Organic Afterglow Emulsions Exhibiting 2.4 s Phosphorescence Lifetimes and Specific Protein Binding Property

Abstract Aqueous afterglow dispersions display promising biomedical applications due to their long‐lived excited states, whereas it is a common problem in the research field that processing and transferring solid‐state afterglow materials into aqueous medium can cause significant drop and even complete loss of their afterglow properties. Here, aqueous afterglow dispersions are fabricated from liquid precursors by dopant–matrix strategy and emulsion polymerization, which avoids the processing procedures on solid‐state materials and achieves 2.4 s long phosphorescence lifetimes in aqueous medium. Luminescent difluoroboron β‐diketonate dopants are first designed with small rate constant of phosphorescence decay and then dissolved in monomers. After emulsion polymerization, the as‐formed polymer latex particles not only assist dopants’ intersystem crossing but also provide a glassy microenvironment to largely suppress nonradiative decay of dopants’ triplets, leading to in situ formation of aqueous afterglow dispersions. This provides a robust method for constructing afterglow emulsions with long‐term colloidal stability, relatively high solid contents, tunable sizes, and diverse compositions. Through emulsion copolymerization, afterglow emulsions decorated with specific ligands are obtained to exhibit specific protein binding properties. Such decorated afterglow emulsions address the issue that afterglow materials lack biorecognition property and can pave the way for their applications in immunoassay and immunoimaging.