title: Photonic crystal enhancement of a homogeneous fluorescent assay using submicron fluid channels fabricated by E-jet patterning.
abstract: We demonstrate the enhancement of a liquid-based homogenous fluorescence assay using the resonant electric fields from a photonic crystal (PC) surface. Because evanescent fields are confined to the liquid volume nearest to the photonic crystal, we developed a simple approach for integrating a PC fabricated on a silicon substrate within a fluid channel with submicron height, using electrohydrodynamic jet (e-jet) printing of a light-curable epoxy adhesive to define the fluid channel pattern. The PC is excited by a custom-designed compact instrument that illuminates the PC with collimated light that precisely matches the resonant coupling condition when the PC is covered with aqueous media. Using a molecular beacon nucleic acid fluorescence resonant energy transfer (FRET) probe for a specific miRNA sequence, we demonstrate an 8× enhancement of the fluorescence emission signal, compared to performing the same assay without exciting resonance in the PC detecting a miRNA sequence at a concentration of 62 nM from a liquid volume of only ∼20 nL. The approach may be utilized for any liquid-based fluorescence assay for applications in point-of-care diagnostics, environmental monitoring, or pathogen detection.
authors.affiliation: University of Illinois at Urbana Champaign - Department of Electrical and Computer Engineering, 1406 West Green Street, Urbana, Illinois, USA.
authors.forename: Yafang
authors.initials: Y
authors.lastname: Tan
authors.forename: Erick
authors.initials: E
authors.lastname: Sutanto
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Alleyne
authors.forename: Brian T
authors.initials: BT
authors.lastname: Cunningham
mesh_terms: D000269:Adhesives; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D003198:Computer Simulation; D003460:Crystallization; D004867:Equipment Design; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D008027:Light; D035683:MicroRNAs / Q000032:analysis*; D049329:Nanostructures / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods; D017785:Photons; D012031:Refractometry; D012825:Silicon / Q000737:chemistry
chemical_list: D000269:Adhesives; D035683:MicroRNAs; D012825:Silicon
keywords: E-jet printing; enhanced fluorescence; homogeneous assay; photonic crystal; submicron channel