Electrokinetic characterization of individual nanoparticles in nanofluidic channels
- 508 Downloads
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.
KeywordsTotal 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.
- Axelrod D, Burghardt T, Thompson N (1984) Total internal reflection fluorescence. Ann Rev Biophys Bioeng 93(13):247–268Google Scholar
- Blair D, Dufresne E (2007) The matlab particle tracking code repository. http://physics.georgetown.edu/matlab/
- Fraikin J, Teesalu T, McKenney C, Ruoslahti E, Cleland A (2011) A high-throughput label-free nanoparticle analyser. Nat Nanotechnol 6:308–313Google Scholar
- Happel J, Brenner H (1991) Low Reynolds Number Hydrodynamics. Kluwer Academic, DordrechtGoogle Scholar
- Hunter R (1993) Foundations of colloid science. Oxford Science Publication, OxfordGoogle Scholar
- Kirby B (2010) Micro- and nanoscale fluid mechanics. Cambridge University Press, CambridgeGoogle Scholar
- Li HF, Yoda M (2008) Multilayer nano-particle image velocimetry (mnpiv) in microscale poiseuille flows. Meas Sci Technol 19(7):075,402Google Scholar
- Probstein R (1994) Physicochemical hydrodynamics: an introduction. Wiley, New YorkGoogle Scholar