Sensitive molecular binding assay using a photonic crystal structure in total internal reflection

Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI 48109-2099, USA.
Optics Express (Impact Factor: 3.49). 09/2008; 16(16):11741-9. DOI: 10.1364/OE.16.011741
Source: PubMed


A novel optical sensor for label-free biomolecular binding assay using a one-dimensional photonic crystal in a total-internal-reflection geometry is proposed and demonstrated. The simple configuration provides a narrow optical resonance to enable sensitive measurements of molecular binding, and at the same time employs an open interface to enable real-time measurements of binding dynamics. Ultrathin aminopropyltriethoxysilane/ glutaraldehyde films adsorbed on the interface were detected by measuring the spectral shift of the photonic crystal resonance and the intensity ratio change in a differential reflectance measurement. A detection limit of 6 x 10(-5) nm for molecular layer thickness was obtained, which corresponds to a detection limit for analyte adsorption of 0.06 pg/mm(2) or a refractive index resolution of 3 x 10(-8) RIU; this represents a significant improvement relative to state-of-the-art surface-plasmon-resonance-based systems.

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Available from: James R Baker, Dec 17, 2013
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    • "For coating as indicated in Figure 5(a), (i) the baseline was calibrated with PBS; (ii) the sensor was coated with fibronectin (200 μg/mL) and the coating was detected by measuring the resonant wavelength shift; (iii) the subsequent washes removed the unbound protein molecules, leading to a minor reduction in the resonance shift, but the substantial changes still remained indicating the effective coating of the sensor by fibronectin. The binding thickness of fibronectin on the sensor was determined to be 4.8 nm corresponding to the 4.2 nm resonance shift calculated with a transfer matrix method [31]. For protein binding as demonstrated in Figure 5(b) (blue), after (I) the coating baseline was calibrated, (II) EF-Tu was added onto the fibronectin-coated sensor surface. "
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