Colorimetric detection of Hg(II) by γ-aminobutyric acid-silver nanoparticles in water and the assessment of antibacterial activities

Abstract

In this work, we report the synthesis of silver nanoparticles (AgNPs) via a wet-chemical reduction procedure using citrate (Cit) and γ-aminobutyric acid (GABA) as stabilizers. The formation of GABA-Cit@AgNPs was confirmed by UV-vis spectroscopy with a surface plasmon resonance band at 393 nm clearly confirming the formation of silver nanoparticles. AgNPs were characterized using UV-vis spectroscopy, attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), dynamic light scattering (DLS), and zeta potential. The as-prepared AgNPs can be used for the detection of hazardous mercury ions (Hg²⁺) in water by colorimetric method with a limit of detection (LOD) and limit of quantitation (LOQ) of 2.37 μM and 3.99 μM, respectively. The linear working range for Hg²⁺ detection is 5-35 μM and the sensor probe was applied to investigate Hg²⁺ in real drinking water samples with satisfied results. Rapid response to Hg²⁺ is also observed when the nanoparticles are composited within hydrogels. Moreover, GABA-Cit@AgNPs shows antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The fast and sensitive response of the proposed Hg²⁺ sensor, together with its antibacterial activities, makes GABA-Cit@AgNPs potentially applicable for the development of cheap, portable, colorimetric sensors in fieldwork.

Keywords: Antibacterial; Mercury sensing; Silver nanoparticles; γ-aminobutyric acid.