Microfluidics and Nanofluidics

, Volume 12, Issue 1–4, pp 411–421 | Cite as

Electrokinetic characterization of individual nanoparticles in nanofluidic channels

  • Thomas M. Wynne
  • Alexander H. Dixon
  • Sumita Pennathur
Research Paper


We electrokinetically characterize properties of single 42-nm polystyrene nanoparticles (NP) in nanofluidic channels imaged with frustrated total internal reflection fluorescence microscopy (fTIRFM). Specifically, we demonstrate fTIRFM of individual NPs in nanofluidic channels shallower than the evanescent field and use the resultant illumination field to gain insight into the behavior and electrokinetic properties of individual NP transport in channels. We find that the electrophoretic mobility of nanoparticles in 100-nm channels is lower than in larger channels or in bulk, presumably due to hindrance effects. Furthermore, we notice a non-intuitive increase in mobility with buffer concentration, which we attribute to electric double layer interactions. Finally, since the evanescent field intensity decreases with distance from the channel wall, we use the measured fluorescence intensity to report probable transverse distributions of free-solution 42-nm polystyrene fluorescent particles. Our method promises to be useful for characterizing nanoscale molecules for many applications in drug discovery, bioanalytics, nanoparticle synthesis, viral targeting, and the basic science of understanding nanoparticle behavior.


Total internal reflection fluorescence Nanofluidics Nanoparticles 



This work is supported by a grant from the Institute for Collaborative Biotechnologies through contract no. W911NF-09- D-0001 from the U.S. Army Research Office.


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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Thomas M. Wynne
    • 1
  • Alexander H. Dixon
    • 1
  • Sumita Pennathur
    • 1
  1. 1.Department of Mechanical EngineeringUniversity of CaliforniaSanta BarbaraUSA

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