Label-Free Silver Nanoparticles for Colorimetric Determination of Gatifloxacin

The development of a simple, sensitive, and in situ colorimetric determination strategy based on a label-free probe for accurate and sensitive gatifloxacin detection is highly desirable. Herein, a novel label-free ratiometric sensor was fabricated using silver nanoparticles (AgNPs) stabilized by trisodium citrate for the sensitive detection of gatifloxacin. The prominent alterations in the resonance absorption of AgNPs occurred after the addition of gatifloxacin, making it possible to establish a relationship between the A ₅₁₉ /A ₃₉₈ ratio of AgNPs and the concentration of gatifloxacin. Under optimal conditions, the detection linearity of gatifloxacin was from 0.01 to 13 μg/mL with a low detection limit of 0.008 μg/mL (3σ/slope). The color of AgNPs gradually deepened with increasing gatifloxacin concentration, which could be clearly distinguished with the naked eye at a gatifloxacin concentration of 3.5 μg/mL. The label-free AgNPs detection system holds potential for simple, accurate, and rapid colorimetric detection of gatifloxacin in complex biological samples, offering a new perspective for the fabrication of ratiometric sensor platforms.