MC-Au/MSS-Z8 porous network assisted advanced electrochemical immunosensing of 25-hydroxyvitamin D3

On-site monitoring of vitamin D levels is subject matter of immediate attention owing to the serious aftermath of its long standing deficiency. Therefore, a novel and efficient voltammetric immunosensing of 25-hydroxyvitamin D3 (25(OH)VD3) has been experimented based on an advanced sensing platform composed of meso-microporous silica-zeolitic imidazolate framework-8 (MSS-Z8) with highly enhanced surface area (SBET, MSS-Z8 (643.4 m2g-1) > SBET, MSS (49.95 m2g-1)), embedded with gold particles (mass loading of 82 μg), particularly of microcubic morphology (MC-Au). Further, the MC-Au/MSS-Z8/FTO platform was fashioned with antibody specific to 25(OH)VD3 via interaction between Au and abundant –SH groups present on the antibody surface. After optimization of operational parameters, the Ab/MC-Au/MSS-Z8/FTO immunosensor was employed for the determination of 25(OH)VD3 within 0.01–106 pg mL−1 concentration range through differential pulse voltammetry technique in [Fe(CN)6]3-/4-. Thus, 0.01 pg mL-1 concentration of 25(OH)VD3 was the experimental limit of detection of the immunosensor. Further, upon examination of various analytical parameters, it turns out that the immunosensor exhibited low theoretical LOD (0.23 pg mL−1) and LOQ (0.76 pg mL−1), wide linear range (0.01–106 pg mL−1), ultra-sensitivity (143.9 μA [log (pg mL−1)]−1 cm−2), adequate reproducibility (RSD ≤1.23%) and acceptable shelf life. Most importantly, the immunosensor presented proficient performance with spiked human serum samples (Recovery = 97.20–100.7%, RSD value < 5.6%), evincing the adequacy of present biosensing approach.