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A facile and sensitive approach is introduced to precisely determine trace amounts of prostate specific antigen (PSA) by gold nanostructures deposited on fluorine-doped tin oxide (FTO) electrodes. The gold electrode fabrication is carried out by integration of two techniques of vacuum-deposition and electrochemical growth. The electrode was successfully used as a label-free immunosensor for PSA determination in human serum samples. The dependency of the biosensor performance on various fabrication parameters have been investigated and the optimized fabrication rout has been specified. This label-free immunosensor presents a noticeable performance with a large range of linearity from 0.05 to 30 ng/mL, a low detection limit of 5.7 pg/mL, and a long-term stability of 4 weeks. The obtained results for PSA determination in real samples show a good agreement with ELISA results with less than 10% deviation. [ABSTRACT FROM AUTHOR]

A new approach has been developed to improve sensing performances of electrochemically grown Au nanostructures (AuNSs) based on the pre-seeding of the electrode. The pre-seeding modification is simply carried out by vacuum thermal deposition of 5 nm thin film of Au on the substrate followed by thermal annealing at 500 °C. The electrochemical growth of AuNSs on the pre-seeded substrates leads to impressive electrochemical responses of the electrode owing to the seeding modification. The dependence of the morphology and the electrochemical properties of the AuNSs on various deposition potentials and times have been investigated. For the positive potentials, the pre-seeding leads to the growth of porous and hole-possess networks of AuNSs on the surface. For the negative potentials, AuNSs with carved stone ball shapes are produced. The superior electrode was achieved from AuNSs developed at 0.1 V for 900 s with pre-seeding modification. The sensing properties of the superior electrode toward glucose detection show a high sensitivity of 184.9 µA mM−1 cm−2, with a remarkable detection limit of 0.32 µM and a wide range of linearity. The excellent selectivity and reproducibility of the sensors propose the current approach as a large-scale production route for non-enzymatic glucose detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • We have fabricated nickel-gold bimetallic nanostructures by a novel method. • The Ni/Au@FTO electrodes provide a high stability for glucose determination. • These electrodes show a good glucose sensitivity of 893 μA mM−1 cm−2. • The low detection limit for glucose determination is 0.7 μM. • The fabrication procedure proposes excellent reproducibility. Bimetallic nanostructured electrodes are promising candidates for non-enzymatic glucose detection due to their excellent selectivity and high sensitivity. In this work, a bimetallic Ni/Au non-enzymatic glucose sensor was developed by the electrodeposition of nickel nanostructures on Au nanoparticles (NP). Physical vapor deposition followed by thermal annealing was used for the growth of seeding Au (NP) on fluorine doped tin oxide (FTO) substrates. The electrochemical growth of Ni nanostructures on the Au-seeded substrates led to enhanced electrochemical responses from the modified electrodes. Cyclic voltammetry results showed considerable improvement of the electrocatalytic activity of the Ni/Au bimetallic structure in comparison to monolithic Ni and Au structures due to the synergistic effect. The sensor showed two linear ranges of 5 μM–3.5 mM and 3.5–7 mM for glucose detection with the sensitivity of 893 (μA mM−1 cm−2). The low detection limit of 0.7 μM and the fast response time of 5 s was achieved. The selectivity, reproducibility and accuracy of the fabricated sensor in determination of human serum glucose suggest its potential for large-scale production as commercial non-enzymatic glucose detection. [ABSTRACT FROM AUTHOR]