Fluorescent Nanoprobe Utilizing Tryptophan-Functionalized Silver Nanoclusters for Enhanced Gemcitabine Detection: Optimization and Application in Real Samples

A new “signal-off” probe based on silver nanoclusters modified with tryptophan amino acid (TRP@Ag NCs) has been developed for the sensitive and selective fluorometric detection of the anticancer drug gemcitabine. The probe exhibits a blue-emission at 460 nm upon excitation at 320 nm. Various reaction parameters were optimized to enhance the probe’s performance. The addition of gemcitabine results in a decrease in the fluorescence emission, which is attributed to the aggregation of the TRP@Ag NCs. The interaction between the TRP@Ag NCs and gemcitabine involves multiple types of chemical bonds, including non-covalent hydrogen bonding, Van der Waals, and electrostatic forces. The fluorescence ratio (F°/F) exhibits a linear correlation with gemcitabine concentrations ranging from 0.005 to 60 µM, with a low limit of detection (LOD) of 1.7 nM (S/N = 3). The TRP@Ag NCs probe demonstrates high sensitivity, good selectivity, and reliability. The developed probe was successfully applied for the detection of gemcitabine in authentic samples, including pharmaceutical injections, serum, and urine, with acceptable recovery percentages and low relative standard deviation (RSD), indicating the accuracy and reliability of the probe.