(???????)Aggregation-induced emission-active fluorescent polymer sensors for the detection of water in organic solvents, Cu2+ and hemolysis

The hydrophobic polymer HDDA-EDT-SADA with aggregation-induced emission (AIE) property was synthesized via the thiol-ene click copolymerization of salicylaldehyde azine (SA) derivative diacrylate monomer SADA and commercially available 1,2-ethanedithiol (EDT) and 1,6-hexanediol diacrylate (HDDA). HDDA-EDT-SADA was found to display unexpected intense fluorescence in acetone and DMSO compared to that in other good solvents, which dramatically decreased by adding small amount of water. We demonstrate that HDDA-EDT-SADA can be used as a fluorescent sensor for water detection in acetone and DMSO. To improve the water solubility of the AIE-active polymer, SADA was copolymerized with dithiothreitol (DTT) and poly(ethylene glycol) diacrylate (PEGDA) to give an amphiphilic AIE polymer PEGDA-DTT-SADA. Similar fluorescence phenomenon was also found in DMF, suggesting that PEGDA-DTT-SADA could serve as an indicator for water detection in DMF. Thanks to the PEG segments and DTT units, the PEGDA-DTT-SADA was able to well-disperse in water via the formation of stable micelles. The PEGDA-DTT-SADA selectively complexed with Cu2+ and thus could be used as a fluorescent sensor for Cu2(+) detection in aqueous media. Moreover, the PEGDA-DTT-SADA could be utilized as a fluorescent sensor for hemolysis ratio detection of red blood cells (RBCs) due to the inner filter effect.