Highly sensitive spectroscopic detection of heme-protein submonolayer films by channel integrated optical waveguide

Ismail Emre Araci, Sergio B. Mendes, Nasuhi Yurt, Seppo Honkanen, N. Peyghambarian

Research output: Contribution to journalArticle

19 Scopus citations


A highly sensitive technique based on optical absorption using a single-mode, channel integrated optical waveguide is described for broad spectral band detection and analysis of heme-containing protein films at a glass/water interface. Fabrication steps and device characteristics of optical waveguides suitable for operation in the wavelength range of 400 - 650 nm are described. Experimental results reported here show a limit of detection smaller than 100 pg/cm2 for a submonolayer of ferricytochrome c by probing the Soret transition band with a 406-nm semiconductor diode laser propagating in a single-mode, ion-exchanged channel waveguide. By taking advantage of the exceptionally low limit of detection, we examined the adsorption isotherm of cytochrome c on a glass surface with unprecedented detail. Unlike other surface-specific techniques (e.g. SPR, integrated optic Mach-Zehnder interferometer) that probe local refractive-index changes and therefore are very susceptible to temperature fluctuations, the integrated optical waveguide absorption technique probes molecular-specific transition bands and is expected to be less vulnerable to environmental perturbations.

Original languageEnglish (US)
Pages (from-to)5595-5603
Number of pages9
JournalOptics Express
Issue number9
StatePublished - Apr 30 2007


ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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