Amine Functionalized Noble Metal: Metal Oxide Nanohybrid for Efficient Electrochemical Determination of 25-Hydroxy Vitamin-D₃ in Human Serum

Abstract

Quantification of 25-hydroxy vitamin-D3 (25-OHVD3) is important because its deficiency is related to numerous diseases, including osteoporosis, depression, diabetes, heart disease, certain autoimmune conditions, and even Covid-19. In the present study, noble metal-metal oxide nanohybrid based on L-cysteine functionalized gold decorated zirconia nanoparticles (Cys-Au@ZrO2 NPs) were synthesized with the objective of enhanced electrochemical behavior, stability, availability of functional group to covalently bind with biomolecules, and developing an efficient immunosensor for 25-OHVD3 detection. The formation of Au@ZrO2 NPs and further Cys functionalization was validated by various characterizations. Cys-Au@ZrO2 NPs were electrodeposited onto ITO substrate and further modified with antibodies specific to 25-OHVD3 (ab-25VD3) and bovine serum albumin (BSA) to build an immunosensing platform for 25-OHVD3 detection. The fabricated BSA/ab-25VD3/Cys-Au@ZrO2/ITO immunosensor demonstrated an improved sensitivity of 2.01 μA ng−1 ml cm−2, LOD of 3.54 ng ml−1 for the linear detection range of 1–50 ng ml−1 with regression constant of 0.98. Moreover, the analytical performance of the BSA/ab-25VD3/Cys-Au@ZrO2/ITO immunosensor in determining 25-OHVD3 in human serum samples collected from four healthy people yielded satisfactory results that were highly correlated with the conventional enzyme-linked immunosorbent assay (ELISA).

ASu@MNPs-based electrochemical immunosensor for vitamin D3 serum samples analysis

“…Therefore, for the best of our knowledge, our work presents the higher number of serum samples analyzed than any other experimental electrochemical immunosensor available in literature and, among the validated ones, the one exhibiting the lower limit of detection. MPA/Au DPV 20-200 ng ml −1 10 ng ml −1 0.16 A ml ng −1 cm-2 [6] CAEF/RCP* Chronoamperometry 10 -100 ng ml −1 10 ng ml −1 0.16 μA ml ng −1 cm −2 [40] nCeO2/CC** DPV 1-200 ng ml −1 4.63 ng ml −1 2.08 μA ml ng −1 cm −2 [41] Cys-Au@ZrO2/ITO DPV 1-50 ng ml −1 3.54 ng ml −1 2.01 μA ml ng −1 cm −2 [42] CD-CH***/ITO DPV 10-50 ng ml −1 1.35 ng ml −1 0.2 μA ml ng −1 cm-2 [43] Asp-Gd2O3NRs/ITO DPV 10-100 ng ml −1 0.10 ng ml −1 0.38 μA ml ng −1 cm-2 [11] Fe3O4-PANnFs/ITO DPV 10-100 ng ml −1 0.12 ng ml −1 0.90 μA ml ng −1 cm-2 [10] CYM@AuMNPs DPV 7.4 -70 ng ml −1 2.4 ng ml −1 0.55 μA ml ng −1 cm-2…”

An Antibody-Free, Silver-Silver Oxide-Carbon Nanotube Nanocomposite-Based Impedimetric Sensor for the Nanomolar Detection of 25-Hydroxyvitamin D3

“…Existing work mostly utilizes the antigenantibody binding approach for sensing or employs costly catalysts such as Au, Pd etc. 5,[7][8][9] An economically viable and stable point-ofcare sensor would require a detection platform free of enzymes, antibodies, and aptamers. Also, almost all of the existing work focuses on Vitamin D as the analyte instead of 25OHD.…”

“…7 However, the focus has been mainly on D 3 as it was found to be more potent and effective than D 2 . 9 Vitamin D sensors also suffer from electrode fouling caused by strongly adsorbed oxidation products.…”