title: Nonfouling hydrophilic poly(ethylene glycol) engraftment strategy for PDMS/SU-8 heterogeneous microfluidic devices.
abstract: We report a novel nonfouling passivation method using poly(ethylene glycol) (PEG) engraftment on the surfaces of poly(dimethylsiloxane) (PDMS) microfluidic devices sealed with SU-8. To achieve bonding between the PDMS and SU-8 surfaces, the PDMS surface was first functionalized with amines by treatment with 3-aminopropyltrimethoxysilane (APTMS) for subsequent reaction with epoxide functional groups on SU-8 surfaces. To modify the heterogeneous surfaces of the resulting PDMS/SU-8 microfluidic device further, the remaining SU-8 surfaces were amino functionalized using ethylene diamine (EDA), followed by treating both amino-functionalized PDMS and SU-8 surfaces with mPEG-NHS (N-hydroxysuccinimide) through an amine-NHS reaction for facile PEG immobilizations, thus simultaneously modifying both PDMS and SU-8 surfaces in one reaction. Detailed surface analyses such as the water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) were conducted to confirm the chemical reactions and characterize the resulting surface properties. To test the efficacy of this surface-modification strategy, we conducted nonspecific protein and particle binding tests using microfluidic devices with and without modifications. The PEG-modified PDMS/SU-8 device surfaces showed a 64.5% reduction in nonspecific bovine serum albumin (BSA) adsorption in comparison to that of the unmodified surfaces and 92.0 and 95.8% reductions in microbead adhesion under both stagnant and flowing conditions, respectively.
authors.affiliation: Department of Chemical and Biological Engineering, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Po Ying
authors.initials: PY
authors.lastname: Yeh
authors.forename: Zhiyi
authors.initials: Z
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Lin
authors.forename: Xudong
authors.initials: X
authors.lastname: Cao
mesh_terms: D000327:Adsorption; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D005029:Ethylenediamines / Q000737:chemistry; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D018625:Microscopy, Atomic Force; D056951:Photoelectron Spectroscopy; D011092:Polyethylene Glycols / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013499:Surface Properties
chemical_list: D004129:Dimethylpolysiloxanes; D005029:Ethylenediamines; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; C031234:ethylenediamine; C013830:baysilon