Application of Organic Nanoparticles as Fluorescence Probe in the Determination of Nucleic Acids

Abstract

Organic fluorescent nanoparticles (NPs) have been successfully synthesized by reprecipitation method under ultrasonic irradiation. In comparison with single organic fluorophores, these NPs are brighter, photo‐chemically stable, and water‐soluble. At acidic medium, the fluorescence of NPs is 60 times strong as that of 1‐pyrenemethylamine. They also have high room temperature fluorescence quantum yields (∼20%) and twice long fluorescence lifetime (∼0.2 µsec) as that of single organic fluorophores. A fluorescence method has been developed for rapid determination of DNA with these organic NPs as a fluorescence probe, based on the fluorescence quenching of NPs in the presence of DNA. Maximum fluorescence quenching is produced at pH 2.0 with maximum excitation and emission wavelengths of 238 and 400 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4–10.5 µg mL⁻¹ for calf thymus DNA (ct‐DNA) and 0.8–20.0 µg mL⁻¹ for fish sperm DNA (fs‐DNA). The corresponding detection limit is 0.019 µg mL⁻¹ for ct‐DNA and 0.022 µg mL⁻¹ for fs‐DNA. The relative standard deviation of six replicate measurements is 1.3–2.2%. The method is simple, rapid, and sensitive. The recovery and relative standard deviation are very satisfactory.

Keywords:

• Fluorescence probe
• Nucleic acids
• Organic nanoparticles
• 1‐Pyrenemethylamine
• ct‐DNA and fs‐DNA

Acknowledgments

This work was supported by the Natural Science Foundation for Young Teacher of Anhui Province Education Commission (2004jq121), the National Natural Science Foundation of China (20375001) and the Natural Science Foundation of Anhui Province (03044904).