Multicolor fluorescence enhancement from a photonics crystal surface

Abstract

A photonic crystal substrate exhibiting resonant enhancement of multiple fluorophores has been demonstrated. The device, fabricated uniformly from plastic materials over a ∼3×5 in.(2) surface area by nanoreplica molding, utilizes two distinct resonant modes to enhance electric field stimulation of a dye excited by a λ=632.8 nm laser (cyanine-5) and a dye excited by a λ=532 nm laser (cyanine-3). Resonant coupling of the laser excitation to the photonic crystal surface is obtained for each wavelength at a distinct incident angle. Compared to detection of a dye-labeled protein on an ordinary glass surface, the photonic crystal surface exhibited a 32× increase in fluorescent signal intensity for cyanine-5 conjugated streptavidin labeling, while a 25× increase was obtained for cyanine-3 conjugated streptavidin labeling. The photonic crystal is capable of amplifying the output of any fluorescent dye with an excitation wavelength in the 532 nm<λ<633 nm range by selection of an appropriate incident angle. The device is designed for biological assays that utilize multiple fluorescent dyes within a single imaged area, such as gene expression microarrays.

Photonic crystal enhanced fluorescence using a quartz substrate to reduce limits of detection

“…It is well known that plastic materials show significant autofluorescence when excited by near-UV or even visible radiation [30–32], with autofluorescence increasing as the illumination source photon energy is increased. This phenomena was demonstrated clearly in a recent publication, in which a PCEF surface designed for multiple excitation wavelengths (λ = 532 - 633 nm) showed best signal-to-noise sensitivity performance for longer excitation wavelengths, however the detection limit for short excitation wavelengths was limited by substrate autofluorescence [33]. Meanwhile, a great deal of research activity is directed towards developing new plastic substrates with lower autofluorescence [34–36].…”

Enhanced live cell imaging via photonic crystal enhanced fluorescence microscopy

“…In this work, the PC was intentionally designed to interact efficiently with a laser in the red part of the optical spectrum (λ = 637 nm), which coincides with the excitation wavelength of fluorophores for labelling cell structures. The approach described here may be extended to any other wavelength from UV 36 to IR 37 by selection of the PC period, and we have demonstrated that a single PC may be used to excite fluorophores with multiple excitation wavelengths 38 . The PCs used for all experiments reported here have a grating period of Λ = 400 nm, depth of d = 50 nm, and duty cycle of f = 50%.…”

Recent Advances in Biosensing With Photonic Crystal Surfaces: A Review

“…The “PC enhanced extraction” effect operates independently of the PC enhanced excitation effect, and thus their contributions multiply, resulting in the ability to achieve overall PC enhanced fluorescence [65–67] (PCEF) effects as high as 7500× [17, 68, 69]. PCEF has been applied to boost the signal-to-noise ratio for fluorescent dye molecules [65, 70–72], quantum dots [65, 67], and Raman scattering [73–75] for applications in biosensing and high efficiency lighting [76, 77].…”