In situ synthesis of Au nanoparticles confined in 2D sheet-like metal organic frameworks to construct competitive PEC biosensor for sensitive analysis of autism spectrum disorder miRNA

Autism spectrum disorders (ASDs) have tremendous medical and social problems in the world, which have attracted accumulated attention on the related microRNAs (miRNAs) detection by photoelectrochemical (PEC) method. Herein, 1,2,4,5-benzenetetramine tetrahydrochloride (BTA) behaved as ideal ligand to chelate with chloroauric (AuCl4-) for forming two-dimensional (2D) sheet-like metal organic frameworks (MOFs) (termed AuCl4--MOFs), followed by in situ formation of gold nanoparticles (Au NPs) embedded in metal organic frameworks (defined as MOFs@Au NPs). The resulted MOFs@Au NPs showed 5.3-time increase in the anode photocurrent over Au NPs alone by using ascorbic acid (AA) as electron donor. Then, the PEC mechanism was strictly studied by electron paramagnetic resonance (EPR) and electrochemistry. Next, a label-free “signal on” model PEC biosensor was constructed based on MOFs@Au NPs as photosensitizer to detect miRNA-23a-3p (related with ASDs), integrated by a competitive reaction associated with magnetic bead (MB) linked double-stranded DNA (dsDNA). The sensor showed a wider linear range of 200 fM ∼ 2.00 nM (R2 = 0.99) and a limit of detection (LOD) down to 78.9 fM. This analytical strategy holds huge potential for blood-based RNA detection in biomedical field.