# A Simple and Visual Colorimetric Aptasensor Based on AuNPs for the Rapid Detection of Sulfamethazine in Environmental Samples

## TL;DR

This paper presents a simple and visual method to detect sulfamethazine in environmental samples using gold nanoparticles and an aptamer.

## Contribution

A novel AuNP-based colorimetric aptasensor is developed for rapid and visual detection of sulfamethazine in environmental samples.

## Key findings

- The aptasensor has a wide linear range of 0.05 to 0.4 µg/mL and a detection limit of 0.039 µg/mL.
- Molecular dynamics simulations confirmed stable aptamer-SMZ binding, ensuring high selectivity.
- Spike-and-recovery experiments showed high accuracy and good agreement with HPLC results.

## Abstract

Sulfamethazine (SMZ) is widely used in livestock production, and its residues can enter water and soil environments, posing potential risks to human health and ecosystems. This study focuses on environmental samples and constructs an AuNP-based colorimetric aptasensor using the SMZ1S aptamer for the rapid visual detection of SMZ. Under optimized conditions, the aptasensor showed a wide linear range from 0.05 to 0.4 µg/mL and a limit of detection of 0.039 µg/mL. Molecular dynamics simulations have demonstrated that the aptamer’s binding to SMZ is stable, providing a theoretical basis for the high selectivity of the aptasensor. Spike-and-recovery experiments yielded recoveries of 87.3–105.5%, 88.6–102.8%, and 87.5–103.4% for SMZ in lake water, tap water, and soil samples, respectively, with relative standard deviations of 5.9–8.3%, 8.0–10.6%, and 4.8–9.6%, showing good agreement with high-performance liquid chromatography (HPLC) results (R2 ≥ 0.981). Overall, the proposed aptasensor provides a simple and effective approach for rapid detection of SMZ in environmental samples.