Colorimetric Sensors for Recognition of Chiral Drugs Using Gold Nanoparticles

Using L-cysteine capped gold nanoparticles (L-Cys-AuNPs) as a colorimetric sensor, an easy, low-cost, and highly efficient strategy for the optical chiral identification of ketoprofen enantiomers was developed. R-ketoprofen tends to rapidly adsorb onto L-Cys-AuNPs, resulting in a color change of the solution from red to purple; however, no significant change was observed upon the addition of S-ketoprofen. The potential of L-cysteine capped with AuNPs (L-Cys-AuNPs) as chiral selectors for the recognition of ketoprofen enantiomers has been investigated using UV–Vis, FESEM, FT-IR, SERS, and zeta potential. The recognition process is easily identified by the naked eye or by using a UV–Vis spectrometer. Sensors L-Cys-AuNPs revealed a good linear response to ketoprofen enantiomers in the concentration range of 8.33–33.33 μM with a relative standard deviation of 3.08%. And detection limit of 2.35 μM. The proposed method was applied to determine the ketoprofen racemic mixture in water samples and commercial tablets. This method represents easy, inexpensive, simple, and very effective methods for the recognition of ketoprofen enantiomers.