Highly selective and sensitive biological probe for cysteine detection based on fluorescence resonance energy transfer between lanthanide oxysulfide nanoparticles and Au nanoparticles

Biothiols are biologically important targets because their transport and metabolism are closely related to the activities of many proteins and biological enzymes. In this paper, a kind of biological probe based on the fluorescence resonance energy transfer between lanthanide oxysulfide and gold nanoparticles was developed for the detection of cysteine. Ln 2 O 2 S:Tb 3+ and Ln 2 O 2 S:Eu 3+ nanoparticles were prepared by a thermolysis method. The as-prepared fluorescent nanoparticles were modified by polyethylenimine ligand exchange to increase their hydrophilicity. Then, Au nanoparticles were added to form fluorescence resonance energy transfer systems in which Au NPs and La 2 O 2 S:Ln 3+ act as the acceptor and donor, respectively. Among the Ln 2 O 2 S:Tb 3+ and Ln 2 O 2 S:Eu 3+ systems, the cysteine content and fluorescence intensity showed good proportional proportionality, with detection limits of 6.75 nM and 14.09 nM in the range of 50∼1500 nM, respectively. The results of anti-interference experiments showed that this biological probe is highly selective for cysteine detection.