By preparing gold nanoparticles-graphdiyne (Au-GDY) as sensing substrate and [Ru(NH 3 ) 6 ] 3+ -UiO-66-NH 2 MOFs (Ru-UiO-66) as signaling probe as well as linking the as-prepared Au-GDY and Ru-UiO-66 with the specific peptide (PT) of MMP-7 to form Ru-UiO-66/PT/Au-GDY, a cost-effective and sensitive electrochemical sensor was designed for the detection of matrix metalloproteinase-7 (MMP-7) which is an important biomarker for tumor and biliary atresia. The superior electrical properties, easy preparation, large surface area, and high stability of Au-GDY make it be a desirable substrate to immobilize PT. The unique structure of UiO-66-NH 2 is beneficial to assemble [Ru(NH 3 ) 6 ] 3+ probe and link PT. In the absence of MMP-7, the Ru-UiO-66/PT/Au-GDY modified electrode exhibited a prominent peak current of [Ru(NH 3 ) 6 ] 3+ , which is decreased after the addition of target MMP-7 since it can specifically recognize and cleave PT to induce the Ru-UiO-66 leave the electrode. The experimental results showed that the decrease of the [Ru(NH 3 ) 6 ] 3+ signal has a linear relation with the concentrations of MMP-7 in the range 0.01 pg mL −1 –10.0 ng mL −1 . By optimizing experimental conditions, the achieved detection limit (LOD) for MMP-7 is 5.0 fg mL −1 . The analysis of real serum samples has excellent accuracy. The simplicity of preparation and sensitivity make the Ru-UiO-66/PT/Au-GDY sensor a considerable promising analysis tool for MMP-7 detection. Graphical abstract
Energy levels in organisms are closely linked to metabolic diseases, with ATP—the universal energy currency—playing a central role in this relationship. This paper presents a novel electrochemical biosensor for ATP, integrating homogeneous bio-recognition reactions with terminal deoxynucleotidyl transferase (TdT)-mediated polymerization to enable precise ATP detection in metabolic research. Initially, a DNA oligonucleotide composed of a camouflaged aptamer and exposed hairpin DNA was designed to react homogeneously with ATP in the presence of exonuclease I (Exo I). This reaction generates blunt-ended hairpin DNA, which can activate the assembly of an ordered DNA-rich nanostructure layer on the gold electrode. Subsequently, the DNA strand is elongated through TdT-induced polymerization in the presence of deoxynucleotide triphosphates (dNTPs). A significant amount of Ru(NH 3 ) 6 3+ can be adsorbed onto the negatively charged DNA phosphate backbone via strong electrostatic interactions, effectively amplifying the detection signal and enhancing the sensor's performance. Under optimal conditions, the system exhibits excellent linearity over the target concentration range of 10 −2 to 10 3 nM, with a detection limit as low as 8.37 pM, enabling the detection of trace amounts of ATP. The biosensor demonstrates high stability and reliability, with recovery rates ranging from 97.8 % to 110 %. This method serves as a diagnostic tool to assess organismal metabolic status by monitoring ATP levels, enabling the tracking of metabolic disease progression. By integrating molecular monitoring with clinical diagnosis, it offers a potential approach for the preventing and intervention of metabolic diseases.
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