Near‐Infrared Fluorescence/Photoacoustic Agent with an Intensifying Optical Performance for Imaging‐Guided Effective Photothermal Therapy

Abstract

Near-infrared fluorescent agents generally exhibit typical push-pull electron characteristics, and their optical behaviors are closely related to their molecular structures. Benzobisthiadiazole moiety as a classic electron acceptor has been typically used to design the Donor-Acceptor-Donor (D-AD) type of fluorescent/photoacoustic agents with emission in the second near-infrared window. In this work, two strategies are examined to intensify their absorption/fluorescence and fluorescence/photoacoustic imaging performance: 1) the conjugated bridges are amplified by installing two electron-rich thiophenes and one styrene on two sides of the benzobisthiadiazole core and 2) the N,N-dimethylamino group is employed to replace the traditional diphenylamine to strengthen the electron donor. This agent shows the maximum absorption and fluorescence emission at 942 and 1302 nm, respectively. Its superior in vitro and vivo data confirms that the nanoparticles of this compound complexed with 1,2-distearoyl-sn-glycero-3phosphoethanolamine-N-[methoxy(polyethyleneglycol)] (DSPE-PEG) can not only perform real-time and high-contrast noninvasive near-infrared fluorescence/photoacoustic imaging of tumors (980 nm laser irradiation) but also effectively ablate the tumor cells by photothermal therapy implementing the dual-modality imaging method. In particular, its longer wavelength absorption and emission successfully improves the fluorescence/ photoacoustic imaging performance. These observations highlight its potential to be used as a promising therapeutic platform for cancer.

Near-Infrared Thienoisoindigos with Aggregation-Induced Emission: Molecular Design, Optical Performance, and Bioimaging Application

“…In comparison to the TPA, the N , N -dimethyl group has a stronger electron-donating capability . To further extend the NIR emission of the AIE materials, we attempted to modify the molecular structure.…”

“…In comparison to the TPA, the N,N-dimethyl group has a stronger electron-donating capability. 60 To further extend the NIR emission of the AIE materials, we attempted to modify the molecular structure. On the one hand, the N,N-dimethyl group was employed to enhance the electron-donating ability.…”

Flexible Designing Strategy to Construct Activatable NIR-II Fluorescent Probes with Emission Maxima beyond 1200 nm

“…(3) Commonly used photoinduced electron transfer (PeT) and Förster resonance energy transfer (FRET) mechanism face challenges in the NIR-II region . (4) There was no organic fluorophore reported with >1200 nm emission maximum until last several months. , Therefore, it is not only highly demanded but also very challenging to develop a strategy that can flexibly modulate the emission wavelength and then construct long-emission activatable probes based on a stable and water-soluble fluorophore.…”

The Chemistry of Organic Contrast Agents in the NIR‐II Window

“…Hongsg roup developed BBTD-1302 (7k)b y employing 3,4-ethylenedioxythiophene-containing bithiophene and styrene as the conjugating bridge,a nd N,Ndimethylamino groups as electron donors. [82] Theoretical calculations revealed intramolecular charge transfer (ICT) from the N,N-dimethylamino groups to the BBTD core and ab and gap of 0.88 eV,w hich afforded longer-wavelength maximum absorption/emission at 942/1302 nm. Results indicated that the styrene bridge and the N,N-dimethylamino electron donor in the design of NIR dyes can effectively induce red-shifted absorption/emission.…”