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Fast Detection of 2,4,6-Trinitrotoluene (TNT) at ppt Level by a Laser-Induced Immunofluorometric Biosensor

Division 1.5 Protein Analysis, Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Strasse 11, 12489 Berlin, Germany
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Biosensors 2020, 10(8), 89; https://doi.org/10.3390/bios10080089
Received: 26 June 2020 / Revised: 27 July 2020 / Accepted: 30 July 2020 / Published: 5 August 2020
(This article belongs to the Section Biosensor and Bioelectronic Devices)
The illegal use of explosives by terrorists and other criminals is an increasing issue in public spaces, such as airports, railway stations, highways, sports venues, theaters, and other large buildings. Security in these environments can be achieved by different means, including the installation of scanners and other analytical devices to detect ultra-small traces of explosives in a very short time-frame to be able to take action as early as possible to prevent the detonation of such devices. Unfortunately, an ideal explosive detection system still does not exist, which means that a compromise is needed in practice. Most detection devices lack the extreme analytical sensitivity, which is nevertheless necessary due to the low vapor pressure of nearly all explosives. In addition, the rate of false positives needs to be virtually zero, which is also very difficult to achieve. Here we present an immunosensor system based on kinetic competition, which is known to be very fast and may even overcome affinity limitation, which impairs the performance of many traditional competitive assays. This immunosensor consists of a monolithic glass column with a vast excess of immobilized hapten, which traps the fluorescently labeled antibody as long as no explosive is present. In the case of the explosive 2,4,6-trinitrotoluene (TNT), some binding sites of the antibody will be blocked, which leads to an immediate breakthrough of the labeled protein, detectable by highly sensitive laser-induced fluorescence with the help of a Peltier-cooled complementary metal-oxide-semiconductor (CMOS) camera. Liquid handling is performed with high-precision syringe pumps and chip-based mixing-devices and flow-cells. The system achieved limits of detection of 1 pM (1 ppt) of the fluorescent label and around 100 pM (20 ppt) of TNT. The total assay time is less than 8 min. A cross-reactivity test with 5000 pM solutions showed no signal by pentaerythritol tetranitrate (PETN), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). This immunosensor belongs to the most sensitive and fastest detectors for TNT with no significant cross-reactivity by non-related compounds. The consumption of the labeled antibody is surprisingly low: 1 mg of the reagent would be sufficient for more than one year of continuous biosensor operation. View Full-Text
Keywords: aviation security; biosensor; flow injection assay; monoclonal antibody; fluorescence microscope; lab-on-a-chip; microfluidic systems; antibody labeling; CMOS; diode laser; monolithic column; laser-induced fluorescence detector (LIF); additive manufacturing; low-cost; high-speed; non-competitive immunoassay; immunometric assay aviation security; biosensor; flow injection assay; monoclonal antibody; fluorescence microscope; lab-on-a-chip; microfluidic systems; antibody labeling; CMOS; diode laser; monolithic column; laser-induced fluorescence detector (LIF); additive manufacturing; low-cost; high-speed; non-competitive immunoassay; immunometric assay
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MDPI and ACS Style

Paul, M.; Tscheuschner, G.; Herrmann, S.; Weller, M.G. Fast Detection of 2,4,6-Trinitrotoluene (TNT) at ppt Level by a Laser-Induced Immunofluorometric Biosensor. Biosensors 2020, 10, 89. https://doi.org/10.3390/bios10080089

AMA Style

Paul M, Tscheuschner G, Herrmann S, Weller MG. Fast Detection of 2,4,6-Trinitrotoluene (TNT) at ppt Level by a Laser-Induced Immunofluorometric Biosensor. Biosensors. 2020; 10(8):89. https://doi.org/10.3390/bios10080089

Chicago/Turabian Style

Paul, Martin, Georg Tscheuschner, Stefan Herrmann, and Michael G. Weller 2020. "Fast Detection of 2,4,6-Trinitrotoluene (TNT) at ppt Level by a Laser-Induced Immunofluorometric Biosensor" Biosensors 10, no. 8: 89. https://doi.org/10.3390/bios10080089

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