Elucidation of dissociation constants and binding sites of antibody-antigen complex using AlGaN/GaN high electron mobility transistors

In this study, we used antibody-immobilized AlGaN/GaN high electron mobility transistors (HEMTs) for detecting a short peptide, and revealing the number of binding sites of the antibody for the peptide and the dissociation constants of the antibody-peptide complex. In our case, two binding sites were found on the ferritin heavy chain (FHC) antibody and the dissociation constants of the antibody-peptide complex were 2.723×10
^-11
M and 6.994×10
^-9
M for the two binding sites, respectively. The estimated dissociation constants are consistent within the reasonable range of the IGg antibody-antigen complexes binding constants. It also reveals the limit of detection is not only decided by the performance of the transistors but also the dissociation constant of the detected molecules. To our knowledge, it is the first time that AlGaN/GaN HEMTs using on the study of protein-peptide binding affinity. The results show that AlGaN/GaN HEMTs can not only be used as biosensors, but also a good tool and platform for analytical chemistry with numerous advantages since they are label-free, low-cost, biocompatible, stable in high temperature, real-time detection. Compared with other methods and techniques investigating the binding and kinetics of biological molecules, we do demonstrate AlGaN/GaN HEMTs have great potential to compete with conventional or proposed methods.