Direct observation of transitions between surface-dominated and bulk diffusion regimes in nanochannels.
The diffusion of charged proteins in liquid-filled nanometer-sized apertures with charged surfaces has been investigated with fluorescence correlation spectroscopy (FCS). Based on a two-dimensional (2D) multicomponent diffusion model, key parameters such as the number of molecules diffusing freely inside the nanochannel or interacting with the surfaces, together with the specific diffusion parameters, could be extracted. Different regimes of diffusion have been observed and described by a model, which takes into account the steric exclusion, the reversible surface adsorption of the biomolecules, and the exclusion-enrichment effect that is due to the charge of the proteins and the ionic strength of the solution. Conditions where the diffusion of proteins through nanoconfined spaces can be of the same magnitude as in the bulk were both predicted and experimentally verified.
Durand
Nicolas F Y
NF
Microsystems Laboratory, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland. nicolas.durand@epfl.ch
Dellagiacoma
Claudio
C
Goetschmann
Raphaël
R
Bertsch
Arnaud
A
Märki
Iwan
I
Lasser
Theo
T
Renaud
Philippe
P
D000465:Algorithms; D004058:Diffusion; D005456:Fluorescent Dyes / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation / Q000379:methods*; D013499:Surface Properties; D014909:Wheat Germ Agglutinins / Q000032:analysis* / Q000737:chemistry
D005456:Fluorescent Dyes; D014909:Wheat Germ Agglutinins