Mitochondria-targeting single-layered graphene quantum dots with dual recognition sites for ATP imaging in living cells.

As a molecular unit of intracellular energy transfer, adenosine triphosphate (ATP) is significant for maintaining the energy balance in living cells and thus monitoring cellular ATP is important to assess cellular physiological functions. However, effective monitoring of cellular ATP still faces challenges owing to the similarity of ATP to other nucleoside polyphosphates. Herein, yellow emissive single-layered graphene quantum dots (s-GQDs) with dual recognition sites including π-conjugated single sheets and positively charged sites were developed. The s-GQDs exhibit a good mitochondria targeting ability and respond only to purine nucleotides and show good selectivity in discriminating tri-, di- and monophosphate nucleotides. The good selectivity should be attributed to the concurrent effect of π-π stacking and electrostatic interactions between filmy layered positive s-GQDs and negative purine nucleotides. Owing to the mitochondria targeting ability and dual recognition sites of the s-GQDs, the mitochondrial ATP fluctuation resulting from the activation and suppression of ATP in living cells has been successfully monitored.