We report for the first time the non-covalent functionalization of multiwall carbon nanotubes (MWCNTs) with polyarginine (Polyarg), the modification of glassy carbon electrodes (GCE) with the resulting Polyarg-MWCNTs dispersion and the analytical application of Polyarg-MWCNTs-modified GCE for the quantification of uric acid. The optimum MWCNT-Polyarg dispersion was obtained by sonicating for 5.0 min the mixture of 0.75 mg mL−1 MWCNTs and 0.50 mg mL−1 Polyarg. The dispersion was characterized by scanning electron microscopy, electrophoretic mobility, electrochemical impedance spectroscopy, cyclic voltammetry and amperometry. The presence of MWCNT-Polyarg at GCE surface produced a drastic decrease in the overvoltages for the oxidation of hydrogen peroxide (300 mV) ascorbic acid (281 mV) and uric acid (70 mV) and for the reduction of hydrogen peroxide (200 mV), as well as an important decrease in the charge transfer resistances for hydrogen peroxide, hydroquinone/quinone and ferricyanide/ferrocyanide markers. The strong adsorption of uric acid at GCE/MWCNT-Polyarg made possible the highly sensitive detection of this biomarker at nanomolar levels even in the presence of 1.0×10−4 M ascorbic acid by Adsorptive Stripping with medium exchange and linear scan voltammetry transduction. The quantification of uric acid in untreated human urine was very successful, demonstrating an excellent correlation (98 %) with the reference method used in clinical laboratories (Uricostat, Wiener Lab).

中文翻译：

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多壁碳纳米管与聚精氨酸的非共价功能化：尿酸定量的表征和分析应用

我们首次报告了多壁碳纳米管 (MWCNTs) 与聚精氨酸 (Polyarg) 的非共价功能化、玻璃碳电极 (GCE) 的改性以及由此产生的 Polyarg-MWCNTs 分散体以及 Polyarg-MWCNTs 改性的分析应用用于定量尿酸的 GCE。通过对 0.75 mg mL-1 MWCNTs 和 0.50 mg mL-1 Polyarg 的混合物进行超声处理 5.0 分钟，获得最佳 MWCNT-Polyarg 分散体。通过扫描电子显微镜、电泳迁移率、电化学阻抗谱、循环伏安法和电流分析法表征分散体。GCE 表面 MWCNT-Polyarg 的存在使过氧化氢 (300 mV)、抗坏血酸 (281 mV) 和尿酸 (70 mV) 的氧化以及过氧化氢 (200 mV) 的还原过电压急剧下降，以及过氧化氢、氢醌/醌和铁氰化物/亚铁氰化物标记物的电荷转移电阻的显着降低。GCE/MWCNT-Polyarg 对尿酸的强吸附使得即使在存在 1.0×10-4 M 抗坏血酸的情况下，通过介质交换和线性扫描伏安法转导的吸附剥离也能以纳摩尔水平高度灵敏地检测该生物标志物。未经处理的人尿中尿酸的定量非常成功，证明与临床实验室使用的参考方法（Uricostat，