title: Optical biosensor based on hollow integrated waveguides.
abstract: The first absorbance biosensor based on pure silicon hollow integrated waveguides is presented in this work. With the use of horseradish peroxidase (HRP) as a model recognition element, an enzymatic sensor for the measurement of hydrogen peroxide was fabricated, numerically simulated, and experimentally characterized. Waveguides with widths ranging from 50 to 80 microm, having a depth of 50 microm and lengths up to 5 mm were easily fabricated by just one photolithographic step. These were further modified by covalent immobilization of HRP using silanization chemistry. Simulation studies of the proposed approach showed a sensor linear behavior up to 300 microM H2O2 and a sensitivity of 2.7 x 10(-3) AU/microM. Experimental results were in good agreement with the simulated ones. A linear behavior between 10 and 300 microM H2O2, a sensitivity of 3 x 10(-3) AU/microM, and a signal-to-noise ratio around 20 dB were attained. Also, kinetic studies of the activity of the immobilized enzyme on the silicon waveguide surface gave an apparent Michaelis-Menten constant of 0.44 mM. The simple technology proposed in this work enables the fabrication of cost-effective, easy-to-use, miniaturized biosensor generic platforms, these being envisioned as excellent candidates for the development of lab-on-a-chip systems.
authors.affiliation: Institut de Microelectronica de Barcelona, CNM-IMB, CSIC, Campus UAB 08193 Barcelona, Spain.
authors.forename: Víctor J
authors.initials: VJ
authors.lastname: Cadarso
authors.forename: César
authors.initials: C
authors.lastname: Fernández-Sánchez
authors.forename: Andreu
authors.initials: A
authors.lastname: Llobera
authors.forename: Margarita
authors.initials: M
authors.lastname: Darder
authors.forename: Carlos
authors.initials: C
authors.lastname: Domínguez
mesh_terms: D052160:Benzothiazoles / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D004800:Enzymes, Immobilized / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000032:analysis; D007700:Kinetics; D046210:Microfluidic Analytical Techniques / Q000379:methods; D055095:Optics and Photonics; D012825:Silicon / Q000737:chemistry*; D013451:Sulfonic Acids / Q000737:chemistry
chemical_list: D052160:Benzothiazoles; D004800:Enzymes, Immobilized; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D012825:Silicon