Surface-Modified Poly(methyl methacrylate) Capillary Electrophoresis Microchips for Protein and Peptide Analysis

Abstract

Polymeric materials have emerged as appealing alternatives to conventional inorganic substrates for the fabrication of microscale analytical systems; however, native polymeric surfaces typically require covalent modification to ensure optimum biocompatibility. 2-Bromoisobutyryl bromide was immobilized on poly(methyl methacrylate) (PMMA) substrates activated using an oxygen plasma. Atom-transfer radical polymerization was then performed to graft poly(ethylene glycol) (PEG) on the PMMA surface. PMMA microcapillary electrophoresis (μCE) devices made with the covalently modified surfaces exhibited substantially reduced electroosmotic flow and nonspecific adsorption of proteins on microchannel surfaces. Experiments using fluorescein isothiocyanate-conjugated bovine serum albumin indicated that both column efficiency and migration time reproducibility were 1 order of magnitude better with derivatized compared to untreated PMMA μCE chips. Fast, reproducible, and efficient separations of proteins and peptides were demonstrated using the PEG-grafted PMMA μCE chips. All analyses were completed in less than 60 s, and separation efficiencies as high as 5.2 × 104 plates for a 3.5-cm-long separation channel were obtained. These results demonstrate the general applicability of surface-grafted PMMA microdevices for a broad range of protein analyses.

Capillary electrophoresis of proteins 2003–2005

“…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].…”

“…A number of CE steps and components that are used in fused-silica capillaries have been transferred and successfully tested on a microchip including preconcentration on porous silica membrane [22,23], automated derivatization [29], microreactor with immobilized proteases and other proteins [181,182], UV detector [183,184], chemiluminescence detector [34,185], multiwavelength LIF detector [186], UV LIF detector [98], wall coatings [82,85], affinity CE [129], CIEF [80], and sheathless electrospray for MS [113,114].…”

Microfluidic ELISA on non-passivated PDMS chip using magnetic bead transfer inside dual networks of channels

“…The two networks are linked by the fluidic bridges (7). (b) Control level: the control level is composed of a single closed channel (8) fanning into eight branches to form the pressure valves (9) 20 PSI in the control line was found to be appropriate to completely and reversibly close the eight valves without disrupting the flow in the outlet channels (Fig. 3).…”

“…Many research groups have investigated chemical surface modifications of various polymeric materials to limit the effects of NSA. [6][7][8][9][10][11][12] In particular, surface modifications of poly(dimethylsiloxane) (PDMS) have been extensively explored as it is currently the preferred polymer for biochip fabrication. [13][14][15][16][17][18][19][20][21] Despite many advantages, PDMS is notorious for its high native hydrophobicity and its tendency to rapidly adsorb biological materials.…”

Surface treatment and characterization: Perspectives to electrophoresis and lab‐on‐chips

“…Liu et al [205] also reported the use of ATRP for microchip surface modification. They grafted PEG on a PMMA microchip after the immobilization of a typical ATRP initiator, 2-bromoisobutyryl bromide.…”