Permanent surface modification of polymeric capillary electrophoresis microchips for protein and peptide analysis

Abstract

Because of their surface heterogeneity, proteins readily adsorb on polymeric substrates via various interactions, which adversely affects the performance of polymeric microfluidic devices in electrophoresis-based protein/peptide analysis. Therefore, it is necessary to use surface modification techniques such as dynamic coating or more complicated permanent surface modification, which has broader application and better performance, to render the polymeric microchannels protein-resistant. This manuscript is a review of the surface chemistry of microfluidic devices used for electrophoretic separations of proteins and peptides. The structural complexity of proteins as it relates to adsorption is described, followed by a review of the mechanisms and structural characteristics of protein-resistant surfaces. Permanent surface modification techniques used in grafting protein-resistant materials onto the surfaces of electrophoresis microchannels fabricated from polymer substrates are summarized and successful examples are presented.

Selective modification for polydimethylsiloxane chip by micro-plasma

“…Chemical and physical modifications of the surface of microfluidic channel is a state-of-the-art technique to control the surface charge and hydrophilicity in the micro analysis system [1][2][3][4][5][6][7][8][9]. Micro-plasma technique has received special attention due to its application in surface modification as well as on-chip light sources and chromatography detectors [1,10].…”

“…However, the extremely hydrophobic property of PDMS surface limits the extent of its applications. As a result, many different methods for hydrophilization have been proposed to modify the surface of PDMS, such as rendering it hydrophilic by activating PDMS surface using oxygen plasma [9] and absorbed hydrophilic organic molecules coatings [8,12], nonetheless at the expense of its long-term stability [3]. Another conventional way of surface modification in polymer science is surface-attached polymerization, which provides chemically stable surfaces due to the covalent bonding of the polymer chains to the substrate [4][5][6]9].…”

“…As a result, many different methods for hydrophilization have been proposed to modify the surface of PDMS, such as rendering it hydrophilic by activating PDMS surface using oxygen plasma [9] and absorbed hydrophilic organic molecules coatings [8,12], nonetheless at the expense of its long-term stability [3]. Another conventional way of surface modification in polymer science is surface-attached polymerization, which provides chemically stable surfaces due to the covalent bonding of the polymer chains to the substrate [4][5][6]9]. Recent reports also introduce grafting of poly (acrylic acid) (PAA) on PDMS based on a liquid phase system with UV irradiation [4,5,13,14], however such method demands long operation hours, and requires strictly experimental conditions and abundant chemicals as well, some result in PDMS swelling in organic solvents, and the others poor stability and performance.…”

Universal hydrophilic coating of thermoplastic polymers currently used in microfluidics

“…The various developed polymer surface modification techniques have been reported in several reviews (9)(10)(11)(12)(13). The most common modification methods fall into three categories: gas-phase processing, wet chemical methods and a combination of both.…”

PMMA Polymer Membrane-Based Single Cylindrical Submicron Pores: Electrical Characterization and Investigation of Their Applicability in Resistive-Pulse Biomolecule Detection

“…Besides, the surface properties of the membrane can be modified for longer terms by either inducing chemical reactions based on oxygen plasma treatment or by photochemical modifications involving UV surface exposure [33,34].…”