Multifunctional nanocatalyst-based ultrasensitive detection of human tissue transglutaminase 2

Tissue transglutaminase 2 (TGM2) is a novel tumor marker, which can be used as the complementary marker for alpha-fetoprotein to improve overall diagnostic performance of hepatocellular carcinoma at the clinical level. In this work, we have developed a multifunctional nanocatalyst-based electrochemical method for TGM2 assay with an ultrahigh sensitivity. Here we firstly functionalize carboxyl-modified graphene oxide with poly-lysine and copper ion to form an electrochemical nanocatalyst. On the one hand, the nanocatalyst can function as the substrate of TGM2. On the other, the nanocatalyst can be applied for signal amplification to enable high sensitivity of the detection. With the specific glutamine-donor-peptide of TGM2 modified on the electrode, the exertion of the transamidation activity by TGM2 can lead to the tethering of the nanocatalyst with the peptide on the electrode, inducing obvious changes of the electrochemical signals. Therefore, simple and sensitive detection of TGM2 can be achieved. Moreover, TGM2 is also detected effectively in complex serum samples, suggesting potential diagnostic applications of the new method proposed in this work.