Fluorescence Sensing of Anions Like Adenosine 5'-Triphosphate With pH-Gated Porous Dye-Loaded Cerasomes

The development of gated systems capable of controlled opening of pores on demand represents an attractive way to control chemical functions in many fields of application. Here, we investigate the loading of various reporter dyes into non-porous and porous cerasomes, a hybrid nanoscopic biomimetic material, and how pH-dependent supramolecular adenosine 5'-triphosphate (ATP) binding at the polyaminic gatekeepers anchored at the cerasomes' pore outlets is influencing pH gating. Such organic-inorganic nanovesicles are composed of a siliceous crosslinked lipid bilayer enclosing a liquid-filled void. Preparation of porous cerasomes was achieved by inserting poloxamer block-co-polymers into the membrane during synthesis. To our knowledge, this is the first example of porous cerasomes and their use in gating applications. We successfully encapsulated or loaded reporter molecules into these objects, with the loading preference depending on their charge, hydrophobicity and chemical structure. The addition of molecular gates, responding to pH and/or anions such as ATP, allowed the pores' controlled opening, thereby modulating proton influx, which can be read out via fluorescence response. Considering the corresponding pH sensitivity, dye loaded cerasomes are promising reagents for detecting ATP in relevant concentrations (0.02 to 1000 µM) with distinctly faster fluorescence responses as compared to standard gated mesoporous materials.