A high sensitive impedimetric salbutamol immunosensor based on the gold nanostructure-deposited screen-printed carbon electrode

• A sea urchin-like AuNS was electrodeposited on SPCEs using templateless method.
• AuNS/SPCEs were constructed as disposable and label-free impedimetric immunosensors
• Detection limit of the immunosensors for salbutamol was as low as 4 fg/mL.

Salbutamol (SAL) is a β2-agonist which is illegally used as a growth-promoting agent in livestock, which can result in health risks to consumers. Highly sensitive label-free impedimetric immunosensors based on gold nanostructure (AuNS)-deposited screen-printed carbon electrodes (SPCEs) are used to detect SAL. Two-step templateless electrodeposition creates the AuNS in a sea urchin shape with submicrometer-scaled pyramidal structures on micrometer-scaled particles, and the roughness of the resulting AuNS/SPCEs is 4.9 times greater than that of polished gold disk electrodes (AuDE). Anti-SAL monoclonal antibody was immobilized on the 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide hydrochloride/N-hydroxysuccinimide-activated 3-mercaptoproponic acid-modified AuNS/SPCEs. Electron transfer resistance was measured using electrochemical impedance spectroscopy (EIS) to quantify the SAL concentration. Label-free AuNS/SPCE-based immunosensors presented a wide linear range from 0.1 pg/mL to 1 μg/mL and the limit of detection was as low as 4 fg/mL, which is much lower than that (3 pg/mL) obtained using the AuDE-based immunosensors. Moreover, the AuNS/SPCE-based immunosensors could practically quantify the concentration of SAL in 1000 time-diluted serum samples with a good recovery and are sufficiently sensitive to meet EU minimum required performance limit (< 3 ng/mL). The AuNS/SPCEs have promise for the development of disposable and label-free EIS-based immunosensors for the detection of small molecule chemicals, such as SAL.

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