HP-cyclodextrin modified sulphur quantum dots for the fluorescent cage sensing of p-NP by structural matching and PET: a new sensing approach

Abstract

Nitrophenols are manufactured chemicals used in making industrial products and released from auto exhaust. Once nitrophenols enter the soil, the phytotoxicity causes forest decline. Exposure to nitrophenols will result in adverse health effects, such as cataracts, cyanosis and potential carcinogenicity. Based on structural matching, this study describes a sensing system of 2-hydroxylpropyl-β-cyclodextrin (HP-β-CD) modified sulphur quantum dots (HP-SQDs) for the selective detection of para-nitrophenol (p-NP). HP-SQDs are synthesized by the assembly fission method. The cyclodextrin-based molecular cages detected p-NP selectively by fluorescence quenching, which resulted from the structural matching and photoinduced electron transfer (PET) between p-NP and HP-β-CD. The inclusion of nitrophenols in cyclodextrin cages causes the decreased fluorescence intensity of HP-SQDs, with the detection limit of 0.25 μmol L⁻¹ for p-NP. The theoretical calculation of the binding energy and inclusion constant between HP-β-CD and nitrophenols reveals the high selectivity of p-NP over other isomers by HP-SQDs. This fluorescent cage sensing approach provides a new idea for the identification of isomers.