In this study, antibody-immobilized AlGaN/GaN high electron mobility transistors (HEMTs) were used for detecting a short peptide, and revealing the number of binding sites of the antibody (protein) for the peptide and the dissociation constants of the antibody-peptide (protein-peptide) complex. Two binding sites were found on this antibody and the dissociation constants of the antibody-peptide complex were 2.723x10-11M and 6.994x10-9M 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. Compared with other methods and techniques investigating the binding affinity and kinetics of biological molecules, we do demonstrate AlGaN/GaN HEMTs have a great potential to compete with conventional or proposed methods.

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