Nanolog 3 spectrofluorometer

Photoluminescence excitation (PLE) measurements, performed on a Jobin-Yvon Nanolog-3 spectrofluorometer coupled with an InGaAs detector, were used for in vitro screening of polymer-wrapped SWNTs against the plant hormone analyte library. 2 mg/L stock suspensions of polymer-wrapped SWNTs were prepared in MES buffer (10 mM MES, 10 mM MgCl₂, pH 5.5) and added to a four-sided quartz cuvette. All analytes except H₂O₂ were dissolved in DMSO at 50 mM while 3% hydrogen peroxide was diluted to 50 mM in deionized water. 2 μL of each analyte was added to 998 μL of SWNT suspension, to obtain final analyte concentration of 100 μM. Samples were excited at wavelength 785-nm, with band-width of ±25 nm while nIR emission was collected in the wavelength range of 900-1600 nm. Integration time of each emission scan was 30 s. The total SWNT fluorescence counts obtained from the spectra were integrated across 900-1400 nm to account for all major SWNT chiralities. Total SWNT fluorescence was measured before and after addition of plant hormone analytes and fluorescence intensity change is calculated by taking a ratio of the two. For 2D excitation-emission map, the excitation wavelength is tuned at 5 nm steps from 500 to 800 nm, while SWNT fluorescence is generated across 900-1300 nm at each step. Integration time of each scan was 30 s, and an entire map was generated within 30 min.