Preparation of Carbon Quantum Dots for Fluorescence Detection of Environmental Pollutants

A kind of fluorescence sensing probe which used DNA aptamers as biorecognition elements and carbon quantum dots as signal amplification molecules was developed for the rapid detection of 3,3'4,4'-tetrabiphenyl (PCB77) with high selectivity. Carbon quantum dots were synthesized by hydrothermal synthesis method. Quantum dots and DNA were combined by the crosslinker. The crosslinking conditions such as pH, time, and temperature were also be explored. The sensing probe demonstrated two linear responses with PCB77 concentrations ranging from 1.0×10^-9 mol L^-1 to 1.0×10^-8 mol L^-1 and 1.0×10^-7 mol L^-1 to 3.0×10^-6 mol L^-1. The standard recovery rate was found to be 86.6% to 89.9% and the detection limit as 7.6×10^-10 mol L^-1. The sensing probe was also used to differentiate 3,3'4,4'-Tetrabiphenyl (PCB77) from other competing PCB congeners, including 3,3',4,4',5-pentachlorobenzene (PCB126), 4-chlorobiphenyl (PCB003) and 2,3-dichlorobiphenyl (PCB005), which showed that PCB77 could also be selectively detected when co-existing with other interference existed. Therefore, this fluorescence sensor can be a valuable tool for selective and rapid detection of PCB77 pollutant.