Environmentally friendly surface modification of PDMS using PEG polymer brush

Abstract

A PEG-NH2-based environmentally friendly surface modification strategy was developed for PDMS microchips to prevent protein adsorption and to enhance separation performance. PEG-NH2 was synthesized using a modified synthesis procedure. A two-step grafting method was used for PDMS modification. FTIR absorption by attenuated total reflection and contact angle measurements verified the successful grafting of PEG-NH2 onto the PDMS surface. Subsequent EOF Measurements and protein adsorption studies of PEG-modified PDMS microchips revealed noticeable EOF suppression and resistance to nonspecific protein adsorption for more than 30 days. Separation of four FITC-labeled amino acids was further demonstrated with high repeatability and reproducibility. Comparison of electrophoresis of 3-(2-furoyl)quinoline-2-carboxaldehyde-labeled BSA using PDMS microchips before and after surface modification resulted in significantly improved electrophoretic performance of the PEG-modified PDMS microchips, suggesting that our PEG grafting method successfully modified PDMS surface property and prevented adsorption of proteins. We expect that this environmentally friendly surface modification method will be useful for future protein separations with long-term surface stability.

Suppressing Surface Reconstruction of Superhydrophobic PDMS Using a Superhydrophilic Zwitterionic Polymer

“…Due to its superhydrophobicity and low glass transition temperature, PDMS polymer chains will rearrange and undo most surface coatings. 10-13 This is commonly referred to as hydrophobic regeneration (Figure 1a). 8 Thus, these modifications often last only a few hours or sometimes a matter of minutes (Figure 1b).…”

“…Despite their ubiquitous use, PEG coatings are unstable, which has been a well-known problem for years due to reconstruction that occurs at the interface between the PDMS and PEG polymers (Figure 1c). 11, 13, 17 While PEG is often considered a hydrophilic polymer, this material is in fact amphiphilic, being soluble in such non-polar solvents such as dichloromethane and toluene, in addition to water.…”

Silicones for Microfluidic Systems

“…SAM can act as single functional layers or intermediate anchoring layers for graft ing of polymer chains or surface-confi ned polymerization. • Covalent polymer coatings using "graft ing to" (end-functionalized oligomers tethered by hydrosilylation reaction [81,82], addition of amine functions to epoxides [83] or "click chemistry" [84] to the activated surface or reactive anchoring layer) and "graft ing from" techniques (free radical UV mediated polymerization [85][86][87] and controlled radical polymerization (ARTP) [88][89][90], plasmabased polymerization [36,91], polymerization by chemical vapor deposition (CVD) [92]). …”

“…• 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].…”

Enhanced electrophoresis separation of non-electroactive amino acids on poly(dimethylsiloxane) microchip coupled with direct electrochemical detection on a copper electrode

“…The end-channel detection mode employed here enabled easier electrode/channel alignment and substantially increased the reproducibility of electrode response. To ensure efficient electrophoresis separation of amino acids on PDMS microchip, a variety of polymeric materials such as PVA (Wu et al 2005(Wu et al , 2006, PVP (Wu et al 2006), PEG (Wang et al 2008;Zhang et al 2009), etc., have been derived for surface modifications of the microchannel wall. Recently, we and other groups reported an approach to the fabrication of antifouling PDMS surface through layer-by-layer assembling of TiO 2 NPs (Roman and Culbertson 2006;Qiu et al 2009).…”