Application of plasma-polymerized films for isoelectric focusing of proteins in a capillary electrophoresis chip

Abstract

The first use of plasma polymerization technique to modify the surface of a glass chip for capillary isoelectric focusing (cIEF) of different proteins is reported. The electrophoresis separation channel was machined in Tempax glass chips with length 70 mm, 300 microm width and 100 microm depth. Acetonitrile and hexamethyldisiloxane monomers were used for plasma polymerization. In each case 100 nm plasma polymer films were coated onto the chip surface to reduce protein wall adsorption and minimize the electroosmotic flow. Applied voltages of 1000 V, 2000 V and 3000 V were used to separate mixtures of cytochrome c (pI 9.6), hemoglobin (pI 7.0) and phycocyanin (pI 4.65). Reproducible isoelectric focusing of each pI marker protein was observed in different coated capillaries at increasing concentration 2.22-5 microg microL(-1). Modification of the glass capillary with hydrophobic HMDS plasma polymerized films enabled rapid cIEF within 3 min. The separation efficiency of cytochrome c and phycocyanin in both acrylamide and HMDS coated capillaries corresponded to a plate number of 19600 which compares favourably with capillary electrophoresis of neurotransmitters with amperometric detection.

Nanocomposite and Nanostructured Carbon-based Films as Growth Substrates for Bone Cells

“…These films have a broad spectrum of applications, including use in medicine and various biotechnologies (for a review, see Biederman 2004). For example, plasma polymers have been used for the creation of antibacterial coatings of body implants and other medical devices (Vasilev et al, 2010), surfaces for studying protein adsorption (Zhang and Feng 2007), protein interaction (Menzies et al, 2010), protein separation (Tsai et al, 2003), and also for immobilization of proteins (Kim et al, 2003), e.g., enzymes, such as lysozyme (Thierry et al, 2008) or trypsin (Abbas et al, 2009). Plasma polymer films with immobilized heparin can serve as hemocompatible surfaces preventing blood coagulation .…”

Tunable in-situ electro-polymerization of hydrogel films for microchip-based bioanalysis

“…A second example involves isoelectric focusing of proteins in microfluidic systems, where distinct spatial zones with fixed pH must be established to capture proteins based on their isoelectric points (pI). 16,17 Our method offers a pathway to address this need by employing monomers that contain buffering groups (e.g., immobilines 18 incorporating both double bonds for polymerization and weak acid or basic groups to maintain local pH). Films polymerized from these monomers would embed sufficient buffering power to maintain the local pH within a precisely determined range.…”

Capillary electrophoresis of proteins 2003–2005

“…However, a growing number of research groups perform CIEF on chips [81,146,147]. Recently, whole-column detection was introduced to CIEF [21,94,97,148,149], which allows monitoring dynamics of CIEF.…”

“…Other permanent coatings were prepared with dextran on silanized fused-silica capillary [79], hexamethyl disiloxane plasma polymerized with 2.3-epoxy-1-propanol on glass microchip [80,81], fluorinated aromatic hydrocarbons attached to PDMS by chemical vapor deposition [82], trimethoxysilane-modified poly(dimethyl acrylamide) [83], poly(vinyl alcohol) thermally immobilized on oxygen plasma-pretreated PDMS [84], and PEG grafted on Plexiglas surface [85].…”