Co-delivery of NIR-II semiconducting polymer and pH-sensitive doxorubicin-conjugated prodrug for photothermal/chemotherapy.

Semiconducting polymer (SP) is a promising photothermal agent in the antitumor application, but the co-delivery of the second near-infrared window (NIR-II)-based SPs with chemotherapeutic drug (e.g., doxorubicin (DOX)) remains a challenge. Here, SPs were firstly improved via backbone and alkyl side-chain engineering, and afterward, SPs and pH-sensitive prodrug copolymer self-assembled into a nanoparticle for a photoacoustic (PA)-imaging guided combination of photothermal therapy and chemotherapy. SP-encapsulated nanoparticles exhibited a high photothermal conversion efficiency of 45% at a relatively low power level of NIR irradiation (0.3 W/cm2 for 5 min). DOX was rapidly released in response to the acidic lysosomal environment. PA and fluorescence imaging confirmed that the photothermal therapy effectively drove DOX penetration inside tumor tissue, and it resulted in the killing of the surviving tumor cells from hyperthermia. The synergistic effect of SP-based photothermal therapy and DOX-induced chemotherapy was verified in vivo. Overall, the co-delivery of the SP and DOX using pH-sensitive nanoparticles represents a feasible strategy for photothermal therapy with potentially synergistic drug effects. STATEMENT OF SIGNIFICANCE: Recent years have yielded great progress in semiconducting polymers (SPs)-based photothermal therapy for anticancer treatment. However, studies about molecular weight and side-chain of SPs on photothermal conversion efficiency are limited, and investigation of controlled codelivery with chemotherapeutic drug is lacking. Here, we improved the SPs performance via backbone and side-chain engineering, and afterward offered a pH-sensitive DOX-conjugated amphiphilic copolymer to encapsulate SPs. SP-encapsulated nanoparticles exhibited high photothermal conversion efficiency at a clinically feasible power level of NIR irradiation. NIR irradiation-generated hyperthermia not only killed tumor cells but also promoted DOX penetration inside the tumor tissue to ablate the tumor cells that survived hyperthermia. The synergistic effect of SP-based photothermal therapy and DOX-induced chemotherapy was verified in vivo.

Unraveling the Unconventional Order of a High-Mobility Indacenodithiophene-Benzothiadiazole Copolymer.

A new class of donor-acceptor (D-A) copolymers found to produce high charge carrier mobilities competitive with amorphous silicon (>1 cm2 V-1 s-1) exhibit the puzzling microstructure of substantial local order, however lacking long-range order and crystallinity previously deemed necessary for achieving high mobility. Here, we demonstrate the application of low-dose transmission electron microscopy to image and quantify the nanoscale and mesoscale organization of an archetypal D-A copolymer across areas comparable to electronic devices (≈9 µm2). The local structure is spatially resolved by mapping the backbone (001) spacing reflection, revealing nanocrystallites of aligned polymer chains throughout nearly the entire film. Analysis of the nanoscale structure of its ordered domains suggests significant short- and medium-range order and preferential grain boundary orientations. Moreover, we provide insights into the rich, interconnected mesoscale organization of this new family of D-A copolymers by analysis of the local orientational spatial autocorrelations.