Sulfo cy5

Lanthanide luminescence in homogeneous solutions was measured with a Tecan Infinite M1000 Pro microtiter plate reader, using the instrument configurations described in Supplementary Table 3. Sulfo-Cy3 and Sulfo-Cy5 reagents were purchased from Lumiprobe; Atto 610 and sodium ascorbate from Sigma-Aldrich; and dNTPs from Life Technologies. To determine the lifetimes of LRET-mediated lanthanide luminescence, signal intensities were measured for a series of ‘time slices.’ Collection times were fixed at 100 µs, and the temporal delay was varied from 0 to 400 µs. The integrated signal intensities of these time slices were fitted to the equation below using MATLAB software (version R2015b).
$$y(t)=c\times {\int }_{\mathit{\text{delay}}}^{\mathit{\text{delay}}+100}{e}^{-t/\tau }\mathit{\text{dt}}$$ To compare the integrated signal intensities of Eu³⁺/ATBTA complexes in the absence and presence of 10 µM Atto 610 (i.e., integrated emission spectra from 0 µs after excitation to infinity), emission photons were collected for 2 ms (maximum collection time permitted by the instrument) after a delay of 30 µs. The measured signal intensities for this pulse cycle and average luminescence lifetimes (1020 and 17 µs in the absence and presence of Atto 610, respectively) were then used to calculate total photon emissions for each experimental condition.