Abstract
It is highly desired that synthesis of photothermal agents with near-infrared (NIR) absorption, excellent photostability, and high photothermal conversion efficiency are essential for potential applications. In this work, three (D-A) conjugated polymers (PBABDF-BDTT, PBABDF-BT, and PBABDF-TVT) based on aza-heterocycle, bis(2-oxo-7-azaindolin-3-ylidene)benzodifurandione (BABDF) as the strong acceptor, and benzodithiophene-thiophene (BDTT), bithiophene (BT), and thiophene-vinylene-thiophene (TVT) as the donors, were designed and synthesized. The conjugated polymers showed significant absorption in the NIR region and a maximum absorption peak at 808 nm by adjusting the donor and acceptor units. Their photothermal properties were also investigated by using poly(ethylene glycol)-block-poly(hexyl ethylene phosphate) (mPEG-b-PHEP) to stabilize the conjugated polymers. Photoexcited conjugated polymer (PBABDF-TVT) nanoparticles underwent non-radiative decay when subjected to single-wavelength NIR light irradiation, leading to an excellent photothermal conversion efficiency of 40.7%. This work indicated the aza-heterocycle BABDF can be a useful building block for constructing D-A conjugated polymer with high conversion efficiency.
Highlights
Near-infrared (NIR) light has been widely used in sensing, imaging, and biotherapy fields (Qian et al, 2013; Yang et al, 2013; He et al, 2015; Antaris et al, 2016; Song et al, 2016; Zhang et al, 2016), owing to its superior advantages in remote sensing operations, microinvasion, and biological window
The D-A conjugated polymer (PBIBDF-BT) had the absorption extend to the NIR region and exhibited excellent photothermal conversion efficiency (34.7%) (Yang et al, 2017)
The structures were characterized by nuclear magnetic resonance (NMR) (Figures S5–S7)
Summary
Near-infrared (NIR) light has been widely used in sensing, imaging, and biotherapy fields (Qian et al, 2013; Yang et al, 2013; He et al, 2015; Antaris et al, 2016; Song et al, 2016; Zhang et al, 2016), owing to its superior advantages in remote sensing operations, microinvasion, and biological window. The D-A conjugated polymer (PBIBDF-BT) had the absorption extend to the NIR region and exhibited excellent photothermal conversion efficiency (34.7%) (Yang et al, 2017). The polymer based on TVT as donor and BABDF as acceptor exhibited an excellent extinction coefficient of 55 cm−1·mg−1·mL and a high photothermal conversion efficiency of 40.7%.
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