Single nanoparticle analysis for homogeneous immunoassay of CA19-9 for serological evaluation

Abstract

Pancreatic cancer is a malignant tumour with high mortality. Surgery after diagnosis at the early stage is the most effective treatment. As the most effective biomarker of pancreatic cancer, CA19-9 has important clinical significance for both early diagnosis and surgical prediction. Herein, a single nanoparticle homogeneous immunoassay based on Au nanoparticle tagging was proposed for CA19-9 determination, with a dynamic range from 6.25 to 400 U mL⁻¹ in intensity mode and 6.25 to 100 U mL⁻¹ in frequency mode. The limits of detection were 0.72 U mL⁻¹ (intensity mode) and 0.84 U mL⁻¹ (frequency mode). Accurate results were obtained without any washing and separation procedure, and the matrix effect was avoided by monitoring both the intensity and frequency signal obtained from single nanoparticles. The method was successfully applied to the serological evaluation of patients. The results were well correlated with those measured by conventional clinical methods, demonstrating a promising foreground in the preoperative assessment of resectability and evaluation of disease recurrence.