Fig. 1 |. Synthesis of pH-responsive OCC-DNA complexes.

a, Schematic of the synthesis of OCC-DNA complexes. b, Schematic of the molecular mechanism of response that involves mechanism - protonation and deprotonation of the N,N-diethylamino moieties group on the aryl OCC. c, AFM image of OCC-DNA complex. Scale bar = 100 nm. Color map denotes height. d, Representative near-infrared fluorescence spectra of OCC-DNA complexes in PBS at pH 3.14 (red) and pH 7.02 (gray) at 575 nm excitation. The arrow indicates the redshift of ${\text{E}}_{{\text{11}}^{-}}$ centre wavelength in acidic buffer solution. e, Dynamics of OCC-DNA response and reversal in buffer at pH = 7.09 (gray arrows) and 3.32 (red arrows) at 575 nm excitation. The spectral shift $\mathrm{\Delta }{\text{E}=\text{E}}_{{\text{11}}^{-}}-{\text{E}}_{11}$ is as measured from the emission peak centre wavelengths.