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Angularly resolved ellipsometric optical biosensing by means of Bloch surface waves

: Sinibaldi, A.; Anopchenko, A.; Rizzo, R.; Danz, N.; Munzert, P.; Rivolo, P.; Frascella, F.; Ricciardi, S.; Michelotti, F.


Analytical and bioanalytical chemistry 407 (2015), No.14, pp.3965-3974
ISSN: 1618-2642 (Print)
ISSN: 1618-2650 (Online)
Journal Article
Fraunhofer IOF ()

In label-free biosensing, a continuous improvement of the limit of detection is necessary to resolve the small change of the surface refractive index produced by interacting biomolecules at a very small concentration. In the present work, optical sensors based on one-dimensional photonic crystals supporting Bloch surface waves are proposed and adopted for label-free optical biosensing. We describe the implementation of an angularly resolved ellipsometric optical sensing scheme based on Bloch surface waves sustained by tantala/silica multilayers. The angular operation is obtained using a focused beam at fixed wavelength and detection of the angular reflectance spectrum by means of an array detector. The results show that the experimental limit of detection for a particular photonic crystal design is 6.5 × 107 refractive index units (RIU)/Hz1/2 and further decrease could be obtained. For the first time, we report on the practical application of this technique to a cancer biomarker protocol that aims at the detection of a specific glycoprotein (angiopoietin 2) involved in angiogenesis and inflammation processes.