title: Long-period gratings in photonic crystal fiber as an optofluidic label-free biosensor.
abstract: Using long-period gratings (LPG) inscribed in photonic crystal fiber (PCF) and coupling this structure with an optically aligned flow cell, we have developed an optofluidic refractive index transduction platform for label-free biosensing. The LPG-PCF scheme possesses extremely high sensitivity to the change in refractive index induced by localized binding event in different solution media. A model immunoassay experiment was carried out inside the air channels of PCF by a series of surface modification steps in sequence that include adsorption of poly(allylamine hydrochloride) monolayer, immobilization of anti-rat bone sialoprotein monoclonal primary antibody, and binding interactions with non-specific goat anti-rabbit IgG (H+L) and specific secondary goat anti-mouse IgG (H+L) antibodies. These adsorption and binding events were monitored in situ using the LPG-PCF by measuring the shift of the core-to-cladding mode coupling resonance wavelength. Steady and significant resonance changes, about 0.75 nm per nanometer-thick adsorbed/bound bio-molecules, have been observed following the sequence of the surface events with monolayer sensitivity, suggesting the promising potential of LPG-PCF for biological sensing and evaluation.
authors.affiliation: Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
authors.forename: Zonghu
authors.initials: Z
authors.lastname: He
authors.forename: Fei
authors.initials: F
authors.lastname: Tian
authors.forename: Yinian
authors.initials: Y
authors.lastname: Zhu
authors.forename: Nina
authors.initials: N
authors.lastname: Lavlinskaia
authors.forename: Henry
authors.initials: H
authors.lastname: Du
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized / Q000737:chemistry / Q000276:immunology*; D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D007118:Immunoassay / Q000295:instrumentation; D058574:Integrin-Binding Sialoprotein / Q000276:immunology*; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D055095:Optics and Photonics / Q000295:instrumentation*; D011817:Rabbits; D051381:Rats; D012031:Refractometry; D012680:Sensitivity and Specificity
chemical_list: D055910:Antibodies, Immobilized; D058574:Integrin-Binding Sialoprotein