Rapid and Sensitive Detection of Nano-fluidically Trapped Protein Biomarkers
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Rapid and Sensitive Detection of Nano-fluidically Trapped Protein Biomarkers Nandhinee Radha Shanmugam1, Anjan Panneer Selvam1, Thomas W.Barrett2, Steve Kazmierczak3 and Shalini Prasad1 1 Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, U.S.A. 2 Department of Veterans Affairs, Oregon Health & Science University, Portland, OR, U.S.A. 3 Department of Pathology, Oregon Health & Science University, Portland, OR, U.S.A. ABSTRACT In this work, we demonstrate the label-free and ultrasensitive detection of troponin-T, cardiac biomarker using nanoporous membrane integrated on a microelectrode sensor platform. The nanoporous membrane allows for spatial confinement of the protein molecules. Antigen interaction with thiol immobilized antibody perturbs the electrical double layer. Charge perturbations are recorded as impedance change at low frequency using the principle of electrochemical impedance spectroscopy (EIS). The measured impedance change is used to quantitatively determine the concentration of troponin-T in tested sample. We have shown that sensitivity of sensor for troponin-T to be 1pg/mL. The accuracy and reliability of this sensor was tested by comparing the experimental troponin-T concentration values with a commercially available electrochemiluminescence assay measured with Roche Elecsys analyzer. Using this technique we were successful in detecting protein biomarkers in whole blood, human serum, and ionic buffers. This technology provides a robust analytical platform for rapid and sensitive detection of protein biomarkers, thus establishing this technology as an ideal candidate for biomarker screening in clinical settings. INTRODUCTION Over the past few decades, macromolecules such as proteins, enzymes, DNA and RNA have been investigated for early diagnosis of diseases. Studies have revealed that protein biomarkers have the huge potential to characterize biological conditions [1]. Traditional methods like ELISA, Western blot, etc. are widely used diagnostic tools for detection and quantification of protein biomarkers. However, limitations such as detection limits, complexity of immunoassays, use of labels, time intensity, and cost makes these methods unsuitable for pointof-care (PoC) diagnostic applications[2, 3]. Hence, developing a simple and powerful diagnostic tool with high sensitivity, accuracy, and precision is required to bring technology to the patient in the field or at the bedside. A biosensor is an analytical device that can translate interactions between macromolecules into a measurable signal. In recent years, sensor platforms using nanomaterials have received significant interest due to their high surface area to volume ratio that enhances the sensitivity of detection[4]. The use of biologically inspired materials or structures in a nanotechnology enabled biosensor design offers tailored size matching to specific biomarkers[5]. The proteins in the cytoplasm are present in a crowded environment at high concentrations. This
phenomenon is termed macromolecular crowd
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