title: Hydrogel with chains functionalized with carboxyl groups as universal 3D platform in DNA biosensors.
abstract: Application of hydrogel based on N-isopropylacrylamide with carboxyl groups grafted to the chains enabled the immobilization of DNA at an extent exceeding that for flat surfaces by at least one order of magnitude. The probe DNA strands in the 3D platform were fully available for the hybridization process. The examination of the gels containing different amounts of grafted carboxyl groups (1-10%) was done using quartz crystal microbalance, electrochemical impedance spectroscopy, chronoamperometry and ionic coupled plasma with laser ablation. The optimal carboxyl group content was determined to be 5%. A very good agreement of the data obtained with independent techniques on content of DNA in the gel was obtained. In comparison to the other methods of immobilization of DNA the new platform enabled complete removal of DNA after the measurements and analysis and, therefore, could be used many times. After a 10-fold exchange of the DNA-sensing layer the efficiency of hybridization and analytical signal did not change by more than 5%. The sensor response increased linearly with logarithm of concentration of target DNA in the range 1×10(-13)-1×10(-6) M. The obtained detection limit was circa 8×10(-13) M of target DNA in the sample which is a substantial improvement over the planar sensing layers.
authors.affiliation: Faculty of Chemistry, University of Warsaw, Ul. Pasteura 1, 02-093 Warsaw, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Kowalczyk
authors.affiliation: Faculty of Chemistry, University of Warsaw, Ul. Pasteura 1, 02-093 Warsaw, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Fau
authors.affiliation: Faculty of Chemistry, University of Warsaw, Ul. Pasteura 1, 02-093 Warsaw, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Karbarz
authors.affiliation: Faculty of Chemistry, University of Warsaw, Ul. Pasteura 1, 02-093 Warsaw, Poland.
authors.forename: Mikolaj
authors.initials: M
authors.lastname: Donten
authors.affiliation: Faculty of Chemistry, University of Warsaw, Ul. Pasteura 1, 02-093 Warsaw, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Stojek
authors.affiliation: Faculty of Chemistry, University of Warsaw, Ul. Pasteura 1, 02-093 Warsaw, Poland. Electronic address: anowicka@chem.uw.edu.pl.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Nowicka
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002264:Carboxylic Acids / Q000737:chemistry; D004247:DNA / Q000032:analysis*; D015342:DNA Probes / Q000737:chemistry; D058266:Dielectric Spectroscopy / Q000379:methods; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D057230:Limit of Detection; D009693:Nucleic Acid Hybridization / Q000379:methods; D058525:Quartz Crystal Microbalance Techniques / Q000379:methods
chemical_list: D000178:Acrylamides; D002264:Carboxylic Acids; D015342:DNA Probes; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D004247:DNA; C067295:N-isopropylacrylamide
keywords: DNA biosensor; Electrochemical impedance spectroscopy; Electrochemical quartz crystal microbalance; Hydrogel; Scanning electron microscopy