Graphene oxide based fluorescence sensor for cucurbit[7]uril

Abstract

Rhodamine B (RhB) anchored reduced graphene oxide (RhBGO) offers a very sensitive and selective sensing potential for cucurbit[7]uril (CB[7]). Apart from CB[7], RhBGO does not respond to other cucurbituril homologues or to β-cyclodextrin (β-CD), presumably due to their inability to remove RhB from RhBGO. Besides a good selectivity, RhBGO also shows a good sensitivity towards CB[7] to a maximum concentration of 10⁻⁷ M in phosphate buffer. CB[7] induces the detachment and inclusion of RhB from RhBGO, and the inclusion phenomena has been confirmed by the addition of a competitive guest such as adamantylamine, which reduces the intensity of the fluorescence due to the exclusion of RhB from the cavity of CB[7]. Furthermore, RhBGO helps to visualize CB[7] under UV light. Following this detection method, we have utilized RhBGO for the detection of CB[7] in spiked urine samples and on TLC plates. This new graphene based material could be a very useful tool for the detection of CB[7] in buffer with good selectivity and sensitivity.