Miniemulsion polymerization-formulated poly(fluorene-alt-6-(2-ethylhexyl)-[1,2,5]thiadiazole[3,4-f]benzotriazole) for cancer cell imaging

Rational Design of NIR-II Emitting Conjugated Polymer Derived Nanoparticles for Image-Guided Cancer Interventions

Due to the reduced absorption, light scattering, and tissue autofluorescence in the NIR-II (1000-1700 nm) region, significant efforts are underway to explore diverse material platforms for in vivo fluorescence imaging, particularly for cancer diagnostics and image-guided interventions. Of the reported imaging agents, nanoparticles derived from conjugated polymers (CPNs) offer unique advantages to alternative materials including biocompatibility, remarkable absorption cross-sections, exceptional photostability, and tunable emission behavior independent of cell labeling functionalities. Herein, the current state of NIR-II emitting CPNs are summarized and structure-function-property relationships are highlighted that can be used to elevate the performance of next-generation CPNs. Methods for particle processing and incorporating cancer targeting modalities are discussed, as well as detailed characterization methods to improve interlaboratory comparisons of novel materials. Contemporary methods to specifically apply CPNs for cancer diagnostics and therapies are then highlighted. This review not only summarizes the current state of the field, but offers future directions and provides clarity to the advantages of CPNs over other classes of imaging agents.

NIR-II Excitable Water-Dispersible Two-Dimensional Conjugated Polymer Nanoplates for In Vivo Two-Photon Luminescence Bioimaging

While two-dimensional conjugated polymers (2DCPs) have shown great promise in two-photon luminescence (TPL) bioimaging, 2DCP-based TPL imaging agents that can be excited in the second near-infrared window (NIR-II) have rarely been reported so far. Herein, we report two 2DCPs including 2DCP1 and 2DCP2, with octupolar olefin-linked structures for NIR-II-excited bioimaging. The 2DCPs are customized with the fully conjugated donor-acceptor (D-A) linkage and aggregation-induced emission (AIE) active building blocks, leading to good two-photon absorption into the NIR-II window with a 2PACS of ∼64.0 GM per choromophore for both 2DCPs. Moreover, 2DCP1 powders can be exfoliated into water-dispersible nanoplates with a Pluronic F-127 surfactant-assisted temperature-swing method, accompanied by both a drastic reduction of 2PACS throughout the range of 780-1080 nm and a sharp increase of photoluminescence quantum yield to 33.3%. The 2DCP1 nanoplates are subsequently proven to be capable of assisting in visualizing mouse brain vasculatures with a penetration depth of 421 μm and good contrast in vivo, albeit that only 19% of previous 2PACS at 1040 nm is preserved. This work not only provides important insights on how to construct NIR-II excitable 2DCPs for TPL bioimaging but also how to investigate the exfoliation-photophysical property correlation of 2DCPs, which should aid in future research on developing highly efficient TPL bioimaging agents.