Angularly resolved ellipsometric optical biosensing by means of Bloch surface waves

• Published in: Analytical and bioanalytical chemistry 2015-05, Vol.407 (14), p.3965-3974
• Main Authors: Sinibaldi, Alberto, Anopchenko, Aleksei, Rizzo, Riccardo, Danz, Norbert, Munzert, Peter, Rivolo, Paola, Frascella, Francesca, Ricciardi, Serena, Michelotti, Francesco
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Angiopoietin-2 - chemistry; Angiopoietin-2 - immunology; Animals; Antibodies; Biochemistry; Biomarkers; Biomarkers, Tumor; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Biosensors; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Crystals; Direct Optical Detection; Food Science; Glycoproteins; Humans; Laboratory Medicine; Lasers; Mice; Monitoring/Environmental Analysis; Optical Imaging - instrumentation; Optical Imaging - methods; Optical instruments; Optics; Optics and Photonics; Plasma etching; Recombinant Proteins - chemistry; Recombinant Proteins - immunology; Refractometry; Research Paper; Sensors; Silica; Spectrum analysis
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-015-8591-8

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 × 10 −7  refractive index units (RIU)/Hz 1/2 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. Graphical Abstract Camera image showing the resonance associated to the excitation of a Bloch surface wave in the two different regions of a biochip