Voltammetric detection of vitamin D employing Au-MoS2 hybrid as immunosensing platform

Abstract

A voltammetric immunosensor based on molybdenum sulphide (MoS 2 ) and gold nanoparticles (Au NPs) for the determination of 25-hydroxy vitamin D 3 (25(OH)D 3 ) is reported. Anti-vit D (Ab-25(OH)D 3 ) was immobilized onto the cysteamine-modified MoS 2 and Au NPs which were deposited onto a fluoride tin oxide (FTO) electrode (Ab/Cys/Au/MoS 2 /FTO). The MoS 2 sheets were prepared by hydrothermal method followed by an in situ growth of Au film onto the MoS 2 /FTO surface. Self-assembled monolayer (SAM) of cysteamine was synthesized onto the Au/MoS 2 /FTO which acts as a linker to covalently bind Ab-25(OH)D 3 . The Ab-25(OH)D 3 -immobilized Cys/Au/MoS 2 /FTO was used to detect 25(OH)D 3 using differential pulse voltammetry. The electrochemical system provided an anodic peak current at a potential of +0.21 V vs. Ag/AgCl (satd. KCl) of ferricyanide/ferrocyanide redox couple. The detection principle relies on the inhibition of electron transfer at the electrode surface owing to the hindrance caused by the formation of immune complex between Ab-25(OH)D 3 and 25(OH)D 3 . The immunosensor shows linear response from 1 pg mL −1 to 100 ng mL −1 25(OH)D 3 and a sensitivity of 189 μA [log (pg mL −1 )] −1 cm −2 along with a low limit of detection (LOD) of 0.38 pg mL −1 . The immunosensor is highly selective towards 25(OH)D 3 and presented a long shelf life of 28 days. Also, the immunosensor exhibits satisfactory performance towards spiked human serum samples with recovery between 95.1 and 102% (RSD 1.15-3.22%).

Cu2O/MXene/rGO Ternary Nanocomposites as Sensing Electrodes for Nonenzymatic Glucose Sensors

“…From this response, the glucose concentration was determined and is tabulated in Table S3. This shows that the recovery rate 44 for each addition of glucose ranged from 97.5 to 105.2% with an RSD of 1.9−3.7%. This indicates that the prepared ternary composite is suitable for real-time biological sample analysis.…”

“…A linear relationship was observed for both currents, indicating that the electrode modified with MGA-75 exhibited a diffusion-type electron transfer process . From the linear plot, the slope value of the modified electrode was used to determine the active surface area using the Randles–Sevcik equation …”

“…42 From the linear plot, the slope value of the modified electrode was used to determine the active surface area using the Randles−Sevcik equation. 44 The determined active surface area of the modified electrode is on the order of 0.131 cm 2 (MGA−Cu 2 O) > 0.041 cm 2 (MG−Cu 2 O) > 0.03 cm 2 (M−Cu 2 O) > 0.025 cm 2 (Cu 2 O) > 0.01 cm 2 (GCE). A 3D assembly of MXene and rGO leads to an enhancement of the electrochemically active surface area as compared to the others.…”

Electrochemical studies of biofunctionalized MoS2 matrix for highly stable immobilization of antibodies and detection of lung cancer protein biomarker

“…The sensitivity of the immunoelectrode can be calculated here to be 3.35 mA ng À1 mL cm À2 by dividing the slope of the calibration curve by the electroactive surface area calculated for the BSA/anti-NSE/CS/MoS 2 /ITO immunoelectrode. 37 The lowest concentration that can be detected for NSE using the prepared immunoelectrode is 0.1 ng mL À1 . 100 ng mL À1 .…”

Advances in electrochemical sensors based on nanomaterials for the detection of lipid hormone

“…It is less destructive to its biomolecular activity, thus improving the sensitivity of detection. Kaur et al (2021) designed a voltammetric immunosensor based on molybdenum sulfur MoS 2 /AuNPs/ tin fluoride oxide with 25(OH)D 3 as the target molecule The result showed that the MoS 2 -modified AuNPs model demonstrated excellent detection conductivity, sensitivity and stability.…”