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Samarasinghe TN, Zeng Y, Johnson CK. Comparison of separation modes for microchip electrophoresis of proteins. J Sep Sci 2020; 44:744-751. [PMID: 33226183 DOI: 10.1002/jssc.202000883] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/16/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022]
Abstract
Separation of a set of model proteins was tested on a microchip electrophoresis analytical platform capable of sample injection by two different electrokinetic mechanisms. A range of separation modes-microchip capillary zone electrophoresis, microchip micellar electrokinetic chromatography, and nanoparticle-based sieving-was tested on glass and polydimethylsiloxane/glass microchips and with silica-nanoparticle colloidal arrays. The model proteins calmodulin (18 kiloDalton), bovine serum albumin (66 kDa), and concanavalin (106 kDa) were labeled with Alexa Fluor 647 for laser-induced fluorescence detection. The best separation and resolution were obtained in a silica-nanoparticle colloidal array chip.
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Affiliation(s)
| | - Yong Zeng
- Department of Chemistry, University of Kansas, Lawrence, Kansas, USA
| | - Carey K Johnson
- Department of Chemistry, University of Kansas, Lawrence, Kansas, USA
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Jalili K, Abbasi F, Behboodpour L. In situ probing of switchable nanomechanical properties of responsive high-density polymer brushes on poly(dimethylsiloxane): An AFM nanoindentation approach. J Mech Behav Biomed Mater 2019; 93:118-129. [PMID: 30785077 DOI: 10.1016/j.jmbbm.2019.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 01/27/2019] [Accepted: 02/03/2019] [Indexed: 12/01/2022]
Abstract
Nanomechanical characteristics of end grafted polymer brushes were studied by AFM based, colloidal probe nanoindentation measurements. A high-density polymer brush of poly(2-hydroxyethyl methacrylate) (PHEMA) was precisely prepared on the surface of a flexible poly(dimethylsiloxane) (PDMS) substrate oxidized in ultraviolet/ozone (UVO). Exposure times less than 10min resulted in laterally homogeneous oxidized surfaces, characterized by a SiOx thickness ∼35nm and an increased modulus up to 9MPa, as shown by AFM nanoindentation measurements. We have demonstrated that a high surface density of up to ∼0.63chains/nm2 of the well-defined PHEMA brushes can be grown from the surface of oxidized PDMS by surface-initiated atom transfer radical polymerization (SI-ATRP) from trimethoxysilane derivatives mixed-SAM. The reversible nanomechanical changes of PHEMA layer between extended (hydrated state) and collapsed (dehydrated state) chain upon immersing in selective and non-selective solvents were investigated by in situ AFM nanoindentation analysis in liquid environments. The elastic modulus derived from force-indentation curves obtained for swollen PHEMA grafted chains in water was estimated to be equal 2.7±0.2MPa, which is almost two orders of magnitude smaller than the modulus of dry PHEMA brush. Additionally, under cyclohexane immersion, the modulus of the PHEMA layer decreased by one order of magnitude, indicating a more compact chain packing at the PDMS surface.
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Affiliation(s)
- K Jalili
- Institute of Polymeric Materials, Sahand University of Technology, P.O.Box 51335-1996, Tabriz, Iran; Faculty of Polymer Engineering, Sahand University of Technology, Tabriz, Iran; Max Planck Institute for Polymer Research, 10 Ackermannweg, 55128 Mainz, Germany.
| | - F Abbasi
- Institute of Polymeric Materials, Sahand University of Technology, P.O.Box 51335-1996, Tabriz, Iran; Faculty of Polymer Engineering, Sahand University of Technology, Tabriz, Iran
| | - L Behboodpour
- Institute of Polymeric Materials, Sahand University of Technology, P.O.Box 51335-1996, Tabriz, Iran; Faculty of Polymer Engineering, Sahand University of Technology, Tabriz, Iran
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Saari NAN, Mislan AA, Hashim R, Zahid NI. Self-Assembly, Thermotropic, and Lyotropic Phase Behavior of Guerbet Branched-Chain Maltosides. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:8962-8974. [PMID: 29999321 DOI: 10.1021/acs.langmuir.8b01899] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Five synthetic β-d-maltosides derived from Guerbet branched alcohols, whose total hydrocarbon chain length ranged from C8 to C24, were synthesized to a high anomeric purity, and their thermal properties, liquid-crystalline phases, and structures were characterized using differential scanning calorimetry, optical polarizing microscopy, and small-angle X-ray scattering. Thermal investigations of all anhydrous Guerbet maltosides showed that they do not form solid crystals but undergo a glass transition upon temperature change in the range of 35-53 °C. The glassy crystalline structure turns into the liquid-crystalline structure upon heating or addition of water. In thermotropic studies, the lamellar phase formation is prominent in shorter-chain-length analogues, whereas the longer-chain compounds exhibit a more frustrated form of self-assembly in the formation of a metastable state, polymorphism, and inverse bicontinuous cubic structure ( Ia3 d). The excess water conditions show that the phase formation is dominated by the lamellar phase for the longer-chain compounds. Normal micellar solution was observed in the shortest-chain-length maltosides because of the enlargement of hydrated maltose headgroups. The self-assembly of both dry and fully hydrated Guerbet maltosides, which exhibited glass-forming abilities and showed surface activity and also the ability to act as membrane-stabilizing compounds, makes them ideal candidates for practical use in industry as well as biomedical research.
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Affiliation(s)
- N A Nabila Saari
- Centre for Fundamental and Frontier Sciences in Nanostructure Self-Assembly, Department of Chemistry, Faculty of Science , University of Malaya , 50603 Kuala Lumpur , Malaysia
| | - Azwa Amanina Mislan
- Centre for Fundamental and Frontier Sciences in Nanostructure Self-Assembly, Department of Chemistry, Faculty of Science , University of Malaya , 50603 Kuala Lumpur , Malaysia
| | - Rauzah Hashim
- Centre for Fundamental and Frontier Sciences in Nanostructure Self-Assembly, Department of Chemistry, Faculty of Science , University of Malaya , 50603 Kuala Lumpur , Malaysia
| | - N Idayu Zahid
- Centre for Fundamental and Frontier Sciences in Nanostructure Self-Assembly, Department of Chemistry, Faculty of Science , University of Malaya , 50603 Kuala Lumpur , Malaysia
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Xiong B, Ren K, Shu Y, Chen Y, Shen B, Wu H. Recent developments in microfluidics for cell studies. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:5525-32. [PMID: 24536032 DOI: 10.1002/adma.201305348] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 12/09/2013] [Indexed: 05/23/2023]
Abstract
As a technique for precisely manipulating fluid at the micrometer scale, the field of microfluidics has experienced an explosive growth over the past two decades, particularly owing to the advances in device design and fabrication. With the inherent advantages associated with its scale of operation, and its flexibility in being incorporated with other microscale techniques for manipulation and detection, microfluidics has become a major enabling technology, which has introduced new paradigms in various fields involving biological cells. A microfluidic device is able to realize functions that are not easily imaginable in conventional biological analysis, such as highly parallel, sophisticated high-throughput analysis, single-cell analysis in a well-defined manner, and tissue engineering with the capability of manipulation at the single-cell level. Major advancements in microfluidic device fabrication and the growing trend of implementing microfluidics in cell studies are presented, with a focus on biological research and clinical diagnostics.
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Affiliation(s)
- Bin Xiong
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Turner DK, Wayman AE, Rolando CN, Dande P, Carter PW, Remsen EE. Reduction of artifacts in fluorescence correlation spectroscopy due to sample adsorption on optical glass surfaces. APPLIED SPECTROSCOPY 2013; 67:692-698. [PMID: 23735256 DOI: 10.1366/12-06848] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The preparation of glass cell surfaces that are chemically functionalized with poly(ethylene glycol) (PEG) chains to reduce sample adsorption and their use in fluorescence correlation spectroscopy (FCS) is described. Optical glass coverslips were acid etched and reacted with either 750 Mr PEG (PEG-750) or 5000 Mr PEG (PEG-5000) to produce adsorption-resistant optical surfaces. FCS data for Nile red-loaded Triton X-100 micelles (NR-TX-100) and Alexa Fluor 555-labeled proteins, bovine serum albumin (BSA-A555), lipidized BSA (lipid-BSA-A555), and three low molecular weight dyes deposited on PEGylated coverslips were evaluated. Measurement artifacts due to sample adsorption on the PEG-5000 functionalized coverslips were reduced significantly for the majority of test materials. Calculations of translational diffusion coefficients and Stokes radii confirmed the effectiveness of this approach. PEG-5000 functionalized coverslips were demonstrated as more effective in inhibiting adsorption than PEG-750 functionalized coverslips. Neither of the functionalized coverslips inhibited the adsorption of one test compound, rhodamine B, a dye that adsorbs strongly on glass surfaces. The use of longer PEG chains in conjunction with chemical cross-linking is proposed for producing a denser, less porous PEG layer for the prevention of strongly glass-adsorbing fluorophores that do not interact with the PEG layer.
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Affiliation(s)
- Daniel K Turner
- Mund-Lagowski Department of Chemistry and Biochemistry, Bradley University, 1501 West Bradley Avenue, Peoria, Illinois 61625, USA
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Yoshizawa S. Micro and nanotechnological tools for study of RNA. Biochimie 2012; 94:1588-94. [PMID: 22484393 DOI: 10.1016/j.biochi.2012.03.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2012] [Accepted: 03/22/2012] [Indexed: 11/16/2022]
Abstract
Micro and nanotechnologies have originally contributed to engineering, especially in electronics. These technologies enable fabrication and assembly of materials at micrometer and nanometer scales and the manipulation of nano-objects. The power of these technologies has now been exploited in analyzes of biologically relevant molecules. In this review, the use of micro and nanotechnological tools in RNA research is described.
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Affiliation(s)
- Satoko Yoshizawa
- Centre de Génétique Moléculaire UPR 3404, CNRS, Université Paris-Sud, FRC3115 1 Ave de la Terrasse, 91190 Gif-sur-Yvette, France.
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Chumbimuni-Torres KY, Coronado RE, Mfuh AM, Castro-Guerrero C, Silva MF, Negrete GR, Bizios R, Garcia CD. Adsorption of Proteins to Thin-Films of PDMS and Its Effect on the Adhesion of Human Endothelial Cells. RSC Adv 2011; 1:706-714. [PMID: 25068038 DOI: 10.1039/c1ra00198a] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This paper describes a simple and inexpensive procedure to produce thin-films of poly(dimethylsiloxane). Such films were characterized by a variety of techniques (ellipsometry, nuclear magnetic resonance, atomic force microscopy, and goniometry) and used to investigate the adsorption kinetics of three model proteins (fibrinogen, collagen type-I, and bovine serum albumin) under different conditions. The information collected from the protein adsorption studies was then used to investigate the adhesion of human dermal microvascular endothelial cells. The results of these studies suggest that these films can be used to model the surface properties of microdevices fabricated with commercial PDMS. Moreover, the paper provides guidelines to efficiently attach cells in BioMEMS devices.
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Affiliation(s)
| | - Ramon E Coronado
- Department of Biomedical Engineering, The University of Texas at San Antonio
| | - Adelphe M Mfuh
- Department of Chemistry, The University of Texas at San Antonio
| | | | - Maria Fernanda Silva
- School of Agronomic Sciences - IBAM-CONICET, National University of Cuyo, Mendoza, Argentina
| | | | - Rena Bizios
- Department of Biomedical Engineering, The University of Texas at San Antonio
| | - Carlos D Garcia
- Department of Chemistry, The University of Texas at San Antonio
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Srivastava SK, Gencoglu A, Minerick AR. DC insulator dielectrophoretic applications in microdevice technology: a review. Anal Bioanal Chem 2010; 399:301-21. [DOI: 10.1007/s00216-010-4222-6] [Citation(s) in RCA: 157] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 09/10/2010] [Accepted: 09/13/2010] [Indexed: 11/25/2022]
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Ye F, Shi M, Huang Y, Zhao S. Noncompetitive immunoassay for carcinoembryonic antigen in human serum by microchip electrophoresis for cancer diagnosis. Clin Chim Acta 2010; 411:1058-62. [DOI: 10.1016/j.cca.2010.03.035] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/24/2010] [Accepted: 03/24/2010] [Indexed: 02/04/2023]
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Affiliation(s)
- Richard N. Zare
- Department of Chemistry, Stanford University, Stanford, California 94305-5080;
| | - Samuel Kim
- Polymer Research Institute and National Core Research Center for Systems Bio-Dynamics, Pohang University of Science and Technology, Pohang, Kyungbuk, Korea;
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Tran NT, Ayed I, Pallandre A, Taverna M. Recent innovations in protein separation on microchips by electrophoretic methods: An update. Electrophoresis 2010; 31:147-73. [DOI: 10.1002/elps.200900465] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Single-Molecule Spectroscopy Using Microfluidic Platforms. Methods Enzymol 2010. [DOI: 10.1016/s0076-6879(10)72013-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Feng JJ, Wang AJ, Fan J, Xu JJ, Chen HY. Hydrophilic biopolymer grafted on poly(dimethylsiloxane) surface for microchip electrophoresis. Anal Chim Acta 2009; 658:75-80. [PMID: 20082777 DOI: 10.1016/j.aca.2009.10.052] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 09/19/2009] [Accepted: 10/21/2009] [Indexed: 11/29/2022]
Abstract
A novel covalent strategy was developed to modify the poly(dimethylsiloxane) (PDMS) surface. Briefly, dextran was selectively oxidized to aldehyde groups with sodium periodate and subsequently grafted onto amine-functionalized PDMS surface via Schiff base reaction. As expected, the coated PDMS surface efficiently prevented the biomolecules from adsorption. Electro-osmotic flow (EOF) was successfully suppressed compared with that on the native PDMS microchip. Moreover, the stability of EOF was greatly enhanced and the hydrophilicity of PDMS surface was also improved. To apply thus-coated microchip, the separation of peptides, protein and neurotransmitters was investigated in detail. For comparison, these analytes were also measured on the native PDMS microchips. The results demonstrated that these analytes were efficiently separated and detected on the coated PDMS microchips. Furthermore, the relative standard deviations of their migration times for run-to-run, day-to-day, and chip-to-chip reproducibilities were in the range of 0.6-2.7%. In addition, the coated PDMS microchips showed good stability within 1 month.
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Affiliation(s)
- Jiu-Ju Feng
- School of Chemistry and Environmental Science, Henan Key Laboratory for Environmental Pollution Control, Henan Normal University, Jianshe Road, Xinxiang, Henan 453007, China
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Klasner SA, Metto EC, Roman GT, Culbertson CT. Synthesis and characterization of a poly(dimethylsiloxane)-poly(ethylene oxide) block copolymer for fabrication of amphiphilic surfaces on microfluidic devices. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:10390-10396. [PMID: 19572528 DOI: 10.1021/la900920q] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A poly(dimethylsiloxane)-poly(ethylene oxide) (PDMS-PEO) vinyl terminated block copolymer has been synthesized via a simple hydrosilylation reaction between hydride-terminated PDMS and PEO divinyl ether. This prepolymer can be subsequently cross-linked into an elastomer in a second hydrosilylation reaction involving a methylhydrosiloxane-dimethylsiloxane copolymer, forming a material suitable for the purposes of fabricating microfluidic devices. The presence of the PEO block in the prepolymer chain results in a much more hydrophilic material following cross-linking. The surface water contact angle of the PDMS-PEO material is 65 degrees +/- 3 (n = 6), as opposed to approximately 110 degrees for native PDMS. Droplets of water straddled by air within molded channels of the PDMS-PEO are concave in shape with contact angles where the fluid meets the side walls of 32 degrees +/- 4 (n = 8), while droplets in PDMS microchannels are more convex with contact angles of 95 degrees +/- 6 (n = 6). The length of the PDMS-PEO prepolymer chain and the multifunctional hydride cross-linker chains appear to dictate the durability of the elastomeric material. Young's modulus measurements yielded values of 0.94 +/- 0.08, 2.6 +/- 0.8, and 1.91 +/- 0.06 MPa for a [5% vinyl excess prepolymer and 10-fold excess of cross-linker], [10% vinyl excess prepolymer and 5-fold excess of cross-linker], and 10:1 PDMS, respectively, confirming that the elasticity of the cross-linked PDMS-PEO is similar to that of PDMS (Sylgard 184:10:1 mixture of elastomeric base to elastomer curing agent). The PDMS-PEO material still possesses enough PDMS character to allow molded channel architectures to be sealed between two pieces of the block copolymer by conformal contact. As a result of the more hydrophilic nature of the material, the channels of devices fabricated from this polymer are self-filling when using aqueous buffers, making it more user-friendly than PDMS for applications calling for background electrolytes void of organic modifiers. Different compositions of PDMS-PEO devices feature different electroosmotic flow values with the 5% vinyl excess prepolymer EOF values of 2.5 +/- 0.7 x 10(-4) and 5.7 +/- 0.8 x 10(-4) cm(2)/(V s) at pHs 6 and 9, respectively, and 1.2 +/- 0.3 x 10(-4) and 2.5 +/- 0.3 x 10(-4) cm(2)/(V s) for the 10% vinyl excess prepolymer device at pHs 6 and 9, respectively.
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Affiliation(s)
- Scott A Klasner
- Department of Chemistry, Kansas State University, 111 Willard Hall, Manhattan, Kansas 66506, USA
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Zhou J, Yan H, Ren K, Dai W, Wu H. Convenient Method for Modifying Poly(dimethylsiloxane) with Poly(ethylene glycol) in Microfluidics. Anal Chem 2009; 81:6627-32. [DOI: 10.1021/ac900551m] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jianhua Zhou
- Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Hui Yan
- Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Kangning Ren
- Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Wen Dai
- Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Hongkai Wu
- Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Wang AJ, Feng JJ, Fan J. Covalent modified hydrophilic polymer brushes onto poly(dimethylsiloxane) microchannel surface for electrophoresis separation of amino acids. J Chromatogr A 2008; 1192:173-9. [PMID: 18384795 DOI: 10.1016/j.chroma.2008.03.038] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Revised: 03/08/2008] [Accepted: 03/12/2008] [Indexed: 11/24/2022]
Abstract
A new environmentally friendly method is developed for preventing nonspecific biomolecules from adsorption on poly(dimethylsiloxane) (PDMS) surface via in situ covalent modification. o-[(N-Succinimdyl)succiny]-o'-methyl-poly(ethylene glycol) (NSS-mPEG) was covalently grafted onto PDMS microchannel surface that was pretreated by air-plasma and silanized with 3-aminopropyl-triethoxysilanes (APTES). The modification processes were carried out in aqueous solution without any organic solvent. The mPEG side chains displayed extended structure and created a nonionic hydrophilic polymer brushes layer on PDMS surface, which can effectively prevent the adsorption of biomolecules. The developed method had improved reproducibility of separation and stability of electroosmotic flow (EOF), enhanced hydrophilicity of surface and peak resolution, and decreased adsorption of biomolecules. EOF in the modified microchannel was strongly suppressed, compared with those in the native and silanized PDMS microchips. Seven amino acids have been efficiently separated and successfully detected on the coated PDMS microchip coupled with end-channel amperometric detection. Relative standard deviations (RSDs) of their migration time for run-to-run, day-to-day and chip-to-chip, were all below 2.3%. Moreover, the covalent-modified PDMS channels displayed long-term stability for 4 weeks. This novel coating strategy showed promising application in biomolecules separation.
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Affiliation(s)
- Ai-Jun Wang
- School of Chemistry and Environmental Science, Henan Key Laboratory for Environmental Pollution Control, Henan Normal University, Xinxiang, Henan 453007, China.
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