Ultrasensitive, highly selective and naked eye colorimetric recognition of D-penicillamine in aqueous media by CTAB capped AgNPs: applications to pharmaceutical and biomedical analysis

Herein, we are going to report a straightforward, highly selective and ultra sensitive naked eye colorimetric probe for the detection of D-penicillamine (D-PA) in aqueous solution using cetyltrimethyl ammonium bromide (CTAB) capped colloidal silver nanoparticles (AgNPs) based on induced aggregation. The synthesized CTAB-AgNPs and their interaction with D-PA were characterized by different analytical techniques such as UV-Vis absorption spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS) measurements and zeta potential measurements. The color of the CTAB-AgNPs solution changed from yellowish brown to colorless within short period of time after the successive addition of D-PA, resulting in a blue shift with quenching in the absorption spectra. Under the optimal conditions, a calibration plot of (A(0)-A) against concentration of D-PA was linear in the range of 0.1-0.6 mu g mL(-1) with a correlation coefficient of 0.9901. The concentration of D-PA was quantitatively determined using an UV-Vis spectrophotometer with a limit of detection (LOD) of 0.056 mu g mL(-1) (56 ng mL(-1)). In addition, the method shows an excellent selectivity and sensitivity towards D-PA over the other interfering biomolecules and cations tested. The accuracy and reliability of the method were further ascertained from the detection of D-PA from pharmaceutical and biomedical samples via a standard addition method, with percentage recoveries in the range of 98.32-102.94%. A plausible reason for the observed color changes is also discussed. The proposed method is simple, rapid, specific and highly selective and sensitive with good precision.