NaEuF 4 /Au@Ag 2 S 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 NaEuF4 nanoparticles (NPs) and Au@Ag2 S NPs as the energy donor-acceptor pair for the first time. The NaEuF4 /Au@Ag2 S NPs-based FRET DNA sensor was constructed with NaEuF4 NPs as the fluorescence (FL) donor and Au@Ag2 S core-shell NPs as FL acceptor. In order to find the matching energy acceptor, the amount of AgNO3 and Na2 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 Eu3+ 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/F0 , ΔFL=F-F0 ) of FL was logarithmically related to the concentration of the target DNA, ranging from 100aM to 100pM. 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.