Green synthesis of methyl gallate conjugated silver nanoparticles: a colorimetric probe for gentamicinElectronic supplementary information (ESI) available. See DOI: 10.1039/c8nj04565h

Gentamicin is a broad spectrum antibiotic employed for the cure of infections caused by both Gram-positive and Gram-negative bacteria. It is eliminated through urine in the unmetabolized and microbiologically active form, leading to the emergence of gentamicin-resistant bacteriocoenosis. Green synthesis of methyl gallate conjugated silver nanoparticles (MG-AgNPs) is reported in this study. The synthesized MG-AgNPs were found to be stable at high temperature, in the pH range 4 to 8, and with up to 100 mM NaCl concentration in the solution. Further, the synthesized MG-AgNPs were employed as a selective and sensitive probe for the detection of gentamicin. The proposed colorimetric aggregation sensor significantly detected gentamicin over a wide range of concentrations in the presence of other interfering drugs and metal ions. UV-visible spectroscopy, FTIR, and atomic force microscopy were employed to confirm the sensing phenomenon. The binding ratio of MG-AgNPs with gentamicin was found to be equimolar. The limit of detection and quantification were found to be 0.29 μM and 1 μM, respectively, in the concentration range of 1-100 μM. The proposed sensor significantly detects gentamicin in environmental waters, human blood plasma, serum, and urine. A highly efficient colorimetric sensor for gentamicin is proposed based on methyl gallate conjugated silver nanoparticles.