Micellar electrokinetic chromatography of fluorescently labeled proteins on poly(dimethylsiloxane)‐based microchips

Abstract

MEKC of standard proteins was investigated on PDMS microfluidic devices. Standard proteins were labeled with AlexaFluor(R) 488 carboxylic acid tetrafluorophenyl ester and filtered through a size-exclusion column to remove any small peptides and unreacted label. High-efficiency MEKC separations of these standard proteins were performed using a buffer consisting of 10 mM sodium tetraborate, 25 mM SDS, and 20% v/v ACN. A separation of BSA using this buffer in a 3.0 cm long channel generated a peak with a plate height of 0.38 microm in <20 s. Additional fast separations of myoglobin, alpha-lactalbumin, lysozyme, and cytochrome c also yielded peaks with plate heights ranging from 0.54 to 0.72 microm. All proteins migrated with respect to their individual pIs. To improve the separations, we used a PDMS serpentine chip with tapered turns and a separation distance of 25 cm. The number of plates generated increased linearly with increasing separation distance on the extended separation channel chips; however, the resolution reached an asymptotic value after about 7 cm. This limited the peak capacity of the separation technique to 10-12.

A novel, environmentally friendly sodium lauryl ether sulfate‐, cocamidopropyl betaine‐, cocamide monoethanolamine‐containing buffer for MEKC on microfluidic devices

“…The separations using the 5.0% Seventh Generation TM dishwashing liquid yielded the fastest separations where all peaks were sufficiently resolved, with resolution of at least 1.5. The Seventh Generation TM buffer successfully separated the amino acids with nice Gaussian-shaped peaks faster than previously optimized buffers developed in our group using SDS [20,21] and with equal or higher separation efficiencies. For example, the final peak, i.e.…”

Recent innovations in protein separation on microchips by electrophoretic methods

“…A recent article from the group of Culbertson [90] reported the use of MEKC on PDMS chips, to achieve the separation of fluorescently tagged cytochrome c, lysozyme, a-lactalbumin, BSA, ribonuclease A, and myoglobin. The adsorption of proteins on this material was overcome by using the micellar strategy and by adapting surface modification.…”

Silicones for Microfluidic Systems

“…• Separation (purifi cation or enrichment) of biomolecules [84,162] (amino acids [83,84,[163][164][165][166], peptides [77,155] proteins [77,89,[167][168][169][170][171][172] neurotransmitters [71,152,163] and DNA [162,[172][173][174][175][176]). • Immobilization of biomolecules for biomolecular detection using immunoassays [35,75,[177][178][179][180] and enzymatic microreactors [181,182].…”