title: Prostate specific antigen biosensor based on long range surface plasmon-enhanced fluorescence spectroscopy and dextran hydrogel binding matrix.
abstract: A new biosensor based on surface plasmon-enhanced fluorescence spectroscopy (SPFS), which employs long-range surface plasmons (LRSP) and a photo-cross-linkable carboxymethyl dextran (PCDM) hydrogel binding matrix, is reported. LRSPs are surface plasmon modes that propagate along a thin metallic film with orders of magnitude lower damping compared to regular surface plasmons. Therefore, their excitation provides strong enhancement of the intensity of the electromagnetic field and a greatly increased fluorescence signal measured upon binding of fluorophore-labeled molecules on the sensor surface. In addition, these modes exhibit highly extended evanescent fields penetrating up to micrometers in distance from the metallic sensor surface. Therefore, a PCDM hydrogel with approximately micrometer thickness was anchored on the sensor surface to serve as the binding matrix. We show that this approach provides large binding capacity and allows for the ultrasensitive detection. In a model experiment, the developed biosensor platform was applied for the detection of free prostate specific antigen (f-PSA) in buffer and human serum by using a sandwich immunoassay. The limit of detection at the low femtomolar range was achieved, which is approximately 4 orders of magnitude lower than that for direct detection of f-PSA based on the monitoring of binding-induced refractive index changes.
authors.affiliation: Austrian Institute of Technology, Donau-City-Strasse 1, 1220 Vienna, Austria.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Annette
authors.initials: A
authors.lastname: Brunsen
authors.forename: Ulrich
authors.initials: U
authors.lastname: Jonas
authors.forename: Jakub
authors.initials: J
authors.lastname: Dostálek
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Knoll
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D003911:Dextrans / Q000737:chemistry* / Q000378:metabolism*; D004583:Electrons; D006801:Humans; D020100:Hydrogels; D007700:Kinetics; D051379:Mice; D017430:Prostate-Specific Antigen / Q000032:analysis* / Q000097:blood / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D003911:Dextrans; D020100:Hydrogels; C014392:carboxymethyl dextran; D017430:Prostate-Specific Antigen