Creatinine-induced specific signal responses and enzymeless ratiometric electrochemical detection based on copper nanoparticles electrodeposited on reduced graphene oxide-based hybrids

In this article, a novel and efficient electrochemical sensor of creatinine was facilely constructed on the surface of multifunctional nanohybrids-modified glassy carbon electrode (GCE), integrating creatinine-induced specific signal response and enzymeless ratiometric signal detection strategy. Dopamine hydrochloride as a reducing agent was dispersed in interface layers of graphene oxide. One-step hydrothermal reaction of graphene oxide with dopamine hydrochloride was conducted to prepare reduced graphene oxide (rGO), together with self-polymerization of polydopamine (PDA) attaching on rGO. Nile blue (NB) was loaded on rGO under ultra-sonication through pi-pi stacking interactions between rGO and NB. The resulting PDA-rGO-NB complex was drop-coated on the surface of GCE. Under cyclic voltammetry scanning, copper nanoparticles (CuNPs) were prepared through electrochemical reduction of Cu2+ ions and electrodeposited on PDA-rGO-NB surface to construct a new CuNPs/PDA-rGO-NB/GCE sensing platform. Specific interactions of creatinine with Cu2+ ions from CuNPs surface led to regularly decreased peak current intensities located at -0.05 V (ICu2+) and negligible changes in peak current intensities located -0.325 V from NB (I-NB). There was a well plotted linear relationship between ICu2+/I-NB and creatinine concentration in the range from 0.01 to 100 mu M, with a low detection limit of 2 nM. This sensing platform enabled highly sensitive and selective responses towards creatinine, over potential interferents. In practical samples, this developed enzymeless ratiometric electrochemical sensor realized efficient detection of creatinine, showing high detection performance.