Colorimetric and SERS detection of H2S by D (±) galactose functionalized truncated hexagonal bipyramidal silver nanoresonators

[Display omitted] •This communication involves a green synthesis of silver nanoparticles(AgNPs) using a monosacchharide viz., galactose.•The comparative preparatory studies have also been performed with few monoscasccharides, a discccharide and a polysaccharide.•The truncated hexagonal bipyramidal geometries were seen in the HR-TEM images of as prepared AgNPs.•The as prepared AgNPs exhibited excellent colorimetric response (greenish yellow to brown) upon their interaction with H2S.•These AgNPs exhibited very nice SERS characteristics also against H2S. We report hereby, a simple and easy to perform experimental protocol for highly selective and real time dual mode (Colorimetric and SERS) detection of hydrogen sulfide (H2S) in aqueous medium through galactose activated silver nanoresonators. The truncated hexagonal bipyramids were clearly seen in TEM images of as prepared silver nanoparticles. The interaction of H2S with these AgNPs induced their etching followed by agglomeration and led optical (greenish yellow to brown) as well as SERS changes. The optical changes were further exploited to determine the H2S from its two spiked samples of human saliva and blood serum each with their percent recovery rates of 91, 82 and 67, 72 respectively. These determinations were totally free from any visual interference from any biothiols like cysteine, homocysteine and glutathione. The optimized silver nanosensor exhibited an excellent linear response in the concentration range of 50–130 nM along with its limit of detection (LOD) as 2.83 nM. Moreover, consecutive additions of different aliquots of H2S to a fixed volume of these silver colloids exhibited stepwise decrease in intensity of their absorption bands in the Raman silent (10–500 cm−1) and Raman finger print regions (500–1800 cm−1) upon their excitation at 532 nm. Our findings are well supported by spectroscopic (FTIR, UV–Vis and Raman) and microscopic (SEM, TEM, DLS and zeta potential).