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New template-based self-propelled gold/nickel/polyaniline/platinum(Au/Ni/PANI/Pt) microtubular engines, functionalized with the ConcanavalinA (ConA) lectin bioreceptor, are shown to be extremely useful forthe rapid, real-time isolation of Escherichia coli(E. coli) bacteria from fuel-enhanced environmental,food, and clinical samples. These multifunctional microtube enginescombine the selective capture of E. coliwith theuptake of polymeric drug-carrier particles to provide an attractivemotion-based theranostics strategy. Triggered release of the capturedbacteria is demonstrated by movement through a low-pH glycine-baseddissociation solution. The smaller size of the new polymer-metal microenginesoffers convenient, direct, and label-free optical visualization ofthe captured bacteria and discrimination against nontarget cells. [ABSTRACT FROM AUTHOR]

The transport properties of single-strand DNA probe-modified self-propelling micromachines are exploited for “on-the-fly” hybridization and selective single-step isolation of target nucleic acids from “raw” microliter biological samples (serum, urine, crude E. colilysate, saliva). The rapid movement of the guided modified microrockets induces fluid convection, which enhances the hybridization efficiency, thus enabling the rapid and selective isolation of nucleic acid targets from untreated samples. The integration of these autonomous microrockets into a lab-on-chip device that provides both nucleic acid isolation and downstream analysis could thus be attractive for diverse applications. [ABSTRACT FROM AUTHOR]

An extremely sensitive procedure for the isolation and detection of DNA from bacterial cell cultures is described. Direct asymmetric PCR amplified products from E. colicultures are specifically detected, at a concentration level as low as 0.01 cfu mL−1(cfu, colony forming unit), using disposable magnetic DNA hybridization amperometric sensors with no need for culture preconcentration steps. [ABSTRACT FROM AUTHOR]

A novel electrochemical immunosensor using screen-printed carbon electrodes and functionalized magnetic particles was developed for the determination of cortisol. Anti-cortisol antibody was immobilized onto protein A-modified magnetic particles and a direct competitive immunoassay involving cortisol antigen labeled with alkaline phosphatase (AP) was employed. The resulting conjugate was trapped on the surface of the screen-printed electrode with a small magnet. Cortisol quantification was accomplished by using 1-naphthyl phosphate as AP substrate and differential pulse voltammetry for the detection of the formed 1-naphthol. The variables involved in the preparation of the immunosensor and in the electrochemical detection reaction were optimized. The calibration plot obtained for cortisol exhibited a linear range between 5.0 × 10−3and 150 ng mL−1(r= 0.993). The limit of detection was 3.5 pg mL−1, and the EC50was 0.19 ng mL−1. These results demonstrate the high sensitivity achieved with this immunosensor design which compares favourably with other previous reports. The immunosensor also exhibited a high selectivity with respect to other corticosteroid compounds closely related to cortisol. The usefulness of the immunosensor for the analysis of real samples was demonstrated by analyzing certified human sera containing cortisol at two different concentration levels. [ABSTRACT FROM AUTHOR]