Nonenzymatic amperometric sensor for ascorbic acid based on hollow gold/ruthenium nanoshells

• We synthesized hollow gold/ruthenium (hAu–Ru) nanoshells for ascorbic acid sensing.
• The hAu–Ru nanoshells showed sensitivity of 426 μA mM−1 cm−2 for ascorbic acid.
• Good selectivity against glucose, uric acid, dopamine, 4-acetamidophenol, and NADH.
• The linear dynamic range appeared from zero to 2.0 mM (R = 0.9995).
• Response time (1.6 s) and low detection limit (2.2 μM) were obtained at pH 7.40.

We report a new nonenzymatic amperometric detection of ascorbic acid (AA) using a glassy carbon (GC) disk electrode modified with hollow gold/ruthenium (hAu–Ru) nanoshells, which exhibited decent sensing characteristics. The hAu–Ru nanoshells were prepared by the incorporation of Ru on hollow gold (hAu) nanoshells from Co nanoparticle templates, which enabled AA selectivity against glucose without aid of enzyme or membrane. The structure and electrocatalytic activities of the hAu–Ru catalysts were characterized by spectroscopic and electrochemical techniques. The hAu–Ru loaded on GC electrode (hAu–Ru/GC) showed sensitivity of 426 μA mM−1 cm−2 (normalized to the GC disk area) for the linear dynamic range of <5 μM to 2 mM AA at physiological pH. The response time and detection limit were 1.6 s and 2.2 μM, respectively. Furthermore, the hAu–Ru/GC electrode displayed remarkable selectivity for ascorbic acid over all potential biological interferents, including glucose, uric acid (UA), dopamine (DA), 4-acetamidophenol (AP), and nicotinamide adenine dinucleotide (NADH), which could be especially good for biological sensing.

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