ИСТИНА

The infiltration of fluorescent macromolecules into porous photonic materials is one of the hot topics that connects bioscience and nanophotonics. Porous photonic crystals (PCs) are promising materials allows us to control the light at the nanoscale and concentrate the light field to enhance a plenty of optical effects. In this work we chose a pair of visible fluorescent proteins (visFPs): enhanced green fluorescent protein (EGFP) and monomeric red fluorescent protein (TagRFP) - and infiltrated them into photonic crystals. EGFP and TagRFP belongs to the well-known group of proteins with chromophore buried inside a beta-barrel with diameter and height about 2.4 nm and 4.2 nm, respectively. We selected these substances because of two effects: on the one hand the emission spectrum of EGFP overlaps the absorption one of TagRFP that makes these visFPs a donor-acceptor pair with Foerster radius about 5.7 nm. On the other hand infiltration of this pair into photonic crystal may enhance the energy transfer rate compared with that in solution due to matching photonic band gap (PBG) and emission band of the donor. Here we synthesized a set of PCs via electrochemical etching of porous silicon and characterize its proreties. The PCs have 1000 layers with refractive indices of 1.32 and 1.45, spectral position of the PBG varies across the sample set in the visible range. The diameter of pores exceeds protein dimensions so the infiltration of the protein is successful. The concentration of the infiltrated protein is high enough for effective energy transfer. The wide variation of the PBG spectral position allows us to choose the suitable PC even if the photophysical properties of visFPs alters due to surrounding matrix. We compared the spectrum and intensity of emission of visFPs infiltrated into PC with free visFPs in solution and studied the influence of the surrounding porous matrix on photophysicsl properties of visFPs. We infiltrated two sets of PCs correspondingly with EGFP and TagRFP alone and in each set we chose samples where the emission is blocked by the PBG. The obtained results shed further light of investigation of photophysical properties of visFPs in PC. In further we plan to infiltrate both donor and acceptor visFP into one PC to verify the possibility of control of the energy transfer rate between biological macromolecules by the PC. The reported study was supported by grant № МК-2761.2019.2.