Tumor Imaging Based on Photon Upconversion of Pt(II) Porphyrin Rhodamine Co-modified NIR Excitable Cellulose Enhanced by Aggregation.

We report a bioinspired upconversion (UC) system using a cellulose template, in which an aggregated platinum(II)-tetraphenylporphyrin (PtTPP) sensitizer is able to excite Rhodamine B as an emitter, enabling near-infrared (NIR)-to-orange wavelength conversions. The comodified cellulose was observed to undergo J aggregation of PtTPP in DMSO solution, as indicated by broad, weak absorption bands in the NIR region of the absorption spectrum. Excitation of these NIR J aggregation peaks of PtTPP led to efficient UC emission in the orange wavelength region. These materials were shown to exhibit UC properties in biological settings both in vitro and in vivo, demonstrating utility of UC for tumor imaging.