title: Characterisation of morphology of self-assembled PEG monolayers: a comparison of mixed and pure coatings optimised for biosensor applications.
abstract: For detection of low concentrations of analytes in complex biological matrices using optical biosensors, a high surface loading with capture molecules and a low nonspecific binding of nonrelevant matrix molecules are essential. To tailor biosensor surfaces in such a manner, poly(ethylene glycols) (PEG) in varying lengths were immobilised covalently onto glass-type surfaces in different mixing ratios and concentrations, and were subsequently modified with three different kinds of receptors. The nonspecific binding of a model protein (ovalbumin, OVA) and the maximum loading of the respective analytes to these prepared surfaces were monitored using label-free and time-resolved reflectometric interference spectroscopy (RIfS). The three different analytes used varied in size: 150 kDa for the anti-atrazine antibody, 60 kDa for streptavidin and 5 kDa for the 15-bp oligonucleotide. We investigated if the mixing of PEG in different lengths could increase the surface loadings of analyte mimicking a three-dimensional matrix as was found using dextrans as sensor coatings. In addition, the effect on the surface loading was investigated with regard to the size of the analyte molecule using such mixed PEGs on the sensor surface. For further characterisation of the surface coatings, polarisation modulation infrared reflection absorption spectroscopy, atomic force microscopy, and ellipsometry were applied.
authors.affiliation: Institute of Physical and Theoretical Chemistry (IPTC), Eberhard-Karls-University of Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Mehne
authors.forename: Goran
authors.initials: G
authors.lastname: Markovic
authors.forename: Florian
authors.initials: F
authors.lastname: Pröll
authors.forename: Nina
authors.initials: N
authors.lastname: Schweizer
authors.forename: Stefan
authors.initials: S
authors.lastname: Zorn
authors.forename: Frank
authors.initials: F
authors.lastname: Schreiber
authors.forename: Günter
authors.initials: G
authors.lastname: Gauglitz
mesh_terms: D000327:Adsorption; D000906:Antibodies; D001280:Atrazine / Q000032:analysis / Q000737:chemistry / Q000276:immunology; D001665:Binding Sites; D015374:Biosensing Techniques / Q000379:methods*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry*; D005898:Glass / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008970:Molecular Weight; D009841:Oligonucleotides / Q000032:analysis / Q000737:chemistry; D010047:Ovalbumin / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000379:methods*; D019809:Streptavidin / Q000032:analysis / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000906:Antibodies; D020099:Coated Materials, Biocompatible; D003911:Dextrans; D009841:Oligonucleotides; D011092:Polyethylene Glycols; D010047:Ovalbumin; D019809:Streptavidin; D001280:Atrazine