Reflective interference study of binding nikelions on nitrilotriacetic (nta) nanoporous alumina chips for detections of his-tagged proteins

Abstract

In this report, the application of a label-free reflectometric interference spectroscopy (RIfS) using nanoporous anodic aluminium oxide (AAO) to study of binding kinetics of nickel ions to self-assembled monolayers (SAMs) of nitrilotriacetic (NTA) chelates is presented. Highly ordered nanoporous AAO fabricated by electrochemical anodization of aluminium foil was used as the RIfS sensing platform. SAM of alkanethiol (C2) terminated with NTA functional group that specifically binds to Ni2+ ions was covalently attached to gold coated AAO surface using simple self-assembly process. The binding of Ni2+ ions to NTA-Au-AAO chip using different concentrations (0.1 mM to 100 mM) was monitored by RIfS spectroscopy in a steady state conditions. Our results show that RIfS optical system using functionalised nanopore AAO arrays is capable of detecting real-time binding and binding kinetics of Ni2+ ions on NTA ligands. This optical method shows a great promise to be used as generic method for studying molecular binding kinetics for other analytes including metal ions, proteins, DNA and antibodies. Furthermore, the approach can be easily translated into a rapid and cost-effective biosensing device for the detection and purification of histidine tagged genetically engineered proteins relevant to proteomics.