Electrochemical sensor for rapid diagnosis and early-stage detection of pancreatic cancer using Er-GQDs decorated MoS2 nanoflowers

In this study, for the first time, the erbium-doped graphene quantum dots (Er-GQDs) were decorated onto a three-dimensional MoS2 nanoflower (EGM) for electrochemically sensitive and selective detection of carbohydrate antigen, CA 19-9, in phosphate buffer saline (PBS) and biological fluids. The MoS2 nanoflowers (MoS2 NF) were hydrothermally prepared at 200 ℃ for 24 h, and then 2 – 8 nm of Er-GQDs were uniformly deposited onto 200 nm MoS2 NF. The MoS2 NF has a high electric conductivity for electrochemical performance, whereas Er-GQDs act as an effective anchor with anti-CA19-9 antibodies (CA19-9 Ab) for ultra-selectivity to CA19-9 antigen. The SPE||EGM/Ab immunosensor has substantial benefits by providing a long-lasting, ultra-sensitive, and highly selective platform for CA19-9 antigen detection. The dynamic ranges in PBS, human serum, and saliva are 5×10−5 – 250, 5×10−4 – 250, and 3×10−4 – 250 U mL−1, respectively, with limits of detection (LODs) of (0.18 − 2.95) ×10−4 U mL−1. Furthermore, the SPE||EGM/Ab immunosensor can detect CA19-9 in human serum with a recovery of 97 – 108%. The non-invasive detection of CA19-9 in saliva is stably sensitive before and after 1 h of breakfast. Moreover, the SPE||EGM/Ab immunosensor has excellent selectivity toward CA19-9 over the other 17 interferences. Results elaborate that the SPE||EGM/Ab immunosensor is a promising electrochemical biosensing probe for detecting CA19-9 in human serum and saliva for clinical diagnosis and prognosis of pancreatic cancer in the early stage.