kist.re.kr.
authors.forename: Byoung Chan
authors.initials: BC
authors.lastname: Kim
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D004926:Escherichia coli / Q000737:chemistry / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000175:diagnosis; D006801:Humans; D052156:SELEX Aptamer Technique / Q000379:methods; D012680:Sensitivity and Specificity
chemical_list: D052157:Aptamers, Nucleotide
keywords: Aptamer cocktails; Bacteria; Cell-SELEX; Detection; Signal enhancement