title: Smart detection of microRNAs through fluorescence enhancement on a photonic crystal.
abstract: The detection of low abundant biomarkers, such as circulating microRNAs, demands innovative detection methods with increased resolution, sensitivity and specificity. Here, a biofunctional surface was implemented for the selective capture of microRNAs, which were detected through fluorescence enhancement directly on a photonic crystal. To set up the optimal biofunctional surface, epoxy-coated commercially available microscope slides were spotted with specific anti-microRNA probes. The optimal concentration of probe as well as of passivating agent were selected and employed for titrating the microRNA hybridization. Cross-hybridization of different microRNAs was also tested, resulting negligible. Once optimized, the protocol was adapted to the photonic crystal surface, where fluorescent synthetic miR-16 was hybridized and imaged with a dedicated equipment. The photonic crystal consists of a dielectric multilayer patterned with a grating structure. In this way, it is possible to take advantage from both a resonant excitation of fluorophores and an angularly redirection of the emitted radiation. As a result, a significant fluorescence enhancement due to the resonant structure is collected from the patterned photonic crystal with respect to the outer non-structured surface. The dedicated read-out system is compact and based on a wide-field imaging detection, with little or no optical alignment issues, which makes this approach particularly interesting for further development such as for example in microarray-type bioassays.
authors.affiliation: FBK - Fondazione Bruno Kessler, Laboratory of Biomolecular Sequence and Structure Analysis for Health, via Sommarive 18, I-38123 Povo (Trento), Italy.
authors.forename: L
authors.initials: L
authors.lastname: Pasquardini
authors.affiliation: FBK - Fondazione Bruno Kessler, Laboratory of Biomolecular Sequence and Structure Analysis for Health, via Sommarive 18, I-38123 Povo (Trento), Italy; CNR - Consiglio Nazionale delle Ricerche, Istituto di Biofisica, via alla Cascata 56/C, I-38123 Povo (Trento), Italy. Electronic address: cpotrich@fbk.eu.
authors.forename: C
authors.initials: C
authors.lastname: Potrich
authors.affiliation: FBK - Fondazione Bruno Kessler, Laboratory of Biomolecular Sequence and Structure Analysis for Health, via Sommarive 18, I-38123 Povo (Trento), Italy.
authors.forename: V
authors.initials: V
authors.lastname: Vaghi
authors.affiliation: FBK - Fondazione Bruno Kessler, Laboratory of Biomolecular Sequence and Structure Analysis for Health, via Sommarive 18, I-38123 Povo (Trento), Italy; CNR - Consiglio Nazionale delle Ricerche, Istituto di Biofisica, via alla Cascata 56/C, I-38123 Povo (Trento), Italy.
authors.forename: L
authors.initials: L
authors.lastname: Lunelli
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino I-10129, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Frascella
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino I-10129, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Descrovi
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino I-10129, Italy.
authors.forename: C F
authors.initials: CF
authors.lastname: Pirri
authors.affiliation: FBK - Fondazione Bruno Kessler, Laboratory of Biomolecular Sequence and Structure Analysis for Health, via Sommarive 18, I-38123 Povo (Trento), Italy.
authors.forename: C
authors.initials: C
authors.lastname: Pederzolli
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D005453:Fluorescence; D006801:Humans; D057230:Limit of Detection; D035683:MicroRNAs / Q000032:analysis* / Q000737:chemistry; D017785:Photons; D013050:Spectrometry, Fluorescence
chemical_list: D035683:MicroRNAs
keywords: Epoxy functionalization; Fluorescence enhancement; MicroRNA hybridization; Photonic crystal