Label-Free Detection of Tumor Angiogenesis Biomarker Angiopoietin 2 Using Bloch Surface Waves on One Dimensional Photonic Crystals

Alberto Sinibaldi, Norbert Danz, Aleksei Anopchenko, Peter Munzert, Stefan Schmieder, Rona Chandrawati, Riccardo Rizzo, Subinoy Rana, Frank Sonntag, Agostino Occhicone, Lucia Napione, Simone De Panfilis, Molly M. Stevens, Francesco Michelotti

Research output: Contribution to journalArticlepeer-review


We describe the design and fabrication of biochips based on 1-D photonic crystals supporting Bloch surface waves for label-free optical biosensing. The optical properties of Bloch surface waves are studied in relation to the geometry of the photonic crystals and on the properties of the dielectric materials used for the fabrication. The planar stacks of the biochips are composed of silica, tantala, and titania that were deposited using plasma-ion-assisted evaporation under high-vacuum conditions. The biochip surfaces were functionalized by silanization, and appropriate fluidic cells were designed to operate in an automated platform. An angularly resolved ellipsometric optical sensing apparatus was assembled to carry out the sensing studies. The angular operation is obtained by a focused laser beam at a fixed wavelength and detection of the angular reflectance spectrum by means of an array detector. The results of the experimental characterization of the physical properties of the fabricated biochips show that their characteristics, in terms of sensitivity and figure of merit, match those expected from the numerical simulations. Practical application of the sensor was demonstrated by detecting a specific glycoprotein, Angio-poietin 2, that is involved in angiogenesis and inflammation processes. The protocol used for the label-free detection of Angiopoietin 2 is described, and the results of an exemplary assay, carried out at a relatively high concentration of 1 μg/ml, are given and confirm that an efficient detection can be achieved. The limit of detection of the biochips for Angiopoietin 2, based on the protocol used, is 1.5 pg/mm2 in buffer solution. The efficiency of the label-free assay is confirmed by independent measurements carried out by means of confocal fluorescence microscopy.

Original languageEnglish
Article number7134707
Pages (from-to)3385-3393
Number of pages9
JournalJournal of Lightwave Technology
Issue number16
Publication statusPublished - Aug 15 2015


  • Angiopoietin 2
  • Bloch surface waves
  • ELFA
  • enzyme linked fluorescence assay
  • label-free optical sensors
  • Optical biosensors
  • optical multilayer systems
  • photonic crystal
  • Protein G

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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