Intracavity enhancement of GFP fluorescence induced by femtosecond laser pulses

The phenomenon of fluorescence is widely used in molecular biology for studying the interaction of light with biological objects. In this article, we present an experimental investigation of the enhancement of laser-induced fluorescence of Clytia gregaria green fluorescent protein. The laser-induced fluorescence method applied in our work combines the advantages of femtosecond laser pulses and a photonic crystal cavity, with the time dependence of the fluorescence signal studied. It is shown that a green fluorescent protein solution placed in a microcavity and excited by femtosecond laser pulses leads to an increase in fluorescence on the microcavity modes, which can be estimated by two orders of magnitude. The dependences of fluorescence signal saturation on the average integrated optical pump power are demonstrated and analyzed. The results obtained are of interest for the development of potential applications of biophotonics and extension of convenient methods of laser-induced fluorescence. [Display omitted] •GFP provides high biocompatibility and bioabsorbability.•Laser-induced fluorescence allows decreasing the detection limit of bioassays.•Use of photonic crystal microcavity leads to fluorescence enhancement.•Femtosecond pulses avoid thermal effects and preserve the viability of biosamples.•Combining these approaches expands traditional methods of laser-induced fluorescence.