Alkaline phosphatase detection using electrochemical impedance of anti-alkaline phosphatase antibody (Ab354) functionalized silicon-nanowire-forest in phosphate buffer solution

•This study presents an electrochemical method for Alkaline Phosphatase (ALP) detection based on anti-ALP functionalized Si nanowire platform.•The ability to sense between different concentrations of ALP has been demonstrated.•The detection limit of 1 nM is one of thelowest demonstrated by electrochemical methods and the lowest demonstrated by impedancespectroscopy.•Control and specificity measurements prove that blocking exists, and excellent specificity was achieved.•Highly reproducibility of the system was achieved. This article presents an electrochemical impedance study on the detection of Alkaline Phosphatase (ALP) in phosphate buffer saline (PBS) solution by using anti-ALP functionalized Si nanowires (SiNWs). Electrochemical impedance was measured using a three-electrode cell where the working electrode was a very dense and highly disordered array of Si NWs, e.g. SiNW-forest. This array was grown using plasma enhanced chemical vapor deposition (PECVD) at 350 °C. The NW surface was modified by immobilizing the anti-ALP. A very efficient detection of very low ALP concentrations in PBS solution, ranging from 0.03 U/L to 0.3 U/L (1 nM–10 nM respectively), as well as a high selectivity due to the antibody/antigen interaction were demonstrated. The remarkable sensitivity and selectivity achieved through the combination of SiNW-forest combined electrochemical impedance spectroscopy suggest an effective strategy for real time and quantitative sensing of ALP.