Cypate-sensitized upconversion nanoprobes for intracellular and in-vivo ATP ratiometric detection.

Cypate-sensitized lanthanide upconversion nanoprobes with NIR dual-excitation have been developed for ratiometric detection of ATP in living cells and zebrafish larvae. The involved interfacial interactions and underlying energy transfer pathway were deeply explored. [Display omitted] • ATP-responsive dual NIR-excitation ratiometric nanoprobes were constructed. • The interfacial interactions and underlying photophysics in the nanoprobes were explored. • The nanoprobes were applied for the quantification of the ATP level in living cells. • The nanoprobes provided accurate monitoring of the in-vivo ATP fluctuation. As energy currency of life, adenosine triphosphate (ATP) is highly dynamic in living organisms. It is crucial yet challenging to probe intracellular or in-vivo ATP precisely without destruction of the living biological systems. Herein, we have designed novel ATP-responsive ratiometric nanoprobes by employing upconversion nanoparticles (UCNPs) with cypate as antennas. Nuclear magnetic resonance spectroscopy was used to analyze the interfacial interactions among lanthanide nanocrystal, cypate and adenosine phosphates, disclosing the origin of detection specificity. ATP induced interruption of energy transfer pathway in cypate-sensitized UCNPs was further investigated by femtosecond transient absorption and time-resolved photoluminescence spectroscopy. The nanoprobes with dual near-infrared (NIR)-excited ratiometric UCL were successfully applied for quantification of ATP level in living cells under vegetatively growing, starving, and glycolysis-inhibiting states, respectively. Furthermore, the increase of available energy by feeding for zebrafish larvae was confirmed through monitoring the in-vivo ATP variation with the nanoprobes. Such nanoprobes showed great potential in ATP-associated biological research and clinical applications. These findings may gain deep insights into the surface science and photophysics in dye-lanthanide nanocomposites, and open new avenues for the design and bioapplications of lanthanide nanoprobes. [ABSTRACT FROM AUTHOR]