Investigation an‎d Study of the Performance Improvement of Optical Sensors Modified with Spiky Nanostructures in Nitrate Sensing

10/19/2026 12:00:00 AM

The increase in nitrate pollution of water resources has become one of the significant environmental an‎d health challenges worldwide. To ensure compliance with regulatory limits an‎d the use of effective nitrate removal methods, continuous, real-time, an‎d on-site monitoring of its concentration is of great importance. In this regard, the development of optical sensors based on the localized surface plasmon resonance phenomenon can be considered a novel, proactive approach that offers a suitable alternative to complex, costly conventional analytical methods. In this study, aiming to investigate the effect of morphology on the optical response an‎d improve the performance of the nitrate sensor, two spherical an‎d spiky structures were compared. Gold-silver spiky nanostructures were synthesized using a seed-mediated growth method based on chemically reduced spherical gold nanoparticles modified with cysteamine. Nitrate detection was designed based on aggregation, an‎d the critical concentration of 30 μM was selec‎ted as the optimal amount of cysteamine. To optimize the spiky nanostructures for colorimetric nitrate detection, the optimal concentrations of hydrochloric acid an‎d silver nitrate were determined to be 0.2 M an‎d 3 mM, respectively. The resulting structures were characterized using UV-Vis, DLS, FE-SEM, Zeta Potential, TEM, an‎d EDAX tests. Compared to the spherical nanosensor, the spiky nanosensor offered a wider linear range of 5-350 ppm an‎d a sensitivity to nitrate 4 times higher. The detection limit of the spiky nanosensor was 4.8 ppm, which, compared to 19.5 ppm for the spherical nanosensor, showed better performance for nitrate monitoring. The spiky nanosensor exhibited excellent selec‎tivity in the presence of interfering ions. The stability test results showed a reliable an‎d functional lifespan of 9 days for the nanosensor. In addition, the reproducibility of the nanosensors was confirmed by examining five independent batches, with a coefficient of variation of 1.89%.

نيترات , حسگر نوري , تشديد پلاسمون سطحي موضعي , نانوساختارهاي تيغ‌دار , نانوذرات كروي , اصلاح سطح

Nitrate , Optical sensor , Localized surface plasmon resonance , Spiky nanostructures , Spherical nanoparticles , Surface modification

Reza Sanaei

Dr. Alireza Hemmati