Carbon-based electrode loaded with Y-doped SrTiO3 perovskite as support for enzyme immobilization in biosensors

Many studies have been presented Y-doped SrTiO3 as a potential alternative material for electrical, electrochemical and chemical applications due to its mixed (ionic and electronic) conduction and its morphological characteristics. In this work, 8% mol yttrium doped SrTiO3 (YST08) was used to assemble a Horseradish peroxidase (HRP) biosensor aiming at hydrogen peroxide (H2O2) detection. The perovskite was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller N2 physisorption (BET), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS); and, after HRP immobilization, by zeta potential, atomic force microscopy (AFM), cyclic voltammetry, Fourier-transform infrared spectroscopy (FTIR), and chronoamperometry. The structure presented a low specific surface area due to particle agglomeration as a result of the elevated temperature of calcination. This characteristic was ratified by SEM analysis, which also demonstrated regular and well-rounded grains. Zeta potential results suggest successful HRP immobilization on YST08 surface because of the resemblance of zeta potential of immobilized sample and free HRP. FTIR spectra and AFM micrographs confirm a homogenous HRP adsorption due to functional groups identification and surface topography changes. YST08 + HRP electrode proved to be efficient in sensing H2O2 in different scan rates and background electrolytes under electrochemical evaluation. Results also showed that the process is surface-controlled, exhibiting a low reduction potential for H2O2 around −0.31 V at pH = 7. The YST08 matrix was effective to the diffusion mechanisms presenting a detection limit of 14.97 μM; and increases the enzyme long-term activity, retaining 14.97% of specific capacity after 180 days.