Lemon-based core–shell Au@Pd nanoparticles as green nanoprobe: Towards fast and visual detection of trifluoperazine

Monitoring of trifluoperazine (TFP) levels in biofluids is medically important. The present study introduces a cost-effective colorimetric sensor based on the core–shell gold–palladium nanoparticles (Au@Pd NPs) as the nanoprobe for the naked-eye and rapid detection of trace amounts of TFP. The green core–shell Au@Pd NPs has been successfully synthesized in a facile and environmentally friendly procedure. HAuCl4 and H2PdCl4 were used as the precursors, and citrus limon (lemon) was used as both reducing and stabilizing agents. Adding TFP with different concentrations to the core–shell Au@Pd NPs in the presence of phosphate buffer (PB) presented a peak at 465 nm with the orange color tonalities, which differed from the Au NPs (at 555 nm with purple color) and Pd NPs (415 nm with brown color), individually. The resulting absorption spectra change was linearly proportional to the concentration increasing of TFP from 6 µM to 65 µM with a detection limit (LOD) of 60 nM. The practical applicability of the proposed TFP sensor was evaluated in real human serum, saliva, urine and pharmaceutical samples. Applicability of the sensor for TFP assay in biofluids and pharmaceutical sample was confirmed by HPLC analysis as the reference method and the results were evaluated by Lunn's test and t-test statistical analysis. The resulting easy-to-use and cost-effective smartphone-based sensing is promising as a technical support for finding utility for rapid and sensitive therapeutic drug monitoring (TDM) of TFP in clinical analysis.