Controlled-synthesis of alumina-graphene oxide nanocomposite coupled with DNA/ sulfide fluorophore for eco-friendly “Turn off/on” H2S nanobiosensor

Hydrogen sulfide (H 2 S) is a toxic environmental pollutant and crucial gas-signaling agent of human physiology. There is an urgent need for developing a sensitive and selective detection approach for H 2 S. Herein, a novel turn off/on response approach using γ-Al 2 O 3 nanorods anchored on the surface graphene oxide (GO) nanosheets and coupled with DNA/sulfide fluorophore (SF) for H 2 S detection at room temperature was developed. The fluorescent fluorophore, DNA/SF, remains quenched on the super quencher γ-Al 2 O 3 –GO hybrid surface. In the existence of H 2 S, DNA/SF fluorophore was detached from γ-Al 2 O 3 –GO hybrid surface because of the strong physical adsorption interaction between H 2 S molecules and γ-Al 2 O 3 –GO surface. The recovered fluorescence intensity gave direct insight about H 2 S concentration in the medium. The developed γ-Al 2 O 3 –GO/DNA/SF nanobiosensor shows high sensitivity with 75 to 2.5 μM linear detection range of H 2 S, and a high binding constant of 9.8 × 10 3  M −1 . The nanobiosensor is very selective toward H 2 S in the presence of various interfering anions and thiols and used for H 2 S detection in real water samples. γ-Al 2 O 3 –GO/DNA/SF nanobiosensor provides a cheap, simple, and highly selective H 2 S detection method at room temperature.