Ternary Interactions and Energy Transfer between Fluorescein Isothiocyanate, Adenosine Triphosphate, and Graphene Oxide Nanocarriers

The interactions of fluorescent probes and biomolecules with nanocarriers are of key importance to the emerging targeted drug delivery systems. Graphene oxide nanosheets (GONs) as the nanocarriers offer biocompatibility and robust drug binding capacity. The interactions of GONs with fluorophores lead to strong fluorescence quenching, which may interfere with fluorescence bioimaging and biodetection. Herein, we report on the interactions and energy transfers in a model ternary system: GONs–FITC–ATP, where FITC is a model fluorophore (fluorescein isothiocyanate) and ATP is a common biomolecule (adenosine-5′-triphosphate). We have found that FITC fluorescence is considerably quenched by ATP (the quenching constant KSV = 113 ± 22 M–1). The temperature coefficient of KSV is positive (αT = 4.15 M–1deg–1). The detailed analysis of a model for internal self-quenching of FITC indicates that the temperature dependence of the net quenching efficiency η for the FITC–ATP pair is dominated by FITC internal self-quenchi...