PMID- 17073411
OWN - NLM
STAT- MEDLINE
DCOM- 20070419
LR  - 20061031
IS  - 0003-2700 (Print)
IS  - 0003-2700 (Linking)
VI  - 78
IP  - 21
DP  - 2006 Nov 1
TI  - Generation of hydrophilic poly(dimethylsiloxane) for high-performance microchip 
      electrophoresis.
PG  - 7446-52
AB  - Poly(dimethylsiloxane) (PDMS) has become one of the most widely used materials 
      for microchip capillary electrophoresis and microfluidics. The popularity of this 
      material is the result of its low cost, simple fabrication, and rugged 
      elastomeric properties. The hydrophobic nature of PDMS, however, limits its 
      applicability for microchip CE, microfluidic patterning, and other 
      nonelectrophoresis applications. The surface of PDMS can be made hydrophilic 
      using a simple air plasma treatment; however, this property is quickly lost 
      through hydrophobic recovery caused by diffusion of unreacted oligomer to the 
      surface. Here, a simple approach for the generation of hydrophilic PDMS with 
      long-term stability in air is presented. PDMS is rendered hydrophilic through a 
      simple two-step extraction/oxidation process. First, PDMS is extracted in a 
      series of solvents designed to remove unreacted oligomers from the bulk phase. 
      Second, the oligomer-free PDMS is oxidized in a simple air plasma, generating a 
      stable layer of hydrophilic SiO2. The conversion of surface-bound siloxane to 
      SiO2 was followed with X-ray photoelectron spectroscopy. SiO2 on 
      extracted-oxidized PDMS was stable for 7 days in air as compared to less than 3 h 
      for native PDMS. Furthermore, the contact angle for modified PDMS was reduced to 
      <40 degrees and remained low throughout the experiments. As a result of the 
      decreased contact angle, capillary channels self-wet through capillary action, 
      making the microchannels much easier to fill. Finally, the modification 
      significantly improved the performance of the devices for microchip 
      electrophoresis. The electroosmotic flow increased from 4.1 x 10(-4) to 6.8 x 
      10(-4) cm(2)/V.s for native compared to oxidized PDMS. Separation efficiencies 
      for electrochemical detection also increased from 50 000 to 400 000 N/m for a 
      1.1-nL injection volume. The result of this modification is a significant 
      improvement in the performance of PDMS for microchip electrophoresis and 
      microfluidic applications.
FAU - Vickers, Jonathan A
AU  - Vickers JA
AD  - Department of Chemistry, Colorado State University, Fort Collins, Colorado 
      80523-1872, USA.
FAU - Caulum, Meghan M
AU  - Caulum MM
FAU - Henry, Charles S
AU  - Henry CS
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Anal Chem
JT  - Analytical chemistry
JID - 0370536
RN  - 0 (Dimethylpolysiloxanes)
RN  - 0 (Silicones)
RN  - 63148-62-9 (baysilon)
SB  - IM
MH  - Dimethylpolysiloxanes/*chemistry
MH  - Electrophoresis, Microchip/*methods
MH  - Oxidation-Reduction
MH  - Sensitivity and Specificity
MH  - Silicones/*chemistry
EDAT- 2006/11/01 09:00
MHDA- 2007/04/20 09:00
CRDT- 2006/11/01 09:00
PHST- 2006/11/01 09:00 [pubmed]
PHST- 2007/04/20 09:00 [medline]
PHST- 2006/11/01 09:00 [entrez]
AID - 10.1021/ac0609632 [doi]
PST - ppublish
SO  - Anal Chem. 2006 Nov 1;78(21):7446-52. doi: 10.1021/ac0609632.