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생체분자의 검출 연구
“Electrochemical microgap immunosensors for selective detection of pathogenic Aspergillus niger”
Journal of Hazardous Materials 411 (2021) 125069
Aspergillus niger (A. niger) is a well-known allergenic, harmful fungus in the indoor environment that can cause asthmatic symptoms and atopy. Previous immunosensing approach suffers from an insufficient detection limit, mainly because there are no techniques for target amplification. We report an electrochemical immunosensor that selectively quantifies the A. niger based on the detection of extracellular proteins by using a specific interaction with antibody. The sensor was designed to show a decrease in redox current upon binding of the antigens secreted from A. niger onto an antibody-immobilized surface between the interdigitated electrodes. The extracellular proteins were profiled by LC-MS/MS to identify the antigens existing in the A. niger solution. Since the targets of the sensor are the proteins, its sensitivity and selectivity remain almost intact even after filtration of the spores. It was also found that the use of secretion promoter in the sampling stage greatly improved the sensor’s limit of detection (LOD) for the spores. By this, the LOD was lowered by a few orders of magnitude so as to reach the value as low as ~101 spores/mL.
“Calibration curve-free electrochemical quantitation by micro-nano multi-scale gap devices”
Microchimica Acta, 188, 200 (2021)
Quantitation without relying on the calibration curve has long been an issue of overcoming analytical problems accompanied with the inherent limitations of the calibration curve fitting errors. Here, we report on a calibration curve-free method for electrochemical quantitation based on a multi-scale gap device (MGD). The MGD is an integrated device having a series of interdigitated electrodes (IDE) with micro-to-nano gap distances. The device shows a gap-dependent redox current of the analyte when subjected to the electrochemical cycling between the two facing electrodes of its componential IDEs. Based on the fact that the current increases as the gap distance decreases, the analyte concentration could be directly estimated: the rate of increase in the current was directly proportional to the analyte concentration. The calibration curve was not necessary for the quantitation. The accuracy of this MGD approach was better than that of an IDE collection of the same gap distance, which was deteriorated at the larger gap distances particularly. The MGD-based quantitation of dopamine, potassium ferricyanide, and aminophenol was demonstrated in a relatively broad range of concentrations (100 nM–5 mM).
“Quantification of antigen by digital domain analysis of integrated nanogap biosensors”
Biosensors and Bioelectronics 97 (2017) 273–277
Nanogap biosensor shows a distinct conduction change upon sandwich-type immobilization of gold nanoparticle probes onto the gap region in the presence of target biomolecules. Although this large conductance change could be advantageous in distinguishing signal on or off devices, since the extent of conductance change is quite irregular even at the same analyte concentrations, it fails to extract quantitative information from its level of conductance change. In other words, the conductance change of a single device does not reflect the concentration of the target molecule. In this study, we introduce an alternative approach of interpreting the concentration of target molecules using digital domain analysis of integrated nanogap devices, where the fraction of signal-on-devices, or on-device-percentage (ODP), was translated into the concentration of the target molecule. The ODP was found to be closely related to the number density of the immobilized probes and, therefore, to be an excellent measure of the analyte concentration, which was demonstrated in the immuno-selective detection and quantification of influenza A hemagglutinin and prostate specific antigen.