“Click” chemistry‐based surface modification of poly(dimethylsiloxane) for protein separation in a microfluidic chip

Abstract

"Click" chemistry-based surface modification strategy was developed for PDMS microchips to enhance separation performance for both amino acids and proteins. Alkyne-PEG was synthesized by a conventional procedure and then "click" grafted to azido-PDMS. FTIR absorption by attenuated total reflection and contact angle measurements proved efficient grafting of alkyne-PEG onto PDMS surface. Manifest EOF regulation and stability of PEG-functionalized PDMS microchips were illustrated via EOF measurements and protein adsorption investigations. The stability of nonspecific protein adsorption resistance property was investigated up to 30 days. Separation of fluorescence-labeled amino acids and proteins was further demonstrated with high repeatability and reproducibility. Comparison of protein separation using PDMS microchips before and after surface modification suggested greatly improved electrophoretic performance of the PEG-functionalized PDMS microchips. We expect the "click" chemistry-based surface modification method to have wide applications in microseparation of proteins with long-term surface stability.

Recent advances in nonbiofouling PDMS surface modification strategies applicable to microfluidic technology

“…To this end, for reducing nonspecific protein adsorption, Zhang et al modified O 2 plasma-pretreated PDMS microchannels with 3-glycidoxypropyltrimethoxysilane (GPTMS) and 3-chloropropyltrichlorosilane (CPTMS) which were then exposed to a NH 2 -PEG and alkyne-PEG solutions, respectively 116,117 . Surface modification by this two-step grafting method was verified by the FTIR-attenuated total reflection (FTIR-ATR) spectra.…”

Physisorbed surface coatings for poly(dimethylsiloxane) and quartz microfluidic devices

“…A second approach involves chemical or photochemical modification of the cured PDMS surfaces in which covalent bonds are formed between surface functional groups and reactive groups of the coating agents. Recent examples include UV-initiated grafting using different initiators [30-32] as well as chemical grafting of alkyne-PEG [33], polyethylene glycol monoacrylate, polyethylene glycol diacrylate [34], and immobilization of poly( l -glutamic acid) to PDMS [35]. These surface modifications are usually very stable but require specific functional groups on the microchannel surface targeting a reactive group of the coating agent.…”

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].…”