Resonance Raman Detection and Estimation in the Aqueous Phase Using Water Dispersible Cyclodextrin: Reduced-Graphene Oxide Sheets

Resonance Raman spectroscopy is a powerful analytical tool for detecting and identifying analytes, but the associated strong fluorescence background severely limits the use of the technique. Here, we show that by attaching β-cyclodextrin (β-CD) cavities to reduced graphene-oxide (rGO) sheets we obtain a water dispersible material (β-CD: rGO) that combines the hydrophobicity associated with rGO with that of the cyclodextrin cavities and provides a versatile platform for resonance Raman detection. Planar aromatic and dye molecules that adsorb on the rGO domains and nonplanar molecules included within the tethered β-CD cavities have their fluorescence effectively quenched. We show that it is possible using the water dispersible β-CD: rGO sheets to record the resonance Raman spectra of adsorbed and included organic chromophores directly in aqueous media without having to extract or deposit on a substrate. This is significant, as it allows us to identify and estimate organic analytes present in water by resonance Raman spectroscopy.