# Flower-like Silver Bismuth Sulfide/Carbon Nanosphere Nanocomposite for Sensitive Electrochemical Tumor Marker Sensing

## TL;DR

A new portable sensor using a nanocomposite material detects cancer biomarkers with high sensitivity and accuracy.

## Contribution

A novel AgBiS2/CNS nanocomposite improves electrochemical sensing of CEA with enhanced sensitivity and practical applicability.

## Key findings

- The sensor achieved a detection limit of 7.6 ng mL–1 for carcinoembryonic antigen (CEA).
- Human serum samples showed recovery rates between 98.06% and 99.69%, confirming practical applicability.
- The nanocomposite improved aptamer immobilization, enhancing sensor stability and reproducibility.

## Abstract

A portable electrochemical
aptasensor was fabricated
using a nanocomposite
(Silver Bismuth Sulfide/Carbon Nanosphere, AgBiS2/CNS)
for the targeted detection of the cancer biomarker carcinoembryonic
antigen (CEA). The prepared nanocomposite provides a higher specific
surface area, electrical conductivity, and tunable functionality,
which enable more effective aptamer immobilization compared to conventional
electrode materials. The aptamer, known for its chemical stability
and robust surface binding, was immobilized on the surface-treated
screen-printed carbon electrode (SPCE), thereby enhancing the reproducibility
and stability of the sensor platform. The fabricated portable sensor
demonstrated the ability to detect CEA in an early stage with high
sensitivity and selectivity. Quantification and optimization were
performed using electrochemical impedance spectroscopy (EIS), cyclic
voltammetry (CV), and differential pulse voltammetry (DPV) in 0.05
M phosphate buffer solution (PBS, pH 7.0) with 0.1 M KCl [Fe­(CN)6]3–/4– (5 mM) electrolyte system.
The lower limit of detection (LOD) for CEA was found to be 7.6 ng
mL–1. Practical applicability was confirmed by evaluating
human serum samples, achieving recovery rates in the range of 98.06%
to 99.69%.