Summary: | In this study, we fabricated platinum nanoparticles (PtNP)-decorated, porous reduced graphene oxide (rGO)–carbon nanotube (CNT) nanocomposites on a PtNP-deposited screen-printed carbon electrode (PtNP/rGO–CNT/PtNP/SPCE) for detection of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), which is released from prostate cancer cells LNCaP. The PtNP/rGO–CNT/PtNP/SPCE was fabricated by a simple electrochemical deposition and co-reduction method. In addition, the amperometric response of the PtNP/rGO–CNT/PtNP/SPCE electrode was evaluated through consecutive additions of H<sub>2</sub>O<sub>2</sub> at an applied potential of 0.2 V (vs. Ag pseudo-reference electrode). As a result, the prepared PtNP/rGO–CNT/PtNP/SPCE showed good electrocatalytic activity toward H<sub>2</sub>O<sub>2</sub> compared to bare SPCE, rGO–CNT/SPCE, PtNP/SPCE, and rGO–CNT/PtNP/SPCE. In addition, the PtNP/rGO–CNT/PtNP/SPCE electrode exhibited a sensitivity of 206 μA mM<sup>−1</sup>·cm<sup>−2</sup> to H<sub>2</sub>O<sub>2</sub> in a linear range of 25 to 1000 μM (<i>R</i><sup>2</sup> = 0.99). Moreover, the PtNP/rGO–CNT/PtNP/SPCE electrode was less sensitive to common interfering substances, such as ascorbic acid, uric acid, and glucose than H<sub>2</sub>O<sub>2</sub>. Finally, real-time monitoring of H<sub>2</sub>O<sub>2</sub> released from LNCaP cells was successfully performed by this electrode. Therefore, we expect that the PtNP/rGO–CNT/PtNP/SPCE can be utilized as a promising electrochemical sensor for practical nonenzymatic detection of H<sub>2</sub>O<sub>2</sub> in live cells or clinical analysis.
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