Fig. 1. Fluorescent emission spectra of 5 μM probe N1 incubated with different concentrations of hERG transfected HEK293 membrane (0.8, 0.6, 0.4, 0.2, 0.1, and 0 mg mL^–1) for 20–30 min in the assay buffer (50 mM Tris-HCl, 1 mM MgCl₂, 10 mM KCl) at room temperature (λ_ex = 440 nm).