Microfluidics and Nanofluidics

, Volume 8, Issue 6, pp 739–753 | Cite as

Magnetophoretic mixing for in situ immunochemical binding on magnetic beads in a microfluidic channel

  • Ranjan Ganguly
  • Thomas Hahn
  • Steffen HardtEmail author
Research Paper


Functionalized magnetic beads offer promising solutions to a host of micro-total analysis systems ranging from immunomagnetic biosensors to cell separators. Immunochemical binding of functional biochemical agents or target biomolecules serves as a key step in such applications. Here we show how magnetophoretic motion of magnetic microspheres in a microchannel is harnessed to promote in situ immunochemical binding of short DNA strands (probe oligonucleotide) on the bead surface via streptavidin–biotin bonds. Using a transverse magnetic field gradient, the particles are transported across a co-flowing analyte stream containing biotinylated probe oligonucleotides that are labeled with a Cy3-fluorophore. Quantification of the resulting biotin–streptavidin promoted binding has been achieved through fluorescence imaging of the magnetophoretically separated magnetic particles in a third stream of phosphate buffered saline. Both the experimental and numerical data indicate that for a given flow rate, the analyte binding per bead depends on the flow fraction of the co-flowing analyte stream through the microchannel, but not on the fluid viscosity. Parametric studies of the effects of fluid viscosity, analyte flow fraction, and total flow rate on the extent of binding and the overall analyte separation rate are also conducted numerically to identify favorable operating regimes of a flow-through immunomagnetic separator for biosensing, cell separation, or high-throughput applications.


Magnetic microspheres Microfluidics Micromixing Immunochemical Binding Lagrangian Particle Tracking 



Funding from the Alexander von Humboldt Stiftung, Germany, is gratefully acknowledged for providing the fellowship support to the fist author. T. Hahn acknowledges support by the German Research Foundation (DFG). The authors also acknowledge Tobias Baier (Center of Smart Interfaces, TU Darmstadt) for fruitful discussion on the scaling analysis.


  1. Baier T, Mohanty S, Drese KS, Rampf F, Kim J, Schönfeld F (2009) Modelling immunomagnetic cell capture in CFD. Microfluid Nanofluid 7:205–216CrossRefGoogle Scholar
  2. Biswal SL, Gast AP (2004) Micromixing with linked chains of paramagnetic particles. Anal Chem 76:6448–6455CrossRefGoogle Scholar
  3. Branca C, Magazu S, Maisano G, Migliardo F, Romeo G (2002) Hydration study of PEG/water mixture by quasi elastic light scattering, acoustic and rheological measurements. J Phys Chem B 106:10272–10276CrossRefGoogle Scholar
  4. Crowe CT (2006) Multiphase flow handbook. Taylor and Francis, Boca Raton, FLzbMATHGoogle Scholar
  5. Ganguly R, Puri IK (2007) Field-assisted self-assembly of superparamagnetic nanoparticles for biomedical, MEMS and BioMEMS applications. Adv Appl Mech 41:293–335CrossRefGoogle Scholar
  6. Graham DL, Ferreira HA, Freitas PP (2004) Magnetoresistive-based biosensors and biochips. Trends Biotechnol 22:455–462CrossRefGoogle Scholar
  7. Greenwood PA, Greenway GM (2002) Sample manipulation in micro total analytical systems. Trends Anal Chem 21:726–740CrossRefGoogle Scholar
  8. Hardt S, Pennemann H, Schönfeld F (2006) Theoretical and experimental characterization of a low-Reynolds number split-and-recombine mixer. Microfluid Nanofluid 2:237–248CrossRefGoogle Scholar
  9. Hayes MA, Polson NA, Phayre AN, Garcia AA (2001) Flow-based microimmunoassay. Anal Chem 73:5896–5902CrossRefGoogle Scholar
  10. Huang S-C, Stump MD, Weiss R, Caldwell KD (1996) Binding of biotinylated DNA to streptavidin-coated polystyrene latex: effect of chain length and particle size. Anal Biochem 237:115–122CrossRefGoogle Scholar
  11. Ichikawa N, Hosokawa K, Maeda R (2004) Interface motion of capillary-driven flow in rectangular microchannel. J Colloid Interf Sci 280:155–164CrossRefGoogle Scholar
  12. Jiang F, Drese KS, Hardt S, Küpper M, Schönfeld F (2004) Helical flows and chaotic mixing in curved micro channels. AIChE J 50:2297–2305CrossRefGoogle Scholar
  13. Kang Y, Cetin B, Wu Z, Li D (2009) Continuous particle separation with localized AC-dielectrophoresis using embedded electrodes and an insulating hurdle. Electrochimia Acta 54:1715–1720CrossRefGoogle Scholar
  14. Kang Y, Li D, Kalams SA, Eid JE (2008) DC-dielectrophoretic separation of biological cells by size. Biomed Microdevices 10:243–249CrossRefGoogle Scholar
  15. Knight JB, Vishwanath A, Brody JP, Austin RH (1998) Hydrodynamic focusing on a silicon chip: mixing nanoliters in microseconds. Phys Rev Lett 80:3863–3866CrossRefGoogle Scholar
  16. Lacharme F, Vandevyver C, Gijs MAM (2008) Full on-chip nanoliter immunoassay by geometrical magnetic trapping of nanoparticle chains. Anal Chem 80:2905–2910CrossRefGoogle Scholar
  17. Lacharme F, Vandevyver C, Gijs MAM (2009) Magnetic beads retention device for sandwich immunoassay: comparison of off-chip and on-chip antibody incubation. Microfluid Nanofluid (Article in Press). doi: 10.1007/s10404-009-0424-7
  18. Lukacs GL, Haggie P, Seksek O, Lechardeur D, Freedman N, Verkman AS (2000) Size-dependent DNA mobility in cytoplasm and nucleus. J Biol Chem 275:1625–1629CrossRefGoogle Scholar
  19. Lund-Olesen T, Buus BB, Howalt JG, Hansen MF (2008) Magnetic bead micromixer: influence of magnetic element geometry and field amplitude. J Appl Phys 103:07E902(1–3)Google Scholar
  20. Manz A, Graber N, Widmer HM (1990) Miniaturized total chemical analysis systems: a novel concept for chemical sensing. Sens Actuators B Chem 1:244–248CrossRefGoogle Scholar
  21. Modak N, Datta A, Ganguly R (2009) Cell separation in a microfluidic channel using magnetic microspheres. Microfluid Nanofluid 6:647–660CrossRefGoogle Scholar
  22. Morton KJ, Loutherback K, Inglis DW, Tsui OK, Sturm JC, Choua SY, Austin RH (2008) Crossing microfluidic streamlines to lyse, label and wash cells. Lab Chip 8:1448–1453CrossRefGoogle Scholar
  23. Moser Y, Lehnert T, Gijs MAM (2009) Quadrupolar magnetic actuation of superparamagnetic particles for enhancedmicrofluidic perfusion. Appl Phys Lett 94:022505(1–3)Google Scholar
  24. Mullins JM (1999) Overview of fluorophores. In: Javois LC (ed) Immunocytochemical methods and protocols, 2nd edn. (Vol. 34 of Biomedical and life sciences). Humana Press, Totowa, NJ, pp 107–116Google Scholar
  25. Nandy K, Chaudhuri S, Ganguly R, Puri IK (2008) Analytical model for the magnetophoretic capture of magnetic microspheres in microfluidic devices. J Magn Magn Mater 320:1398–1405Google Scholar
  26. Nguyen N-T, Wu Z (2005) Micromixers—a review. J Micromech Microeng 15:R1–R16CrossRefGoogle Scholar
  27. Pamme N, Manz A (2004) On-chip free-flow magnetophoresis: continuous flow separation of magnetic particles and agglomerates. Anal Chem 76:7250–7256CrossRefGoogle Scholar
  28. Radbruch A, Mechtold B, Thiel A, Miltenyi S, Pfluger E (1994) High-gradient magnetic cell sorting. Methods Cell Biol 42:387–403CrossRefGoogle Scholar
  29. Rida A, Gijs MAM (2004) Manipulation of self-assembled structures of magnetic beads for microfluidic mixing and assaying. Anal Chem 76:6239–6246CrossRefGoogle Scholar
  30. Rong R, Choi J-W, Ahn CH (2006) An on-chip magnetic bead separator for bio-cell sorting. J Micromech Microeng 16:2783–2790CrossRefGoogle Scholar
  31. Roy T, Chakraborty S, Sinha A, Ganguly R, Puri IK (2009) Magnetic microsphere-based mixers for micro-droplets. Phys Fluids 21:027101(1–7)Google Scholar
  32. Sinha A, Ganguly R, De AK, Puri IK (2007) Single magnetic particle dynamics in a microchannel. Phys Fluids 19:117102(1–5)Google Scholar
  33. Sinha A, Ganguly R, Puri IK (2009) Magnetic separation from superparamagnetic particle suspensions. J Magn Magn Mater 321:2251–2256CrossRefGoogle Scholar
  34. Smistrup K, Hansen O, Bruus H, Hansen MF (2005) Magnetic separation in microfluidic systems using microfabricated electromagnets—experiments and simulations. J Magn Magn Mater 293:597–604CrossRefGoogle Scholar
  35. Suzuki H, Ho C-M, Kasagi N (2004) A chaotic mixer for magnetic bead-based micro cell sorter. J Microelectromech Syst 13:779–790CrossRefGoogle Scholar
  36. Tibbe AGJ, de Grooth BG, Greve J, Dolan GJ, Rao C, Terstappen LWMM (2002) Magnetic field design for selecting and aligning immunomagnetic labeled cells. Cytometry 47:163–172CrossRefGoogle Scholar
  37. Wang Y, Zhe J, Chung BTF, Dutta P (2008) A rapid magnetic particle driven Microstirrer. Microfluid Nanofluid 4:375–389CrossRefGoogle Scholar
  38. Wu Z, Li D (2008) Micromixing using induced-charge electrokinetic flow. Electrochim Acta 53:5827–5835CrossRefGoogle Scholar
  39. Xia N, Hunt TP, Mayers BT, Alsberg E, Whitesides GM, Westervelt RM, Ingber DE (2006) Combined microfluidic-micromagnetic separation of living cells in continuous flow. Biomed Microdevices 8:299–308CrossRefGoogle Scholar
  40. Yung CW, Fiering J, Mueller AJ, Ingber DE (2009) Micromagnetic—microfluidic blood cleansing device. Lab Chip 9:1171–1177CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.Department of Power EngineeringJadavpur UniversityKolkataIndia
  2. 2.Institute for Nano- and Micro Process TechnologyUniversität HannoverHannoverGermany
  3. 3.Center of Smart Interfaces, TU DarmstadtDarmstadtGermany

Personalised recommendations