PMID- 19458869
OWN - NLM
STAT- MEDLINE
DCOM- 20090831
LR  - 20091119
IS  - 1473-0197 (Print)
IS  - 1473-0189 (Linking)
VI  - 9
IP  - 11
DP  - 2009 Jun 7
TI  - Effect of wall-molecule interactions on electrokinetic transport of charged 
      molecules in nanofluidic channels during FET flow control.
PG  - 1601-8
LID - 10.1039/b901382m [doi]
AB  - The interactions between charged molecules and channel surfaces are expected to 
      significantly influence the electrokinetic transport of molecules and their 
      separations in nanochannels. This study reports the effect of wall-molecule 
      interactions on flow control of negatively charged Alexa 488 and positively 
      charged Rhodamine B dye molecules in an array of nanochannels (100 nm wx 500 nm 
      dx 14 mm l) embedded in fluidic field effect transistors (FETs). For FET flow 
      control, a third electrical potential, known as a gate bias, is applied to the 
      channel walls to manipulate their zeta-potential. Electroosmotic flow of charged 
      dye molecules is accelerated or reversed according to the polarity and magnitude 
      of the gate bias. During FET flow control, we monitor how the electrostatic 
      interaction between charged dye molecules and channel walls affects the apparent 
      velocity of molecules, using laser-scanning confocal fluorescence microscopy. We 
      observe that the changes in flow speed and direction of negatively charged Alexa 
      488 is much more pronounced than that of positively charged Rhodamine B in 
      response to the gate bias that causes either repulsive or attractive 
      electrostatic interactions. This observation is supported by calculations of 
      concentration-weighted velocity profiles of the two dye molecules during FET flow 
      control. The velocity profile of negatively charged Alexa 488 is much more 
      pronounced at the center of each nanochannel than near its walls since Alexa 488 
      molecules are repelled from negatively charged channel walls. This pronounced 
      center velocity further responds to the gate bias, increasing the average 
      velocity by as much as 23% when -30 V is applied to the gate (zeta-potential = 
      -80.6 mV). In contrast, the velocity profile of positively charged Rhodamine B is 
      dispersed over the entire channel width due to dye-wall attraction and 
      adsorption. Our experimental observations and calculations support the hypothesis 
      that valence-charge-dependent electrostatic interaction and its manipulation by 
      the gate bias would enhance molecular separations of differentially charged 
      molecules in nanofluidic FETs.
FAU - Oh, Youn-Jin
AU  - Oh YJ
AD  - Department of Chemical and Nuclear Engineering, University of New Mexico, 
      Albuquerque, New Mexico 87131, USA.
FAU - Garcia, Anthony L
AU  - Garcia AL
FAU - Petsev, Dimiter N
AU  - Petsev DN
FAU - Lopez, Gabriel P
AU  - Lopez GP
FAU - Brueck, Steven R J
AU  - Brueck SR
FAU - Ivory, Cornelius F
AU  - Ivory CF
FAU - Han, Sang M
AU  - Han SM
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20090312
PL  - England
TA  - Lab Chip
JT  - Lab on a chip
JID - 101128948
RN  - 0 (Fluorescent Dyes)
SB  - IM
MH  - Adsorption
MH  - *Electricity
MH  - Electroosmosis/*instrumentation
MH  - Fluorescent Dyes/chemistry
MH  - Microfluidic Analytical Techniques/*instrumentation
MH  - Microscopy, Confocal
MH  - Surface Properties
MH  - Transistors, Electronic
EDAT- 2009/05/22 09:00
MHDA- 2009/09/01 06:00
CRDT- 2009/05/22 09:00
PHST- 2009/05/22 09:00 [entrez]
PHST- 2009/05/22 09:00 [pubmed]
PHST- 2009/09/01 06:00 [medline]
AID - 10.1039/b901382m [doi]
PST - ppublish
SO  - Lab Chip. 2009 Jun 7;9(11):1601-8. doi: 10.1039/b901382m. Epub 2009 Mar 12.