Tailored graphene/silica functional composite as signaling and adsorbent material: A sequential excimer probe with a fluoro-switching response with zinc and adenosine triphosphate

Graphene as a sensory platform with luminescent tags faces agglomeration and fluorescence quenching chal-lenges. Therefore, composite materials derived from graphene and mesoporous silica are studied to address the issues with their cooperative actions. However, such materials are rare and are never explored for simultaneous sensing and adsorption studies. Therefore, in this work, a modified approach was made to produce better quality graphene oxide, which was subsequently used for preparing reduced graphene oxide/silica composite (rGOm-SiO2) and further functionalized with quinoline-based ligand to create a functional composite (rGOmSiO2@BI-QINOL) for specificity. This material shows very selective TURN-ON fluorescence sensing of zinc-ion among various cations and anions through a coordination-driven excimer formation (rGOmSiO2@BIQINOL@Zn). Sub-sequently, the above Zn-adduct shows a TURN-OFF fluorescence emission with ATP (adenosine triphosphate) via coordination-driven excimer breakdown (rGOmSiO2@BIQINOL@Zn@ATP). A sequential probing of Zn2+ and ATP with a very sensitive limit of detection (27 nM & 157 nM, respectively) was demonstrated. The adsorption studies show high adsorption capacities for Zn (595 mg g-1) and ATP (445 mg g-1) with the material's recy-clability. Also, the materials were used precisely for real sample quantification of Zinc & ATP. The simultaneous detection and adsorption of Zn and ATP with material recyclability is advantageous compared to literature reports.