Clinically comparable impedimetric immunosensor for serum alkaline phosphatase detection based on electrochemically engineered Au-nano-Dendroids and graphene oxide nanocomposite

In this work, we demonstrate label-free electrochemical impedance spectroscopy (EIS) based alkaline phosphatase (ALP) detection using gold nanoparticles (AuNPs), electrochemically engineered Au-nano-Dendroids, and graphene oxide (GO) nanocomposite. These nanomaterials were sequentially deposited on to the screen-printed carbon electrode (SPCE) and antibodies against ALP (anti-ALP) were immobilized using carbodiimide bioconjugation process. The sensor probe has been characterized extensively using TEM, EDX, SAED, XRD, FESEM, FTIR, DIC, and electrochemical techniques. The analytical performance of fabricated biosensor has been evaluated using EIS, where linear dynamic range and limit of detection were obtained to be 100-1000 U/L and 9.10 (+/- 0.12) U/L, respectively. The developed biosensor showed high selectivity towards ALP with negligible interference (k(sel) << 1; n = 3) due to coexisting molecules. The sensor probe has successfully recovered ALP between 108.84% and 172.50% (n = 3) in human serum samples. The sensor has been used to estimate ALP in clinical serum samples, where the level was found to be 83.15 U/L and was comparable with standard technique used in the hospitals. The shelf life, stability, and reproducibility have also been evaluated.