One-step electrochemically co-assembled redox-active [Ru(bpy)2(tatp)]2+–BSA–SWCNTs hybrid film for non-redox protein biosensors

A redox-active [Ru(bpy)2(tatp)]2+–BSA–SWCNTs (bpy=2,2′-bipyridine, tatp=1,4,8,9-tetra-aza-triphenylene, BSA=bovine serum albumin, SWCNTs=single-walled carbon nanotubes) hybrid film is fabricated on an indium–tin oxide (ITO) electrode via one-step electrochemical co-assembly approach. BSA is inherently dispersive and therefore served as the linking mediator of SWCNTs, which facilitate the redox reactions of [Ru(bpy)2(tatp)]2+ employed as a reporter of BSA. The evidences from differential pulse voltammetry, cyclic voltammetry, scanning electron microscope, emission spectroscopy and fluorescence microscope reveal that the [Ru(bpy)2(tatp)]2+–BSA–SWCNTs hybrid can be electrochemically co-assembled on the ITO electrode, showing two pairs of well-defined Ru(II)-based redox waves. Furthermore, the electrochemical co-assembly of the [Ru(bpy)2(tatp)]2+–BSA–SWCNTs hybrid is found to be strongly dependent on the simultaneous presence of BSA and SWCNTs, indicating a good linear response to BSA in the range from 6 to 50 mg L−1. The results from this study provide an electrochemical co-assembly method for the development of non-redox protein biosensors.

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► A [Ru(bpy)2(tatp)]2+–BSA–SWCNTs film is co-assembled on ITO electrodes.
► The hybrid film shows two pairs of well-defined Ru(II)-based redox waves.
► The presence of BSA-linked SWCNTs promotes electrochemical assembly of [Ru(bpy)2(tatp)]2+.
► The BSA sensor shows a good linear response between 6 and 50 mg L−1.