Supercritical fluid-assisted fabrication of Cu OSAS-based electrochemical sensor for cysteine detection with enhanced sensitivity and reduced oxidation potential

Biosensing of Cysteine through the Induction of Oxygen Vacancies in a Cu/Zr Heterostructure Prepared by Supercritical Antisolvent Technique

“…Figures and S1 illustrate the process of pumping the mixed solution into the supercritical CO 2 to precipitate the precursor powder using a supercritical granulation instrument (Waters, S.N. 3937782, Massachusetts, USA) after setting the temperature, pressure, CO 2 flow rate, and solution injection rate. ,, Experimental conditions were optimized by comparing feeding ratio, pressure, solvent properties, and injection rate with the assistance of morphology and structural characterization techniques such as scanning electron microscopy to obtain the optimal grouping of morphology properties. Under the action of the cross-linking agent PVP, two metal salts are thoroughly combined in a high mass transfer environment of supercritical CO 2 , forming regular spherical structures through pressure relief precipitation.…”

“…Ultrapure water (18.2 MΩ·cm) was used for the preparation of all aqueous solutions. The Cu/Zr material (CZ SAS ) was synthesized following the procedures outlined in the relevant literatures. ,,− Cu­(NO 3 ) 2 ·3H 2 O, PVP-58k ( M w = 58000), phosphoric acid (AR), anhydrous potassium dihydrogen phosphate (KH 2 PO 4 (99.5%)), sodium dihydrogen phosphate (NaH 2 PO 4 (AR)), methanol (AR), ethanol (AR), and zirconium acetylacetonate (Zr­(acac) 4 (98%)) were purchased from Shanghai Macklin Biochemical Co., Ltd. Acetone (AR) was purchased from Sigma Ltd. (St. Louis, USA). High-purity CO 2 (99.9%) was obtained from Xiamen Rihong Air Products Co., Ltd. Cys (99%) was purchased from Aladdin Reagent Co., Ltd. (Shanghai).…”

“…The described reaction processes provide insight into the catalytic oxidation mechanism of Cys on copper oxide/zirconia composite materials. This mechanism is ascribed to the presence of oxygen vacancies on the oxide surface, which play a pivotal role in facilitating electron transfera crucial aspect of the catalytic process . While the proposed mechanism offers a plausible pathway for the catalytic oxidation, determining specific reaction pathways and rate constants necessitates comprehensive exploration through both experimental investigations and theoretical calculations.…”