Incorporating β-cyclodextrin with ZnO nanorods: a potentiometric strategy for selectivity and detection of dopamine

Hypha-templated synthesis of carbon/ZnO microfiber for dopamine sensing in pork

Carbon/ZnO coaxial microfibers were synthesized with the hypha of Penicillium expansum as low-cost and green template. The SEM images, XRD and Raman spectra were used to characterize the morphology and chemical components of the prepared microfibers. The formation of the coaxial structure could be attributed to the attachment of Zn²⁺ onto the hypha surface through coordination and electrostatic interactions. Sensing performance of the carbon/ZnO microfibers toward Dopamine (DA) were evaluated by dropping method. Results showed that the proposed sensor exhibited good selectivity, reproducibility, and stability with a detection limit of 0.106 μM. Two linear ranges were obtained from 0 to 50 and 50 to 300 μM. The practicality of the carbon/ZnO microfibers was supported by the successful detection of DA in pork with recovery ranging from 96.85% to 104.51%. Based on the excellent electrochemical performance and easy preparation, the proposed sensor provides a promising method for determination of DA.

Novel biosensing system for the simultaneous multiplex fluorescent determination of catecholamines and their metabolites in biological liquids

A novel original biosensing system for the simultaneous multiplex determination of general markers of catecholamine-producing diseases - catecholamines (dopamine, epinephrine, norepinephrine) and their metabolites (homovanillic and vanillylmandelic acids) in biological liquids without preliminary separation of analytes, in the absence of specific antibodies and receptors and with minimum pretreatment of a samples has been developed. This outstanding approach includes the unique combination of obtaining highly fluorescent derivatives of the analytes as a result of their interaction with two different amines ̶ benzylamine and 1,2-diphenylethylenediamine in the presence of peroxidase as a catalyst, with the application of first-order derivative fluorescence spectroscopy for the resolution of their spectra. Fluorescence is measured in 96-well microplates, which wells contain a bio-recognizing film consisted of horseradish peroxidase immobilized in the polymer chitosan. Spectra of the solutions are recorded in the range 400-500 nm (λ_ex ∼ 305-356 nm). The proposed procedures provide sensitive (in the range of 3-200 nM), selective, and reproducible (RSDs ≤ 1%, n = 6) multiplex determination of the catecholamines and their metabolites in biological liquids were successfully applied for the rapid simultaneous (20 samples per 15-30 min) screening of human urine and mice blood plasma. The validated results showed good linearity, precision, accuracy and selectivity of this method.