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A Combined Experimental and Theoretical Study on the Immunoassay of Human Immunoglobulin Using a Quartz Crystal Microbalance
Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan
* Author to whom correspondence should be addressed.
Received: 3 November 2010; in revised form: 29 November 2010 / Accepted: 6 December 2010 / Published: 15 December 2010
Abstract: We investigate a immunoassay biosensor that employs a Quartz Crystal Microbalance (QCM) to detect the specific binding reaction of the (Human IgG1)-(Anti-Human IgG1) protein pair under physiological conditions. In addition to experiments, a three dimensional time domain finite element method (FEM) was used to perform simulations for the biomolecular binding reaction in microfluidic channels. In particular, we discuss the unsteady convective diffusion in the transportation tube, which conveys the buffer solution containing the analyte molecules into the micro-channel where the QCM sensor lies. It is found that the distribution of the analyte concentration in the tube is strongly affected by the flow field, yielding large discrepancies between the simulations and experimental results. Our analysis shows that the conventional assumption of the analyte concentration in the inlet of the micro-channel being uniform and constant in time is inadequate. In addition, we also show that the commonly used procedure in kinetic analysis for estimating binding rate constants from the experimental data would underestimate these rate constants due to neglected diffusion processes from the inlet to the reaction surface. A calibration procedure is proposed to supplement the basic kinetic analysis, thus yielding better consistency with experiments.
Keywords: biosensor; Quartz Crystal Microbalance; Finite Element Method (FEM); basic kinetic analysis; human IgG1
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Liao, P.-J.; Chang, J.-S.; Chao, S.D.; Chang, H.-C.; Huang, K.-R.; Wu, K.-C.; Wung, T.-S. A Combined Experimental and Theoretical Study on the Immunoassay of Human Immunoglobulin Using a Quartz Crystal Microbalance. Sensors 2010, 10, 11498-11511.
Liao P-J, Chang J-S, Chao SD, Chang H-C, Huang K-R, Wu K-C, Wung T-S. A Combined Experimental and Theoretical Study on the Immunoassay of Human Immunoglobulin Using a Quartz Crystal Microbalance. Sensors. 2010; 10(12):11498-11511.
Liao, Po-Jen; Chang, Jeng-Shian; Chao, Sheng D.; Chang, Hung-Chi; Huang, Kuan-Rong; Wu, Kuang-Chong; Wung, Tzong-Shyan. 2010. "A Combined Experimental and Theoretical Study on the Immunoassay of Human Immunoglobulin Using a Quartz Crystal Microbalance." Sensors 10, no. 12: 11498-11511.