NaEuF4/Au@Ag2S nanoparticles-based fluorescence resonant transfer DNA sensor for ultrasensitive detection of DNA energy

The work investigates a new fluorescence resonance energy transfer (FRET) system using NaEuF 4 nanoparticles (NPs) and [email protected] 2 S NPs as the energy donor–acceptor pair for the first time. The NaEuF 4 / [email protected] 2 S NPs-based FRET DNA sensor was constructed with NaEuF 4 NPs as the fluorescence (FL) donor and [email protected] 2 S core−shell NPs as FL acceptor. In order to find the matching energy acceptor, the amount of AgNO 3 and Na 2 S were controlled in the synthesis process to overlap the absorption spectrum of energy acceptor with the emission spectrum of energy donors. The sensitivity of FRET-based DNA sensor can be enhanced and the self-absorption of ligand as well as the background of signals can be decreased because of Eu 3+ which owns large Stokes shifts and narrow emission bands due to f–f electronic transitions of 4f shell. We obtained the efficient FRET system by studying suitable distance between the donor and acceptor. Then the FRET-based DNA sensor was used for the design of specific and sensitive detection of target DNA and the quenching efficiency (ΔFL/F 0 , ΔFL=F−F 0 ) of FL was logarithmically related to the concentration of the target DNA, ranging from 100   aM to 100   pM. We can realize an ultrasensitive detection of target DNA with a detection limit of 32 aM. This proposed method was feasible to analyse target DNA in real samples with satisfactory results.