Photodynamic therapy (PDT) has shown promising development due to its low toxicity, high selectivity and low side effects. However, the effectiveness of PDT is dependent on the concentration of oxygen and tumor cells have a hypoxia microenvironment that reduces the therapeutic effect of PDT. Therefore, near-infrared absorbing conjugated copolymers with perfluorocarbon side chains, 2,5-bis(2- octyldodecyl)-3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione-co-2,5-thiophene-co-9,9-bis(N-methylperfluorohexylsulfonamidoethyl propionate)- fluorene copolymers, with the ability to generate singlet oxygen under hypoxia conditions were designed and synthesized. The structures of the copolymers were characterized by Fourier transform infrared spectrometer (FTIR) and proton nuclear magnetic resonance spectrum (1HNMR). The singlet oxygen generation ability of the copolymers and corresponding nanoparticles under organic solvents and aqueous conditions was investigated. The results show that the absorption wavelengths of the fluorine-containing conjugated copolymers are greater than 650 nm and they show strong absorption in near-infrared region. The perfluorocarbon (PFC) side chain endows the copolymers with high singlet oxygen generation capability. As the content of fluorine-containing structural units increases, the generation capability of singlet oxygen increases. When the proportion of fluorine-containing structural units is 35%mol (P3-F35%), the copolymer has the singlet oxygen quantum yield of 36.29%. And the singlet oxygen generation capability of the fluorine-containing copolymers is significantly enhanced even under hypoxia conditions. The nanoparticle of fluorine-containing conjugated polymer shows good singlet oxygen generation ability in aqueous suspension. The results of this study indicate that introducing fluorine-containing structure unit into near-infrared absorbing conjugated copolymers is an effective way to enhance the singlet oxygen generation capability of copolymers, which may have broad application prospects in the field of photodynamic therapy.
