Microfluidic three-dimensional hydrodynamic flow focusing for the rapid protein concentration analysis |
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| Authors: | Sungmin Hong Pei-Hsiang Tsou Chao-Kai Chou Hirohito Yamaguchi Chin B Su Mien-Chie Hung Jun Kameoka |
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| Institution: | 1.Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas 77843, USA;2.Department of Molecular and Cellular Oncology, University of Texas, M.D.Anderson Cancer Center, Houston, Texas 77030, USA;3.Center for Molecular Medicine and Graduate Institute of Cancer Biology, China Medical University, Taichung, Taiwan |
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| Abstract: | A simple microfluidic 3D hydrodynamic flow focusing device has been developed and demonstrated quantitative determinations of quantum dot 525 with antibody (QD525-antibody) and hemagglutinin epitope tagged MAX (HA-MAX) protein concentrations. This device had a step depth cross junction structure at a hydrodynamic flow focusing point at which the analyte stream was flowed into a main detection channel and pinched not only horizontally but also vertically by two sheath streams. As a result, a triangular cross-sectional flow profile of the analyte stream was formed and the laser was focused on the top of the triangular shaped analyte stream. Since the detection volume was smaller than the radius of laser spot, a photon burst histogram showed Gaussian distribution, which was necessary for the quantitative analysis of protein concentration. By using this approach, a linear concentration curve of QD525-antibody down to 10 pM was demonstrated. In addition, the concentration of HA-MAX protein in HEK293 cell lysate was determined as 0.283 ± 0.015 nM. This approach requires for only 1 min determining protein concentration. As the best of our knowledge, this is the first time to determinate protein concentration by using single molecule detection techniques. |
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