Dual-mode electrochemiluminescence and fluorescence aptasensing platform based on resonance energy transfer for sensitive detection of estradiol

Herein, an electrochemiluminescence (ECL)-fluorescence (FL) dual-mode aptasensing system was proposed for estradiol detection. Firstly, ruthenium-based metal–organic framework nanosheets (RuMOFNSs) were synthesized by a simple one - pot method. RuMOFNSs exhibited both fluorescence (FL) and electrochemiluminescence (ECL) characteristics. After RuMOFNSs were immobilized on the electrode, complementary target DNA (cDNA), gold nanoclusters labeled aptamer (AuNCs-Apt) were successively assembled on the electrode to fabricate the aptasensor. The absorption spectrum of RuMOFNSs could be well overlapped with the fluorescence emission spectrum (or ECL spectrum) of AuNCs. When estradiol was absent, AuNCs-Apt could hybridize with cDNA to form double-stranded DNA, the close proximity between AuNCs and RuMOFNSs led to the efficient resonance energy transfer (RET) from AuNCs (donor) to RuMOFNSs (acceptor), thus the enhanced ECL (or FL) signals was achieved. In the presence of estradiol, the high affinity between Apt and estradiol led to the dissociation of double-stranded DNA, and the increased distance between AuNCs and RuMOFNSs hindered the RET, and the decreased ECL (or FL) signals were obtained. The aptasensor demonstrates exceptional sensitivity for detecting estradiol, with FL and ECL detection limits of 97 pM and 20 fM, respectively. This innovative approach offers significant potential for endocrine-disrupting chemical analysis.