A sandwich-type label-free electrochemiluminescence immunosensor for neurotensin based on sombrero model with graphene-hyaluronate-luminol composite

An ultrasensitive sandwich-type label-free electrochemiluminescence (ECL) immunosensor based on sombrero model for the detection of neurotensin (NT) in human serum and urine was developed. Graphene-hyaluronate-luminol (G-HY-luminol) composite was coated on the surface of the glassy carbon electrode to build the ECL immunosensor, which gave in-situ ECL signals by luminol. A secondary NT unlabelled antibody was used to form the final sandwich immunocomplex as a sombrero model, facilitating reduction of the ECL intensity to improve the sensitivity of detection significantly. Results showed that the inhibition of ECL intensity increased with the logarithm of NT concentration within a wide linear range from 0.001 pg cm−3 to 100 pg cm−3. In addition, specificity, stability, reproducibility, regeneration and application were satisfactory. Therefore, this developed ECL immunosensor has a potential for practical detection of NT and NT-like peptides with small molecular weight in the clinical diagnostics.