Uniform pi-Conjugated-Co-Oligomer-Based Nanofibers of Controlled Length with Near-Infrared Emission, Photodynamic and Photothermal Activities

pi-Conjugated-polymer-based nanofibers (CPNFs) have attracted considerable interest in the community of nanomedicine owing to their high-aspect-ratio architecture and inherent photo-imaging, photothermal, photodynamic, and photoacoustic properties. However, the preparation of uniform CPNFs of controlled length and composition with near-infrared emission (NIR), photothermal and photodynamic activity remains in its infancy. A novel block copolymer consisting of a donor-acceptor-donor (D-A-D) pi-conjugated co-oligomer with a diketopyrrolopyrrole (DPP) unit as electron-deficient acceptor flanked by oligo(p- phenylene ethynylene) (OPE) as an electron-rich donor and a poly(2-vinylpyridine) (P2VP) block (OPE4-DPP-OPE4-b-P2VP(44), the subscripts describe the extra and average number of repeat units for pi-conjugated OPE segment and P2VP block, respectively) is designed and synthesized. By using the self-seeding approach of living crystallization-drive self-assembly (CDSA), uniform CPNFs containing a D-A-D OPE4-DPP-OPE4 core and a P2VP corona with tunable length from 31 to 611 nm are generated. The resulting CPNFs exhibit NIR emission with a peak at 837 nm. The CPNFs also can serve as a photosensitizer to efficiently produce single oxygen and show a photothermal effect upon 660 nm irradiation. To the author's best knowledge, it is the first report on the generation of uniform CPNFs of controlled length with NIR emission, and photodynamic and photothermal activities by living CDSA.