Label free biosensor incorporating a replica-molded, vertically emitting distributed feedback laser

Abstract

A label free biosensor based upon a vertically emitting distributed feedback ͑DFB͒ laser has been demonstrated. The DFB laser comprises a replica-molded, one-dimensional dielectric grating coated with laser dye-doped polymer as the gain medium. Adsorption of biomolecules onto the laser surface alters the DFB laser emission wavelength, thereby permitting the kinetic adsorption of a protein polymer monolayer or the specific binding of small molecules to be quantified. A bulk sensitivity of 16.6 nm per refractive index unit and the detection of a monolayer of the protein polymer poly͑Lys, Phe͒ have been observed with this biosensor. The sensor represents a departure from conventional passive resonant optical sensors from the standpoint that the device actively generates its own narrowband high intensity output without stringent requirements on the coupling alignments, resulting in a simple, robust illumination and detection configuration.

Distributed feedback lasers based on perylenediimide dyes for label-free refractive index sensing

“…A wide variety of materials have been used to fabricate the active layers of DFB sensors: organic semiconductors prepared as neat films, such as truxene-core molecules [24] or semiconducting polymers [25]; or laser dyes dispersed in inert polymers, for example Rhodamine 590 in the SU-8 resist [19,26], Coumarin 503 in poly(methyl methacrylate) (PMMA) [16] or Pyrromethene 597 in Ormocore [21]. Among many families of laser dyes, pyrromethenes and perylenediimides (PDIs) are among the most photostable (independently on the type of matrix or device).…”

“…The second-order solid-state organic distributed feedback laser (DFB) [14,15] represents the next step from passive to active optical refractometric sensors, because the structure incorporates its own source of optical gain and feedback, so that it allows achieving narrow bandwidth output through the process of stimulated emission [16,17]. Although the linewidths achievable by DFB sensors are generally not narrower than those obtained with some of the sensors mentioned, they are simultaneously capable of high sensitivity and a high degree of resolution.…”

Organic distributed feedback laser for label-free biosensing of ErbB2 protein biomarker

“…Label-free resonant optical sensors generally detect shifts in the resonant wavelength caused by the interaction between the target molecule and the evanescent portion of resonant modes, and the amount of wavelength shift is proportional to the density of captured biomolecule on the sensor surface. The narrow spectral linewidth achieved by using quality factor (Q-factor) (>10 5 ) passive optical resonators enables sensor systems to resolve smaller wavelength shifts associated with the detection of analytes at low concentration, or biomolecules with low molecular weight, such as drug compounds [2,3]. While detection resolution can be substantially improved through the use of high M a n u s c r i p t Q-factor passive resonators, it is generally at a cost of a decrease of the sensitivity and the dynamic range of the system.…”

“…One way to solve this problem is to use organic distributed feedback (DFB) lasers. These laser biosensors are simultaneously capable of a high sensitivity and a high degree of resolution, since they operate with single mode and narrow linewidth emission [5][6][7]. A recently reported strategy to work with good figures of merit for both, resolution and sensitivity, consists in using a photonic crystal resonant reflection technique.…”

“…Sensitivities (S b ) in the biological range (at n = 1.33) of around 20 nm/RIU have been achieved with DFBs used for the detection of proteins [5,14]. Better sensitivities, of the order of 70-150 nm/RIU have been obtained by experiments and simulations [6,15] with DFB laser sensors coated with a thin layer of high refractive index of TiO 2 (n= 2.1).…”