AC electrothermal enhancement of heterogeneous assays in microfluidics.

AC-driven electrothermal flow is used to enhance the temporal performance of heterogeneous immuno-sensors in microfluidic systems by nearly an order of magnitude. AC electrokinetic forces are used to generate electrothermal flow, which in turn produces a circular stirring fluid motion that enhances the transport of diffusion-limited proteins. This provides more binding opportunities between suspended antigens and wall-immobilized antibodies. We investigate experimentally the effectiveness of electrothermal stirring, using a biotin-streptavidin heterogeneous assay, in which biotin is immobilized, and fluorescently-labeled streptavidin is suspended in a high conductivity buffer (sigma = 1.0 S m(-1)). Microfabricated electrodes were integrated within a microwell and driven at a frequency of f= 200 kHz and 10 V(rms). Fluorescent intensity measurements show that for a five minute assay, electrothermal stirring increases the binding rate by a factor of almost nine. Similar binding improvement was measured for longer assays, up to fifteen minutes. The electrothermal enhancement of this assay was modeled numerically and agrees with experimental binding rates. The measured fluid velocity of 22 +/- 2 microm s(-1) was significantly lower than that predicted by the numerical model, 1.1 mm s(-1), but nevertheless shows the same fourth power dependence on applied potential. The results demonstrate the ability for electrothermal stirring to reliably improve the response time and sensitivity within a given time limit for microfluidic diffusion-limited sensors.

[1]  H. A. Pohl,et al.  Dielectrophoresis: The Behavior of Neutral Matter in Nonuniform Electric Fields , 1978 .

[2]  E. Delamarche,et al.  Patterned delivery of immunoglobulins to surfaces using microfluidic networks. , 1997, Science.

[3]  Dimitra N. Stratis-Cullum,et al.  A miniature biochip system for detection of aerosolized Bacillus globigii spores. , 2003, Analytical chemistry.

[4]  M. Bazant,et al.  Breaking symmetries in induced-charge electro-osmosis and electrophoresis , 2005, Journal of Fluid Mechanics.

[5]  W. Deen.  Analysis Of Transport Phenomena , 1998 .

[6]  Samuel K Sia,et al.  An integrated approach to a portable and low-cost immunoassay for resource-poor settings. , 2004, Angewandte Chemie.

[7]  D. Beebe,et al.  A particle image velocimetry system for microfluidics , 1998 .

[8]  P. Englebienne,et al.  Surface plasmon resonance: principles, methods and applications in biomedical sciences , 2003 .

[9]  F. J. Wolf,et al.  THE PROPERTIES OF STREPTAVIDIN, A BIOTIN-BINDING PROTEIN PRODUCED BY STREPTOMYCETES. , 1964, Archives of biochemistry and biophysics.

[10]  大房 健.  基礎講座 電気泳動(Electrophoresis) , 2005 .

[11]  M. R. Bown,et al.  AC electroosmotic flow in a DNA concentrator , 2006 .

[12]  H. Morgan,et al.  Ac electrokinetics: a review of forces in microelectrode structures , 1998 .

[13]  H. Nygren,et al.  Kinetics of antigen-antibody reactions at solid-liquid interfaces. , 1988, Journal of immunological methods.

[14]  S. Wereley,et al.  PIV measurements of a microchannel flow , 1999 .

[15]  L M Tender,et al.  Array biosensor for simultaneous identification of bacterial, viral, and protein analytes. , 1999, Analytical chemistry.

[16]  K. Kaler,et al.  A novel dielectrophoresis-based device for the selective retention of viable cells in cell culture media. , 1997, Biotechnology and bioengineering.

[17]  S. D. Smith,et al.  Spectroscopy … , 2020, Nature.

[18]  A. Ajdari,et al.  Pumping liquids using asymmetric electrode arrays , 2000, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[19]  J. El-Ali,et al.  Removal of PCR inhibitors using dielectrophoresis as a selective filter in a microsystem. , 2003, Lab on a chip.

[20]  W. M. Haynes.  CRC Handbook of Chemistry and Physics , 1990 .

[21]  A. Majumdar,et al.  Diffusion-limited patterning of molecules in nanofluidic channels. , 2006, Nano letters.

[22]  M. Wilchek,et al.  Application of avidin-biotin technology to affinity-based separations. , 1990, Journal of chromatography.

[23]  D G Myszka,et al.  Extending the range of rate constants available from BIACORE: interpreting mass transport-influenced binding data. , 1998, Biophysical journal.

[24]  E E Swartzman,et al.  A homogeneous and multiplexed immunoassay for high-throughput screening using fluorometric microvolume assay technology. , 1999, Analytical biochemistry.

[25]  P. Wong,et al.  Electrokinetics in micro devices for biotechnology applications , 2004, IEEE/ASME Transactions on Mechatronics.

[26]  J. Rossier,et al.  Enzyme linked immunosorbent assay on a microchip with electrochemical detection. , 2001, Lab on a chip.

[27]  Paul H. Bessette,et al.  Marker-specific sorting of rare cells using dielectrophoresis. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[28]  R. C. Weast.  CRC Handbook of Chemistry and Physics , 1973 .

[29]  Dazhi Wang,et al.  Electrothermal stirring for heterogeneous immunoassays. , 2005, Lab on a chip.

[30]  M. Bazant,et al.  Induced-charge electro-osmosis , 2003, Journal of Fluid Mechanics.

[31]  P. Gascoyne,et al.  Particle separation by dielectrophoresis , 2002, Electrophoresis.

[32]  宁北芳,et al.  疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A , 2005 .

[33]  David Juncker,et al.  Simultaneous detection of C-reactive protein and other cardiac markers in human plasma using micromosaic immunoassays and self-regulating microfluidic networks. , 2004, Biosensors & bioelectronics.

[34]  Arun Majumdar,et al.  Effects of biological reactions and modifications on conductance of nanofluidic channels. , 2005, Nano letters.

[35]  Xingyu Jiang,et al.  A miniaturized, parallel, serially diluted immunoassay for analyzing multiple antigens. , 2003, Journal of the American Chemical Society.

[36]  Guoqing Hu,et al.  An Electrokinetically-Controlled Immunoassay for Simultaneous Detection of Multiple Microbial Antigens , 2005, Biomedical microdevices.

[37]  I. Bizjak,et al.  Measurement of the wrong-sign decays D0 --> K+ pi- pi0 and D0 --> K+ pi- pi+ pi-, and search for CP violation. , 2005, Physical review letters.