A novel bio-electrochemical sensor based on a 1,4-bis(triphenylphosphonium)butane)3[SiW11O39Ni(H2O)]/P@ERGO nanocomposite for the selective determination of l-cysteine and l-tryptophan

Abstract

Designing and developing a low-cost and highly efficient nanocomposite featuring abundant active sites with excellent transfer ability for electrons and high conductivity is critically important and challenging for the detection of biomolecules. In this study, a novel bio-sensor based on a tetra-component nanocomposite containing 1,4-bis(triphenylphosphonium)butane (BTPB), SiW₁₁O₃₉Ni(H₂O) (SiW₁₁Ni), and phosphorus-doped electrochemically reduced graphene oxide (P@ERGO) was synthesized via an electrodeposition procedure. The prepared hybrid nanocomposite (i.e., (BTPB)SiW₁₁Ni/GO) was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), and inductively coupled plasma-optical emission spectrometry (ICP-OES). The surface morphology, electrochemical, and electrocatalysis properties of the (BTPB)SiW₁₁Ni/P@ERGO/GCE were evaluated by field emission scanning electron microscopy/EDS (FE-SEM/EDS), voltammetry, amperometry, and electrochemical impedance spectroscopy (EIS). In general, the (BTPB)SiW₁₁Ni/P@ERGO/GCE-based bio-sensor exhibited satisfactory sensing performance for L-cysteine (Cys) and L-tryptophan (Trp) under optimized conditions. It showed good linearity in a wide-range of 10–2500 and 1–2000 μmol L⁻¹ and a low limit of detection (LOD) of 0.12 and 0.83 μmol L⁻¹ (S/N = 3) for Cys and Trp, respectively, via the amperometry method at the biological pH (= 7.0). Additionally, this bio-sensor showed excellent selectivity and high stability, resulting from the synergistic effect of SiW₁₁Ni, BTPB, and P@RGO. Furthermore, the practical application potential of the (BTPB)SiW₁₁Ni/P@ERGO bio-sensor was validated by detecting Cys and Trp in real samples.