A dual-emission Förster resonance energy transfer nanoprobe for sensing/imaging pH changes in the biological environment.

A dual-emission nanoprobe that can sense changes in the environmental pH is designed based on the concept of pH-responsive Förster resonance energy transfer induced by the conformational transition of an associating polyelectrolyte, N-palmitoyl chitosan, bearing a donor (Cy3) or an acceptor (Cy5) moiety. We demonstrate that the developed pH-responsive nanoprobe can be used to ratiometrically image and thus discriminate the pH changes in the biological environment at different length scales.