title: Optimization of DNA-directed immobilization on mixed oligo(ethylene glycol) monolayers for immunodetection.
abstract: The development of protein chips has suffered from problems regarding long-term protein stability and activity. We present a protein sensor surface for immunodetection that is prepared by a DNA-directed protein immobilization method on a mixed self-assembled monolayer (SAM). By this approach, an immobilized single-stranded DNA (ssDNA) surface can be transferred/modified into a protein chip by flowing in ssDNA-conjugated protein when the protein chip measurement is needed. Therefore, the long-term stability of the protein chip will not be a problem for various applications. We tried various compositions for the SAM layer, the length of the ssDNA spacer, the end-point nucleotide composition, and the processes of ssDNA immobilization of the SAM for an optimized condition for shifting the DNA chip to a protein chip. The evaluations were made by using surface plasmon resonance. Our results indicated that a 50:1 ratio of oligo(ethylene glycol) (OEG)/COOH-terminated OEG and DNA sequences with 20mer are the best conditions found here for making a protein chip via a DNA-directed immobilization (DDI) method. The designed end-point nucleotide composition contains a few guanines or cytosines, and ssDNA immobilization of the SAM by dehybridizing immobilized double-stranded DNA (dsDNA) can improve the hybridization efficiency.
authors.affiliation: Department of Biomedical Informatics, Asia University, Taichung 41354, Taiwan.
authors.forename: Wen-Pin
authors.initials: WP
authors.lastname: Hu
authors.forename: Li-Ya
authors.initials: LY
authors.lastname: Huang
authors.forename: Tai-Chih
authors.initials: TC
authors.lastname: Kuo
authors.forename: Wei-Wen
authors.initials: WW
authors.lastname: Hu
authors.forename: Yung
authors.initials: Y
authors.lastname: Chang
authors.forename: Chien-Sheng
authors.initials: CS
authors.lastname: Chen
authors.forename: Hong-Cheng
authors.initials: HC
authors.lastname: Chen
authors.forename: Wen-Yih
authors.initials: WY
authors.lastname: Chen
mesh_terms: D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D001483:Base Sequence; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000378:metabolism; D019855:Ethylene Glycol / Q000737:chemistry*; D007118:Immunoassay / Q000379:methods*; D009113:Muramidase / Q000032:analysis / Q000276:immunology; D040081:Protein Array Analysis; D011506:Proteins / Q000032:analysis* / Q000276:immunology; D012709:Serum Albumin / Q000032:analysis / Q000276:immunology; D020349:Surface Plasmon Resonance
chemical_list: D000906:Antibodies; D004277:DNA, Single-Stranded; D011506:Proteins; D012709:Serum Albumin; D009113:Muramidase; D019855:Ethylene Glycol