Macrotheranostic Probe with Disease‐Activated Near‐Infrared Fluorescence,Photoacoustic, and Photothermal Signals for Imaging‐Guided Therapy

Theranostics provides opportunities for precision cancer therapy. However, theranostic probes that simultaneously turn on their diagnostic signal and pharmacological action only in respond to a targeted biomarker have been less exploited. We herein report the synthesis of a macrotheranostic probe that specifically activates its near‐infrared fluorescence (NIRF), photoacoustic (PA), and photothermal signals in the presence of a cancer‐overexpressed enzyme for imaging‐guided cancer therapy. Superior to the small‐molecule counterpart probe, the macrotheranostic probe has ideal biodistribution and renal clearance, permitting passive targeting of tumors, in situ activation of multimodal signals, and effective photothermal ablation. Our study thus provides a macromolecular approach towards activatable multimodal phototheranostics.     

Organic Nanocrystals with Bright Red Persistent Room‐Temperature Phosphorescence for Biological Applications

Persistent room‐temperature phosphorescence (RTP) in pure organic materials has attracted great attention because of their unique optical properties. The design of organic materials with bright red persistent RTP remains challenging. Herein, we report a new design strategy for realizing high brightness and long lifetime of red‐emissive RTP molecules, which is based on introducing an alkoxy spacer between the hybrid units in the molecule. The spacer offers easy Br−H bond formation during crystallization, which also facilitates intermolecular electron coupling to favor persistent RTP. As the majority of RTP compounds have to be confined in a rigid environment to quench nonradiative relaxation pathways for bright phosphorescence emission, nanocrystallization is used to not only rigidify the molecules but also offer the desirable size and water‐dispersity for biomedical applications.     

A Highly Photostable Near‐Infrared Labeling Agent Based on a Phospha‐rhodamine for Long‐Term and Deep Imaging

Various fluorescence microscopy techniques require bright NIR‐emitting fluorophores with high chemical and photostability. Now, the significant performance improvement of phosphorus‐substituted rhodamine dyes (PORs) upon substitution at the 9‐position with a 2,6‐dimethoxyphenyl group is reported. The thus obtained dye PREX 710 was used to stain mitochondria in living cells, which allowed long‐term and three‐color imaging in the vis‐NIR range. Moreover, the high fluorescence longevity of PREX 710 allows tracking a dye‐labeled biomolecule by single‐molecule microscopy under physiological conditions. Deep imaging of blood vessels in mice brain has also been achieved using the bright NIR‐emitting PREX 710‐dextran conjugate.