Signal-on electrochemiluminescence biosensor for hepatitis B virus DNA based on energy transfer between gold nanoclusters and magnetically Fe3O4@Ru@SiO2 probe.

Based on the well matching between the emission of gold nanoclusters (AuNCs) and the absorption of ruthenium complex-doped magnetic silica nanoparticles (Fe3O4@Ru(bpy)32+@SiO2, simply as Fe3O4@Ru@SiO2), these two nanoparticles were employed as the energy donor and acceptor, respectively, to develop a signal-on electrochemiluminescence resonance energy transfer (ECL-RET) biosensor for the sensitive and selective detection of hepatitis B virus (HBV) DNA (chosen as a model target). Two DNAs (H1 and H2) capable of hybridizing with the target DNA were designed and modified on the nanoparticles to form Fe3O4@Ru@SiO2-H1 and AuNCs-H2. In the presence of target DNA, a hybridization cascade brought AuNCs into close proximity with Fe3O4@Ru@SiO2, the non-radiative energy transfer process allows the energy of AuNCs to be transferred to Fe3O4@Ru@SiO2, resulting in enhanced ECL from Fe3O4@Ru@SiO2. Magnetic separation technology was integrated to effectively remove interfering substances from complex matrices, further improving detection specificity. Under optimized conditions, the enhanced ECL intensity (ΔI) showed a good linear correlation with the logarithmic concentration of HBV DNA from 1.0 fM to 1.0 nM, with a detection limit of 0.33 fM. The proposed biosensor has been successfully applied for the detection of HBV DNA in clinical serum samples with satisfactory results. This study provides a promising strategy for nucleic acid analysis and demonstrates the great potential of the ECL-RET platform in clinical diagnostics and highly sensitive biomarker detection.