Assembly of layer-by-layer films of superoxide dismutase and gold nanorods:A third generation biosensor for superoxide anion

摘要

Based on the layer-by-layer self-assembly of positively charged cetyltrimethylammonium bromide (CTAB) wrapped gold na- norods (AuNRs) and negatively charged superoxide dismutase (SOD) from their aqueous solutions on cysteine modified gold electrode (Cys/Au), a third generation electrochemical biosensor ((SOD/AuNRs)2/Cys/Au) for superoxide anion (O2·-) was developed. The two layers assembly of SOD/AuNRs can significantly enhance the direct electron transfer between SOD and the electrode. The functional enzymatic activities of the SOD offer an electrochemical approach to the determination of O2·-. In the reductive regions, the proposed sensor exhibits excellent analytical performances, such as wide linear range (200 nM to 0.2 mM O2·-), low detection limit (100 nM O2·-), high sensitivity (22.11 nA cm-2 μM-1), short response time (less than 5 s), good stability and reproducibility, while no obvious interferences are caused by commonly met interfering species including hydrogen peroxide (H2O2), uric acid (UA) and ascorbic acid (AA).