Surface Plasmon Resonance (SPR) has been used already for a few decades for label-free detection and characterization of biochemical kinetics and affinities of many different types of analytes. However, the physical phenomenon is not limited to biochemistry, but is applicable to other nanoscale characterization of thin films [1]. Multi-parametric surface plasmon resonance (MP-SPR) is a new approach to the physical phenomenon, which utilizes full SPR angular spectral measurement and allows also new type of thin film characterization methods to be used. MP-SPR can be used to characterize ultrathin nanoscale films for both thickness and refractive index with two methods. It is possible to characterize the films either by measuring them in two different media with high RI difference, such as air and water [1,2], or by measuring the films with two or more wavelengths of light [2,3]. The method effectiveness has been extensively demonstrated using diffetrent ultrathin films systems [2-4]. Stearic acid (SA) LB films showed approximately 2.5±0.2 nm thickness with both 2M and 3W methods, and linear increment with layer number. Similarly the polyelectrolyte multilayer of polystyrenesulfonate and polyallylaminehydrochloride (PSS:PAH) was characterized to grow in 3-3.5 nm steps per layer pair. Lipid bilayers spread from vesicles showed typical thickness of approximately 5 nm. The refractive index of all studied thin films correlated well to earlier literature values. Ex-situ depositions of nanofibrillated cellulose (NFC) by spin coating were characterized by the 2W method to form 14 ±3.4 nm layers. Thus the MP-SPR based characterization methods for ultrathin films appear to be effective, especially for applications requiring both measurement of the film properties and interactions of different compounds with the film. References [1]Albers, Vikholm-Lundin, Chapter4 in Nano-Bio-Sensing, Springer2010 [2]Granqvist et al., Langmuir 2013,29(27),2013,8561-8571 [3]Granqvist et al., Langmuir 2014,30(10),2799–2809 [4]Kontturi et al., J.Mater.Chem.A, 2013,1,13655-13663

Characterization of solid-supported ultrathin films and molecular interactions using MP-SPR

251st National Meeting (2016)

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