No abstract

Tumor hypoxia seriously impairs the therapeutic outcomes of type II photodynamic therapy (PDT), which is highly dependent upon tissue oxygen concentration. Herein, a facile strategy of acceptor planarization and donor rotation is proposed to design type I photosensitizers (PSs) and photothermal reagents. Acceptor planarization can not only enforce intramolecular charge transfer to redshift NIR absorption but also transfer the type of PSs from type II to type I photochemical pathways. Donor rotation optimizes photothermal conversion efficiency (PCE). Accordingly, three 3,6-divinylsubstituted diketopyrrolopyrrole (DPP) derivatives, 2TPAVDPP, TPATPEVDPP, and 2TPEVDPP, with different number of rotors were prepared. Experimental results showed that three compounds were excellent type I PSs, and the corresponding 2TPEVDPP nanoparticles (NPs) with the most rotors possessed the highest PCE. The photophysical properties of 2TPEVDPP NPs are particularly suitable for in vivo NIR fluorescence imaging-guided synergistic PDT/PTT therapy. The proposed strategy is helpful for exploiting type I phototherapeutic reagents with high efficacy for synergistic PDT and PTT.

The complexation of poly(styrene-co-vinylphenol) (STVPh) and poly(styrene-co-vinylpyridine) (STVPy) in nonaqueous solution was investigated with emphasis on the effect of the hydroxyl and pyridyl contents in the component polymers. Viscometry, nonradiative energy transfer fluorospectroscopy, and dynamic laser light scattering have led to the same conclusion, i.e., STVPh and STVPy blend can form an interpolymer complex due to hydrogen bonding in tetrahydrofuran, butanone, and chloroform, provided the contents of the hydroxyl and pyridyl reach certain respective levels. The size distribution of the complex aggregates is relatively narrow with a peak size 1 order of magnitude larger than those of the component polymer coils. The minimum content of the interaction groups required for complexation strongly depends on the solvent used. Chloroform and butanone are almost inert for hydrogen bonding between the polymers, tetrahydrofuran has a substantial influence on complexation, and addition of N,N-dimethylformamide into the dispersion of complex aggregates in THF even causes decomplexation.