Enhanced multi-colorimetric sensor based on silver triangular nanoplates for rapid and sensitive vitamin C detection

Colorimetric sensors have emerged as promising alternatives for vitamin C detection due to their simplicity, speed, and ease of use. However, conventional single-color indicators often suffer from limited sensitivity and are challenging for naked-eye detection. This study presents a simple, rapid, and reliable multi-colorimetric method for vitamin C detection using silver triangular nanoplates (AgTNPs) as the sensing platform. By investigating the effect of varying potassium chloride (KCl) concentrations (2, 4, 8, and 10 mM), the results reveal that an optimal KCl concentration of 8 mM significantly enhances the sensor's performance. The enhanced sensor achieved a high sensitivity of 4.57 nm/μM ± 0.35 nm/μM with a correlation coefficient of 96 %, and lowest LOD was 0.52 μM enabling accurate quantification of vitamin C across a concentration range of 0–40 μM. Furthermore, the sensor demonstrated an ultra-fast response time (as low as 27 s), making it suitable for real-time applications. To further improve usability, a novel visual detection approach using Euclidean distance ($d$) analysis was introduced, facilitating direct visual observation of vitamin C concentrations. The sensor achieved Euclidean distance values exceeding 0.020 units for vitamin C concentrations above 20 μM, providing a clear and distinguishable color change visible to the naked eye. These findings establish the enhanced AgTNP-based colorimetric sensor as a highly effective tool for vitamin C detection in food samples, offering a practical solution for quality control and nutritional analysis.