Stepwise phosphorescence energy transfer for NIR cell imaging based on macrocycle disaggregated amphiphile

Abstract

A multicolor phosphorescence supramolecular system was constructed based on the complexation of amphiphile (G) and cucurbit[8]uril (CB[8]). The guest G which was composed of hydrophobic coumarin and hydrophilic phosphor 6-bromoisoquinoline can aggregate in water and form large nanosheets accompanying bright fluorescence at 390 nm. After encapsulated by CB[8], the aggregation was prohibited and formed nanosheets with smaller size and the fluorescence peak at 390 nm decreased, meanwhile a phosphorescence peak at 550 nm appeared. Upon the adding of lower-rim dodecyl-modified sulfonatocalix[4]arene (SC4AD), the aggregation was disrupted and particles were formed which were a few 10s of nanometers in size. Subsequently, a stepwise high efficient phosphorescence energy transfer system with a variety of colors was constructed with rhodamine B (RhB) and Sulfo-Cyanine 5 (cy5)/Si-rhodamine (SiR) as acceptors. Finally, the multicolor phosphorescent supramolecular assembly was used to near-infrared cell imaging.