One-pot synthesis of silver nanoparticles using folic acid as a reagent for colorimetric and fluorimetric detections of 6-mercaptopurine at nanomolar concentration

•Folic acid-decorated Ag NPs were synthesized and used as a dual probe.•Optical properties of FA-Ag NPs were strongly influenced by the addition of 6-MP.•This method was free from the other chemical species for detection of 6-MP.•This method shows lower detection limit of 13.2 and 2.3 nM for 6-MP.•Selectively detected 6-MP in pharmaceutical and biofluids with reduced sample preparations.

A simple and versatile strategy was developed for dual detection (colorimetric and fluorimetric) of 6-mercaptopurine (6-MP) using folic acid (FA) fabricated silver nanoparticles (Ag NPs) as a probe. The optical properties (surface plasmon resonance (SPR) band and fluorescence) of FA-Ag NPs were strongly influenced by the addition of 6-MP. The abrupt change in absorbance of FA-Ag NPs was observed with increasing concentration of 6-MP, resulting a slight blue-shift in the SPR band and a color change from yellow to colorless, which confirms the oxidation of Ag0 NPs to Ag+ ion. Advantage is taken of the fact that FA is displaced from the surface of the Ag NPs, which progressively enhanced the fluorescence intensity of FA with increasing concentration of 6-MP. The perfect linear variations of absorbance at 399 nm and emission peak at 448 nm with 6-MP concentration was observed in range of 20•1000 and 5•300 nM by UV•vis and fluorescence spectrometric methods, enabling the use of probe as a dual probe for quantification of 6-MP. Moreover, the probe shows excellent anti-disturbance ability when exposed to a series of interfering other organic, inorganic and biomolecules and can be applied to the determination of 6-MP in real samples with the detection limits of 13.2 and 2.3 nM by colorimetric and fluorimetric methods, which suggests that the present method has a great potential of application for assay of 6-MP in pharmaceutical and biological samples.

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