Silver nanoparticle-functionalized 3D flower-like copper (II)-porphyrin framework nanocomposites as signal enhancers for fabricating a sensitive glutathione electrochemical sensor

In this paper, sliver nanoparticle (Ag NP)-functionalized 3D copper (II)-porphyrin framework (MOF) nanoflowers were applied as modifiers of glassy carbon electrodes (GCEs) for catalytic oxidation and quantitative detection of glutathione (GSH). Specifically, Ag NPs could not only increase the electrical conductivity of Cu-TCPP (TCPP = tetrakis(4‐carboxyphenyl)porphyrin) MOF but also adsorb GSH. Meanwhile, the unique 3D flower-like structure of Cu-TCPP MOF provides a large number of attachment sites for Ag NP incorporation. With the assistance of the electrocatalytic ability of copper ions released from Cu-TCPP nanoflowers, the fabricated electrochemical sensor could realize sensitive determination of GSH without the addition of copper ions in the analytes. Under the optimum experimental conditions, the electrochemical behaviour of GSH was investigated through cyclic and square wave voltammetry, and a characteristic oxidation peak of the Cu(II)-GSH complex emerged ca. + 0.30 V vs. Ag/AgCl. The Ag/Cu-TCPP/GCE electrochemical sensor exhibited a wide linear dynamic range from 1.0 × 10–6 M to 1.0 × 10–4 M with a low detection limit of 6.6 × 10–8 M and presented excellent reproducibility, stability and anti-interference performance. More importantly, the constructed sensor was further expanded to quantify GSH in human serum samples with recoveries between 96.5–104.6%, providing an effective method for the trace of GSH in early disease diagnosis.