A novel electrochemical sensor modified by aspartic acid polymer and carbonized-ZIF-67 was prepared for arbutin detection. ZIF-67 was synthesized and carbonized, and then used as the substrate supporting of electrochemical sensor. Carbonized-ZIF-67 had a large specific surface and good electrical conductivity, which provided large electroactive area and promoted the electron transfer at the sensing interface. Aspartic acid polymer was prepared by cyclic voltammetry. Aspartic acid polymer could effectively absorb arbutin, resulting in the preconcentration of arbutin on sensor surface. Benefiting from the synergistic effect between carbonized-ZIF-67 and aspartic acid polymer, the prepared electrochemical sensor exhibited sensitive electrochemical response for arbutin. Under the optimum conditions, the electrochemical sensor achieved a wide linear range in the range from 5 to 110 μmol/L and a low detection limit of 0.41 μmol/L for arbutin. In practical application, the electrochemical sensor was employed to detect arbutin in green tea and whitening cream samples, exhibiting satisfactory recovery rates. With the outstanding features of easy operation, rapid response and high sensitivity, the prepared electrochemical sensor provided a convenient and effective tool for arbutin detection.
The coexistence of dopamine (DA) and acetaminophen (AC) in living organisms leading to an unexpected mutual interference in electrochemical detection techniques demands a simultaneous, selective as well as simple and cost-effective approach for DA and AC. Herein, a novel nanocomposite was fabricated by integrating carbonized ZIF-67 (C-ZIF-67) with carbon black Super P (SP) and introduced onto a glassy carbon electrode (GCE) to form a highly sensitive electrochemical sensor (C-ZIF-67/SP/GCE) for the simultaneous determination of DA and AC. The well-prepared nanomaterial presents a polyhedral morphology interlaced on a reticulated chain. C-ZIF-67/SP/GCE shows excellent electrocatalytic activity towards the redox reactions of DA and AC in a dynamic linear range up to 100 μM, which could be attributed to the synergistic effect of the large specific surface area of C-ZIF67 and the excellent conductivity of SP. The limits of detection (LODs, S/N = 3) of 0.58 μM and 0.27 μM were obtained for DA and AC, respectively. Moreover, the developed sensor exhibited good reproducibility and long-term stability. The C-ZIF-67/SP/GCE was employed to analyze DA and AC biomedical samples and satisfactory recoveries were achieved. This approach provides a simple, easy and sensitive method to detect DA and AC simultaneously and selectively.
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-ZIF 67 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 ZIF 67 , increasing the conductivity via carbonization of ZIF 67 , and multiplying the number of probe molecules via an enzyme catalyzed reaction . Experimental parameters, including the volume of C-ZIF 67 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.
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