Acceleration effect of copper(II) ions on the rate of citrate synthesis of gold nanoparticles

Electrochemical detection of hepcidin based on spiegelmer and MoS2NF-GNR@AuNPs as sensing platform

Spiegelmers, mirror image L- RNA oligonucleotides, possesses high plasma stability and non-immunogenicity. Herein, a novel spiegelmer based impedimetric biosensor grafted with Au nanoparticles and molybdenum disulfide nanoflowers/graphene nanoribbons nanocomposite has been designed to detect hepcidin in spiked-in human serum sample. Firstly, molybdenum disulfide nanoflowers/graphene nanoribbons (MoS₂NF-GNR) hybrid was drop-casted onto the FTO electrode followed by electro deposition of Au nanoparticles (AuNPs). Hepcidin specific thiolated spiegelmer was then immobilized on the MoS₂NF-GNR@AuNPs for hepcidin detection. Electrochemical impedance spectroscopy was used to assess the performance of the sensing platform based on the variation of charge transfer resistance (ΔR_ct) relative to the Fe(CN)₆^4-/3- electrochemical probe in the presence of hepcidin. The impedance signals were recorded at the frequency range of 10^-1 to 10⁵ Hz and potential was set as 0.18 V. Under optimized conditions, the limit of detection of spiegelmer based sensor for hepcidin was 0.173 pgmL^-1 within a wide linear range of 0.005-10 ngmL^-1. The biosensor possesses selectivity, acceptable reproducibility with RSD as 4.76% and stability for up to 20 days. The satisfactory recovery result (89.8-103.1 %) in human serum indicates that the sensor has applicability in clinical monitoring of hepcidin.