# Supramolecular PDDA/PEDOT:PSS Biosensor for Early Pancreatic Cancer Detection via CA19-9: Clinical Validation on Human Blood Samples

## TL;DR

A new biosensor was developed and tested for early detection of pancreatic cancer by measuring the biomarker CA19-9 in blood samples.

## Contribution

The study introduces a novel capacitance-based biosensor with high sensitivity and selectivity for early pancreatic cancer detection.

## Key findings

- The biosensor achieved a detection limit of 0.01 U/mL and quantification limit of 0.03 U/mL for CA19-9.
- The device showed good performance in blood samples from patients at different stages of pancreatic cancer.
- Statistical analyses confirmed the biosensor's reliability and potential for clinical use.

## Abstract

Pancreatic cancer has one of the highest mortality rates,
and early
detection remains a challenge, significantly limiting therapeutic
strategies. In this study, we present the clinical validation of a
novel multilayered capacitance-based biosensor for early pancreatic
cancer detection. Poly­(diallyldimethylammonium chloride) and (poly­(3,4-ethylenedioxythiophene):polystyrenesulfonate)
(PDDA/PEDOT:SS) were physically adsorbed onto gold interdigitated
electrodes via self-assembly, followed by surface functionalization
with CA19-9 antibodies. Upon selective binding of the CA19-9 biomarker,
the adsorption kinetics indicated that the system reached equilibrium
within 7 min. Polarization modulation infrared reflection absorption
spectroscopy, atomic force microscopy analysis, and electrical measurements
confirmed the successful functionalization of the biosensor surface.
The interaction between CA19-9 and the functionalized surface was
evaluated using electrical impedance spectroscopy. The calibration
curve was best fitted to the Langmuir–Freundlich model, and
all data sets were processed by visual analysis (IDMAP). Key characteristics
of the devices  sensitivity and selectivity  demonstrate
a limit of detection of 0.01 U/mL, limit of quantification of 0.03
U/mL, and specificity toward CA19-9. Analyses were conducted on 24
blood samples collected from patients at different stages of the disease.
The good performance at low and moderate CA19-9 concentrations was
supported by IDMAP and Bland–Altman statistical analysis. The
results confirmed the biosensor’s potential as an innovative,
sensitive, and selective tool for early detection of pancreatic cancer,
with the possibility of future technology transfer to the Brazilian
Health System.