Water-dispersible hyperbranched conjugated polymer nanoparticles with sulfonate terminal groups for amplified fluorescence sensing of trace TNT in aqueous solution

Abstract

Conjugated polymers (CPs) have been recognized as promising fluorescent sensing materials for 2,4,6-trinitrotoluene (TNT) vapor. However, their applications for TNT detection in aqueous solution are restricted because of their low sensitivity (detection limits >90 nM). Here we report highly sensitive detection of TNT by water-dispersible hyperbranched conjugated polymer nanoparticles (HCPN-S) with hydrophobic CP cores and hydrophilic sulfonate terminal groups. Based on efficient TNT encapsulation by numerous hydrophobic cavities inside the hyperbranched CP core, HCPN-S exhibits a quenching constant of 1.21 × 10⁶ M⁻¹, two to three orders of magnitude higher than those of CP analogues, allowing amplified detection of TNT with a detection limit of 0.8 ppb (3.7 nM), which is the best result for CP-based fluorescent sensors for TNT detection in water reported so far. Furthermore, HCPN-S can selectively detect TNT even in the presence of 2,4,6-trinitrophenol and other nitro compounds.