Surfactant-Stripped Micelles with Aggregation-Induced Enhanced Emission for Bimodal Gut Imaging In Vivo and Microbiota Tagging Ex Vivo

Aggregation-induced emission luminogens (AIEgens) hold promise for biomedical imaging and new approaches facilitating their aggregation state are desirable for fluorescence enhancement. Herein, a series of surfactant-stripped AIEgen micelles (SSAMs) with improved fluorescence are developed by a low-temperature surfactant-stripping method to encapsulate AIEgens in temperature-sensitive Pluronic block copolymer. After stripping excessive surfactant, SSAMs exhibit altered optical properties and significantly higher fluorescence quantum yield. Using this method, a library of highly concentrated fluorescent nanoparticles are generated with tunable absorption and emission wavelengths, permitting imaging of deep tissues at different wavelengths. SSAMs remain physiologically stable and can pass safely through gastrointestinal tract (GI) without degradation in the harsh conditions, allowing for fluorescence and photoacoustic imaging of intestine with high resolution. d-amino acids (DAA), a natural metabolite for bacteria, can be chemically conjugated on the surface of SSAMs, enabling non-invasive monitoring of the microbial behavior of ex vivo fluorescently labeled gut microbiota in the GI tract.

Automated summary

Surfactant-stripped AIEgen micelles (SSAMs) with improved fluorescence properties and high fluorescence quantum yield were developed using a low-temperature surfactant-stripping method. These SSAMs can generate highly concentrated fluorescent nanoparticles for deep tissue imaging at different wavelengths, while remaining stable in the gastrointestinal tract for high-resolution fluorescence and photoacoustic imaging of the intestine. Additionally, SSAMs can be chemically conjugated with d-amino acids (DAA) for non-invasive monitoring of microbial behavior in ex vivo fluorescently labeled gut microbiota in the GI tract.