Dynamic Cross-Linking Effect of Mg²⁺ To Enhance Sieving Properties of Low-Viscosity Poly(vinylpyrrolidone) Solutions for Microchip Electrophoresis of Proteins

Abstract

We report a dynamic cross-linking effect of Mg2+ that enhances the sieving properties of low-viscosity poly(vinylpyrrolidone) (PVP) solutions. A low-viscosity PVP solution was applied to nondenaturing microchip electrophoresis of protein samples using microchips made of poly(methyl methacrylate). The separation resolution of nondenatured protein markers in 1.8% PVP solution was improved by adding 1-20 mM MgCl2. We studied the effect of the ratio of cross-linking agent on mobility of protein samples and showed that protein retardation (ln micro/micro0) is correlated with the ratio of cross-linking agent to PVP ([cMg2+/cPVP]) as ln micro/micro0=A'[cMg2+/cPVP]b'. A' was related to the protein radius (R), and b' was found to be 0.72 for proteins with R=2.4 nm and 0.82 for proteins with R=1.85 nm. A structural study of PVP in semidilute solutions using dynamic light scattering showed that incremental increases of Mg2+ ion concentration from 5 to 20 mM in 1.8% PVP solution increased the hydrodynamic radius of PVP polymers by 20%.

Characterization of low viscosity polymer solutions for microchip electrophoresis of non-denatured proteins on plastic chips

“…23 We have been studying different aspects of electrophoretic separation of non-denatured protein samples on plastic microchips using high and low viscosity polymers. 24 In the current research, we chose a series of water soluble polymers with different hydrophilicity for application to microchip electrophoresis of protein samples in a PMMA microchip. We studied different characteristics of the microchannels such as protein adsorption, wettability, EOF, and separation efficiency for separation of protein samples in solutions of these polymers.…”

Direct Determination of Native Proteins in Miniaturized Capillary Electrophoresis System

“…Miniaturized capillary electrophoresis and chip electrophoresis systems are the most attractive examples of lab-on-chip applications especially for protein separation and their analysis in biological fluids. [1][2][3][4][5][6][7] A detailed outline of the most recent advances in the development of microchips devoted to protein analyses focusing on those integrating or relying on electrokinetic separation processes is reported by Peng et al 8 This review highlights novel developments associated with electrokinetic fluidic systems. In the literature there are a few studies on protein analysis by using miniaturized capillary electrophoresis * Author to whom correspondence should be addressed.…”

Polymer sieving matrices in microanalytical electrophoresis

“…32,33,39,42,47,56,57 The researchers reported SDS CGE of proteins on a PEG-coated commercial PMMA microuidic chip. 32 Here, a covalently attached PEG coating effectively suppressed protein adsorption.…”