An amphiphilic ratiometric fluorescent probe with aggregation-induced emission feature for specific detection of hypochlorite in aqueous solution and living cells

Hypochlorite (ClO-) as one of reactive oxygen species (ROS), that has been widely used in our daily life and played a crucial role in immune function systems of living organisms. However, due to the hydrophobic nature of most fluorescent probes, direct utilization of these probes for detection of ClO- in biological systems has demonstrated to be problem. In this work, hydrophilic amino-terminated polyethylene glycol (PEG-NH2) and the organic dye (named as TPAMA) with aggregation-induced emission (AIE) feature were conjugated together using hexachlorocyclotriphosphazene (HCCP) as linking agent. The resultant probe (named as TPAMA-HCCP-PEG) was examined as ratiometric fluorescent probe for detection of ClO- in pure aqueous solution by taking advantage of its amphiphilic property. After adding ClO-, the fluorescence of TPAMA was quickly quenched, therefore it can be used for sensing ClO- with high sensitivity and selectivity. The mechanism was attributed to the reaction of TPAMA with ClO-, resulting in a blue-shift in absorbance and fluorescence emission. The potential of TPAMA-HCCP-PEG for sensing ClO- in biological systems was also evaluated further. Results showed that TPAMA-HCCP-PEG could form highly dispersible nanoparticles in aqueous solution and displayed low cytotoxicity towards model cancer cell lines, making it promising for monitoring ClO- in living systems. We believe this work will provide a general tool for fabrication of fluorescent probes suitable for visual detection various molecules with important biological roles.