title: A nanocoaxial-based electrochemical sensor for the detection of cholera toxin.
abstract: Sensitive, real-time detection of biomarkers is of critical importance for rapid and accurate diagnosis of disease for point of care (POC) technologies. Current methods do not allow for POC applications due to several limitations, including sophisticated instrumentation, high reagent consumption, limited multiplexing capability, and cost. Here, we report a nanocoaxial-based electrochemical sensor for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV) or square wave voltametry (SWV). The device architecture is composed of vertically-oriented, nanoscale coaxial electrodes in array format (~10(6) coaxes per square millimeter). The coax cores and outer shields serve as integrated working and counter electrodes, respectively, exhibiting a nanoscale separation gap corresponding to ~100 nm. Proof-of-concept was demonstrated for the detection of cholera toxin (CT). The linear dynamic range of detection was 10 ng/ml-1 µg/ml, and the limit of detection (LOD) was found to be 2 ng/ml. This level of sensitivity is comparable to the standard optical ELISA used widely in clinical applications, which exhibited a linear dynamic range of 10 ng/ml-1 µg/ml and a LOD of 1 ng/ml. In addition to matching the detection profile of the standard ELISA, the nanocoaxial array provides a simple electrochemical readout and a miniaturized platform with multiplexing capabilities for the simultaneous detection of multiple biomarkers, giving the nanocoax a desirable advantage over the standard method towards POC applications.
authors.affiliation: Department of Biology, Boston College, Chestnut Hill, MA 02467, United States.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Archibald
authors.affiliation: Department of Physics, Boston College, Chestnut Hill, MA 02467, United States.
authors.forename: Binod
authors.initials: B
authors.lastname: Rizal
authors.affiliation: Department of Biology, Boston College, Chestnut Hill, MA 02467, United States.
authors.forename: Timothy
authors.initials: T
authors.lastname: Connolly
authors.affiliation: Department of Physics, Boston College, Chestnut Hill, MA 02467, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Burns
authors.affiliation: Department of Physics, Boston College, Chestnut Hill, MA 02467, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Naughton
authors.affiliation: Department of Biology, Boston College, Chestnut Hill, MA 02467, United States. Electronic address: chilest@bc.edu.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Chiles
mesh_terms: D002772:Cholera Toxin / Q000032:analysis*; D003217:Conductometry / Q000295:instrumentation*; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008839:Microelectrodes; D036103:Nanotechnology / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002772:Cholera Toxin
keywords: Cholera; DPV; ELISA; Electrochemistry; Nanocoax; Point-of-care