The detailed method of the synthesis of small organic molecule POZ-M NPs and their characterization can be found in the ESI. Fig. depicts the chemical structures of POZ -M, and amphiphilic polymer surfactants (PEG-PS-COOH and ABA) used in the preparation of negatively charged POZ-M(-) NPs and positively charged POZ-M(+) NPs respectively. In the POZ-M molecule two thiophene π units are covalently linked to the phenoxazine core and two aldehyde units act as electron-withdrawing units to increase intramolecular charge separation. Both POZ-M(-) and POZ-M(+) NPs as prepared formed stable dispersion with the average particle size of 38 and 43 nm respectively, as determined by dynamic light scattering (DLS, Fig. ). Negative surface charge of POZ-M(-) NPs (ξ = -24 mV) arose from the carboxyl groups of the PEG-PS-COOH surfactant (Fig. ), while tertiary amine groups of the ABA surfactant susceptible to interaction with CO2 were responsible for the positive surface charge of POZ-M(+) NPs (ξ = +26 mV).