The fluorescent dye ATTO-425 from ATTO-TEC (Germany), N-acetyl tryptophan amide (NATA) from Sigma (USA) and PBS buffer from Sigma (USA) were used without further purification. ATTO-425 was dissolved in PBS buffer (pH 7.4), and NATA was dissolved in distilled water.
Fluorescence measurements were performed in a homemade spectrofluorimeter [20] (link) and Fluorolog-3 (Horiba, Japan), which have vertical slits and a Cary Eclipse spectrofluorimeter (Agilent Technologies, Australia), which has horizontal slits. Fluorescence measurements in the Fluorolog-3 (Horiba, Japan) were performed in the Resource Center for Optical and Laser Materials Research of St. Petersburg State University, Russia. The fluorescence emission and excitation spectra of NATA were recorded at λex = 280 nm and λem = 350 nm, respectively. The fluorescence excitation spectra of ATTO-425 were recorded at different wavelengths of emission in the range from 470 nm to 550 nm with a step of 10 nm. The fluorescence spectra of ATTO-425 were recorded with λex = 436 nm, corresponding to the maximum of the long-wavelength band of the dye.
All the concentrational dependences for NATA and ATTO-425 were measured at constant experimental conditions (the excitation slit and emission slit values, the scan speed and the setting of PMT Detector Voltage). In particular for Cary Eclipse spectrofluorimeter excitation and emission slits were 5 nm, the scan speed was 600 nm/min, PMT Detector Voltage was in the range 410–530 V. Once chosen it was unchanged for measurement all spectra for plotting the dependence of F(λex) on AFL. All experiments were performed in a cell of dimensions 10×10×4 mm Starna Cells, Inc (USA).
The fluorescence quantum yield of ATTO-425 was taken as 0.9 (Product cataloque 2013/2015, ATTO-TEC GmbH, Germany), and the fluorescence quantum yield of NATA was taken as 0.14 [21] . The absorption spectra were recorded using a U-3900H spectrophotometer (Hitachi, Japan) in cells from Hellma GMBH & Co. (Germany) with different optical path lengths: 10, 1, 0.1 and 0.01 mm (100-QS 10, 100-QS 1, 106-QS 0.1 and 106-QS 0.01 with cell holder 013.000).
Fluorescence measurements were performed in a homemade spectrofluorimeter [20] (link) and Fluorolog-3 (Horiba, Japan), which have vertical slits and a Cary Eclipse spectrofluorimeter (Agilent Technologies, Australia), which has horizontal slits. Fluorescence measurements in the Fluorolog-3 (Horiba, Japan) were performed in the Resource Center for Optical and Laser Materials Research of St. Petersburg State University, Russia. The fluorescence emission and excitation spectra of NATA were recorded at λex = 280 nm and λem = 350 nm, respectively. The fluorescence excitation spectra of ATTO-425 were recorded at different wavelengths of emission in the range from 470 nm to 550 nm with a step of 10 nm. The fluorescence spectra of ATTO-425 were recorded with λex = 436 nm, corresponding to the maximum of the long-wavelength band of the dye.
All the concentrational dependences for NATA and ATTO-425 were measured at constant experimental conditions (the excitation slit and emission slit values, the scan speed and the setting of PMT Detector Voltage). In particular for Cary Eclipse spectrofluorimeter excitation and emission slits were 5 nm, the scan speed was 600 nm/min, PMT Detector Voltage was in the range 410–530 V. Once chosen it was unchanged for measurement all spectra for plotting the dependence of F(λex) on AFL. All experiments were performed in a cell of dimensions 10×10×4 mm Starna Cells, Inc (USA).
The fluorescence quantum yield of ATTO-425 was taken as 0.9 (Product cataloque 2013/2015, ATTO-TEC GmbH, Germany), and the fluorescence quantum yield of NATA was taken as 0.14 [21] . The absorption spectra were recorded using a U-3900H spectrophotometer (Hitachi, Japan) in cells from Hellma GMBH & Co. (Germany) with different optical path lengths: 10, 1, 0.1 and 0.01 mm (100-QS 10, 100-QS 1, 106-QS 0.1 and 106-QS 0.01 with cell holder 013.000).
Free full text: Click here
