LAUSR

Cost-effective gas-phase synthesized single walled carbon nanotubes (SWCNTs) were first employed for the surface modification of indium tin oxides (ITO) via electrostatic coating of poly-l-lysine (PLL). Compared with control substrates of bare ITO and SWCNT-PLL-slide glasses, SWCNT-PLL-ITO, with high catalytic properties associated with large surface areas, showed significant improvement of electro catalytic activity toward the oxidation of dopamine (DA) and uric acid (UA). The cyclic voltammetric (CV) peak separation of oxidation for both DA and UA was estimated to be ∼ 0.13 V, which renders them capable of simultaneously detecting DA and UA in a mixed solution. The differential pulse voltammetry (DPV) technique was further performed to obtain a linear detection range of DA from 1.0 μM to 100 μM, and a detection limit of 1.0 μM was confirmed in the mixed solution. Furthermore, the practical analytical ability of the method was finally confirmed by selective detection of both DA and UA in human urine samples without any preliminary treatment, implying the feasibility of applying bio-sensors in a low-cost manner.