title: In vitro and in vivo biolasing of fluorescent proteins suspended in liquid microdroplet cavities.
abstract: Fluorescent proteins are indispensable for selective, quantitative visualization of localization, dynamics, and interactions of key molecular constituents of live cells. Incorporation of fluorescent proteins into an optical cavity can lead to a significant increase in fluorescence signal levels due to stimulated emission and light amplification in the cavity, forming a laser with biological gain medium. Utilization of lasing emission from fluorescent biological molecules can then greatly enhance the performance of fluorescence-based biosensors benefiting from the high sensitivity of non-linear lasing processes to small perturbations in the cavity and the gain medium. Here we study optofluidic biolasers that exploit active liquid optical resonators formed by surface-supported aqueous microdroplets containing purified yellow fluorescent protein or a suspension of live E. coli bacterial cells expressing the fluorescent protein. We first demonstrate lasing in fluorescent protein solutions at concentrations as low as 49 μM. Subsequently, we show that a single fluorescent bacterial cell of micrometre size confined in a droplet-based cavity can serve as a laser gain medium. Aqueous droplet microcavities allow the maintenance of the bacterial cells under conditions compatible with unimpeded growth. Therefore, our results also suggest a direct route to microscopic sources of laser light with self-regenerating gain media.
authors: Department of Physics, Istanbul Technical University, Maslak 34469, Istanbul, Turkey. ajonas@itu.edu.tr.
authors: Alexandr
authors: A
authors: Jonáš
authors: Mehdi
authors: M
authors: Aas
authors: Yasin
authors: Y
authors: Karadag
authors: Selen
authors: S
authors: Manioğlu
authors: Suman
authors: S
authors: Anand
authors: David
authors: D
authors: McGloin
authors: Halil
authors: H
authors: Bayraktar
authors: Alper
authors: A
authors: Kiraz
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism; D008164:Luminescent Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D013057:Spectrum Analysis
chemical_list: D001426:Bacterial Proteins; D008164:Luminescent Proteins; C054562:yellow fluorescent protein, Bacteria