Sensitive fiber-optic localized surface plasmon resonance sensor for early pancreatic cancer detection via carbohydrate antigen 19-9 and supplementary biomarkers.

Early detection of pancreatic cancer remains a major clinical challenge with the limited specificity of representative biomarker such as carbohydrate antigen 19-9 (CA19-9). CA19-9 with traditional methods including enzyme-linked immunosorbent assay (ELISA) are primarily used to monitor treatment responses and predict prognosis. This study describes the potential of CA19-9 as an indicator for early diagnosis of pancreatic cancer using a sensitive fiber-optic localized surface plasmon resonance (FO LSPR) sensor. The FO LSPR technology detected CA19-9 within 10 min, with a detection limit about 1.6 orders of magnitude lower (6.89 mU/mL) than that of ELISA. When CA19-9 was quantified in 150 samples, a Pearson correlation coefficient of 0.937 was demonstrated using ELISA, and our sensor better distinguished early patients from healthy controls. FO LSPR uncovered subtle right-skewed gradients of CA19-9 within the normal range that were undetectable by ELISA. The sensitivity for >99 % specificity and the area under the curve for the discrimination of patients and healthy individuals improved to 0.692 and 0.936, respectively, compared with those of ELISA (0.515 and 0.893, respectively). These results mean that FO LSPR liquid biopsy helps identify new roles of CA19-9 in pancreatic cancer diagnosis. Moreover, using FO LSPR measurements of two supplementary markers, apolipoprotein A1 and interleukin 8, the diagnostic power was improved, with statistically significant differences from that obtained using CA19-9 alone, specifically for the discrimination of early pancreatic ductal adenocarcinoma. In conclusion, the FO LSPR system provides a simple, rapid, and reproducible analytical platform that overcomes key limitations of conventional immunoassays.