Construction of a novel semiconducting polymer dots-based ratiometric fluorescence nanoprobe for DNA detection

A ratiometric fluorescent deoxyribonucleic acid (DNA) probe was synthesized using the photoinduced electron transfer (PET) mechanism, involving the interactions between different fluorescent components and electron acceptors. Double-emission carboxyl-functionalized semiconducting polymer dots with an average diameter of 26.7 nm were synthesized using the nanoprecipitation method and applied as a fluorophore, and methylene blue (MB) was used as the electron acceptor. PET between different polymer dots components and MB can achieve ratiometric modulation of the overall fluorescence in the system. The addition of DNA restores the fluorescence intensity, because the strong interactions between DNA and MB result in MB being separated from the polymer dots. Under optimized experimental conditions, system fluorescence was restored to its maximum when the concentration of DNA reached 200 nM; the linear range was 0.006–200 nM ( R 2  = 0.995). This probe was reasonably free from interference, showing a good response to DNA, with strong application data from actual samples.