Semiquantification of ATP in live cells using nonspecific desorption of DNA from graphene oxide as the internal reference.

In this aritcle, we have developed an interesting imaging method for intracellular ATP molecules with semiquantitation. While there has been a lot of work in understanding intracellular events, very few can come close to quantitation or semiquantitation in living cells. In this work, we made an effective use of nanomaterials, graphene oxides, both as a quencher and a carrier for intracellular delivery. In addition, this graphene oxide also serves as the carrier for reference probes for fluorescent imaging. An ATP aptamer molecular beacon (AAMB) is adsorbed on graphene oxide (GO) to form a double quenching platform. The AAMB/GO spontaneously enters cells, and then AAMB is released and opened by intracellular ATP. The resulting fluorescence recovery is used to perform ATP live-cell imaging with greatly improved background and signaling. Moreover, a control ssDNA, which is released nonspecifically from GO by nontarget cellular proteins, can serve as an internal reference for ATP semiquantification inside living cells using the intensity ratio of the AAMB and control. This approach can serve as a way for intracellular delivery and quantitative analysis.