Long Range Surface Plasmons for Observation of Biomolecular Binding Events at Metallic Surfaces
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A long range surface plasmon (LRSP) is an electromagnetic wave propagating along a thin metal film with an order of magnitude lower damping than conventional surface plasmon (SP) waves. Thus, the excitation of LRSP is associated with a narrower resonance and it provides larger enhancement of intensity of the electromagnetic field. In surface plasmon resonance (SPR) biosensors, these features allow a more precise observation of the binding of biomolecules in the proximity to the metal surface by using the (label-free) measurement of refractive index (RI) variations and by SP-enhanced fluorescence spectroscopy. In this contribution, we investigate LRSPs excited on a layer structure consisting of a fluoropolymer buffer layer, a thin gold film, and an aqueous sample. By implementing such structure in an SPR sensor, we achieved a 2.4- and 4.4-fold improvement of the resolution in the label-free and fluorescence-based detection, respectively, of the binding of biomolecules in the close proximity to the surface. Moreover, we demonstrate that the sensor resolution can be improved by a factor of 14 and 12 for the label-free and fluorescence-based detection, respectively, if the biomolecular binding events occur within the whole evanescent field of LRSP.
KeywordsSurface plasmon resonance Long range surface plasmon Biosensor Fluorescence spectroscopy Optical sensor
Partial support for this work was provided by the Deutsche Forschungsgemainschaft (KN 224/18-1, Schwerpunktprogramm “Intelligente Hydrogele”, JPP 1259) and by the EU through FP6-2005-FOOD-036300 (“TRACEPACK”).
- 1.Rather H (1983) Surface plasmons on smooth and rough surfaces and on gratings. Springer, Berlin Heidelberg New YorkGoogle Scholar
- 5.Craig AE, Olson GA, Sarid D (1983) Experimental observation of the long-range surface-plasmon polariton. Opt Lett 8:380–382Google Scholar
- 8.Slavik S, Homola J (2007) Ultrahigh resolution long range surface plasmon-based sensor. Sens Actuators, B, Chem 123:10–12Google Scholar
- 12.Swann MJ, Peel LL, Carrington S, Freeman NJ (2004) Dual-polarization interferometry: an analytical technique to measure changes in protein structure in real time, to determine the stoichiometry of binding events, and to differentiate between specific and nonspecific interactions. Anal Biochem 329:190–198CrossRefGoogle Scholar