Triple signal-enhancing electrochemical aptasensor based on rhomboid dodecahedra carbonized-ZIF₆₇ for ultrasensitive...

C-reactive protein (CRP) is one of the most sensitive acute-phase reactants, which is an early stage indicator of cardiovascular disease and infectious inflammation in clinic. However, it is still challenging to accurately quantification the trace content of CRP molecules in plasma samples. In this work, we propose an ultrasensitive electrochemical CRP aptasensor based on rhomboid dodecahedra carbonized-ZIF₆₇ loaded with gold nanoparticle modified by aptamer. Aptamer biomolecules are binded to AuNPs via Au-thiol bonds for selectively capturing CRPs. The ultrasensitivity is achieved based on triple signal enhancing strategy: enhancing the specific surface area via the rhomboid dodecahedra structure of ZIF₆₇, increasing the conductivity via carbonization of ZIF₆₇, and multiplying the number of probe molecules via an enzyme catalyzed reaction. Experimental parameters, including the volume of C-ZIF₆₇ dispersion, electrodeposition time of AuNPs, incubation time of aptamer-CRP and aptamer-CRP concentration, are systemically investigated and optimized. Under optimal conditions, the proposed biosensor shows excellent sensing performance with the limit of detection (LOD) of 0.44 pg mL^-1 (S/N = 3), and a broad linear dynamic range of 10 pg mL^-1 ‒ 10 μg mL^-1 within the total readout time of 5 min. This work provides an effective electrochemical biosensor for CRP assay in plasma, being highly potential for applications in bioanalysis and point-of-care (POC) clinical diagnosis.