Electrochemical immuno determination of connective tissue growth factor levels on nitrogen-doped graphene

Connective tissue growth factor (CTGF) is a disease marker of rheumatoid arthritis (RA), and its rapid and sensitive detection is essential for the diagnosis of RA. In this work, a three-dimensional pore structure of alkali-activated nitrogen-doped graphene (aN-G) was used as an electrode modification material, and a label-free electrochemical immunosensor for the sensitive detection of CTGF was successfully constructed by the formation of an amide bond between amino groups in protein and carboxyl groups on the carbon surface. Under optimized conditions, the sensor achieved accurate detection of CTGF in the wide range of 0.0625 ~ 2000 pg mL^-1. It had good accuracy (95.0 ~ 100.1%), repeatability (1.2 ~ 2.2%), stability, selectivity, and a low limit of detection (0.0424 pg mL^-1, S/N = 3). The sensor was used in serum samples of patients with RA, and CTGF was also successfully detected. Based on this, the electrochemical sensor is expected to become an effective method for RA diagnosis and treatment effect evaluation.