title: Chemostat-like microfluidic platform for highly sensitive detection of heavy metal ions using microbial biosensors.
abstract: Reporter-gene-based microbial biosensors have high potential for detecting small molecules, including heavy metal ions (HMIs), in a sensitive and selective manner by involving low costs. However, the sensitivity and dynamic range of the sensing mechanism are largely limited by the conventional culture environment that relies on the batch-type addition of the small molecules in nutrients and the subsequent genetic induction of sensing microbes. Here, we describe a high-throughput, chemostat-like microfluidic platform that can continuously supply both nutrients and inducers (HMIs) using microfabricated ratchet structures and a mixing microchannel network. We found that the microfluidic platform not only allowed microbial biosensors to be highly concentrated in a detection microchamber array but also enabled them to continuously grow and control synthetic genetic circuits in response to heavy metals. We also demonstrated that the combination of the platform and microbial biosensors enhanced the sensitivity for detecting divalent lead and cadmium ions by approximately three orders of magnitude relative to conventional batch-type methods. Because the platform is portable and only requires small sample volumes and fluorescent detection, the chemostat-like microfluidic platform in conjunction with microbial biosensors could be widely utilized to facilitate the specific and sensitive detection of molecular analytes on a chip.
authors.affiliation: Department of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulsan 689-798, Republic of Korea.
authors.forename: Minseok
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulsan 689-798, Republic of Korea.
authors.forename: Ji Won
authors.initials: JW
authors.lastname: Lim
authors.affiliation: Biosystems and Bioengineering Program, University of Science and Technology, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea; Infection and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea.
authors.forename: Hyun Ju
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulsan 689-798, Republic of Korea.
authors.forename: Sung Kuk
authors.initials: SK
authors.lastname: Lee
authors.affiliation: Biosystems and Bioengineering Program, University of Science and Technology, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea; Infection and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea. Electronic address: leesj@kribb.re.kr.
authors.forename: Sang Jun
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulsan 689-798, Republic of Korea; Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulsan 689-798, Republic of Korea. Electronic address: tskim@unist.ac.kr.
authors.forename: Taesung
authors.initials: T
authors.lastname: Kim
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D017930:Genes, Reporter; D057166:High-Throughput Screening Assays / Q000295:instrumentation; D019216:Metals, Heavy / Q000032:analysis* / Q000378:metabolism; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*
chemical_list: D019216:Metals, Heavy
keywords: Chemostat; Gene expression; Heavy metal ions; Microbial biosensor; Microfluidic platform