Catalytically synthesized Prussian Blue nanozymes as labels for electrochemical DNA/RNA sensors.

We propose catalytically synthesized nanozymes based on Prussian Blue (PB) and azidomethyl-substituted poly (3,4-ethylenedioxythiophene) (azidomethyl-PEDOT) as novel electrocatalytic labels for DNA/RNA sensors. Catalytic approach allowed to synthesize highly redox and electrocatalytically active Prussian Blue nanoparticles functionalized with azide groups that enable 'click' conjugation with alkyne-modified oligonucleotides. Both competitive and sandwich-type schemes were realized. As the sensor response the direct (mediator-free) electrocatalytic current of H 2 O 2 reduction can be measured, which is proportional to the concentration of the hybridized labeled sequences. The current of H 2 O 2 electrocatalytic reduction is only 3–8 times increased in the presence of the freely diffusing mediator catechol, which indicates high efficiency of direct electrocatalysis with the elaborated labels. Electrocatalytic amplification of the signal allows robust detection of (63–70)-base target sequences with concentrations below 0.2 nM in blood serum within an hour. We believe, the use of advanced Prussian Blue based electrocatalytic labels sets new avenues for point-of-care DNA/RNA sensing. [Display omitted] • Catalytically synthesized functionalized nanozymes possess high catalytic activity. • Nanozyme functionalization with azide groups enables 'click' conjugation. • Efficient direct electrocatalysis with the labels provides mediator-free operation. • Electrocatalytic signal amplification allows detecting down to 0.01 nM of DNA. [ABSTRACT FROM AUTHOR]