Generating long‐wavelength absorption bands with enhanced deep red fluorescence and photothermal performance in fused carbon dots aggregates

Abstract

Carbon dots (CDs) with long‐wavelength absorptions and emissions are highly desired for biological applications. Herein, we report a new supra‐CDs strategy to construct long‐wavelength absorption bands based on fused CDs aggregates (f‐CDAs) through a concentration‐induced interparticle dehydration process among green emissive CDs (r‐CDs) under solvothermal treatment. The obtained fused f‐CDAs exhibit an obvious absorption band in 550–700 nm and significantly enhanced deep red fluorescence in N,N‐dimethylformamide with photoluminescence quantum yields of 15.6% and high photothermal conversion efficiency up to 26.1% in water. Benefiting from the high photothermal performance, in vivo tumor photothermal therapy has been realized via intratumoral injection of f‐CDAs under 655 nm laser irradiated at 0.5 W/cm2.

Regulating photochemical properties of carbon dots for theranostic applications

“…CIOMP). (h) Schematic representation of fluorescence in F‐CDAs from Wu et al (2021). Copyright 2021.…”

“…Owning to high 1 O 2 QY of 0.45, CDNs can be applied in NIR fluorescence imaging and PDT. Wu et al (2021) prepared fused aggregates of CDs (F‐CDAs) besides forming self‐assembling aggregates of CDs via the solvothermal treatment of the green‐emitted CDs, which exhibited excellent photothermal performance (Figure 3h). The long‐wavelength emission and the absorption band of F‐CDAs formed by the dehydration of high concentrations of carboxyl and hydroxyl groups on the surface of green‐emitted CDs were a result of the interface of a molten aggregate of the CDs consisting of electron‐donating and electron‐withdrawing groups in proximity.…”

Tuning the photothermal properties of carbon dots in the deep-red to near-infrared wavelength regions for tumor therapy

“…In recent years, carbon dots (CDs), owing to their broadband absorption, well-documented biocompatibility, high photostability, and lower toxicity, have met nearly all these criteria and are therefore considered potential photothermal agents in cancer therapy. [15][16][17][18][19][20][21] To realize low-degree photon scattering, less absorption from living tissues, and deeper penetration, in vivo long-wavelength absorption, particularly in the biological transparency window of 650-1800 nm, is highly desired. For CDs, strong UV to green absorption bands have been extensively reported and synthetically developed, while studies on CDs with efficient deep-red (DR) or near-infrared (NIR) absorption bands are limited.…”

Toward Strong Near‐Infrared Absorption/Emission from Carbon Dots in Aqueous Media through Solvothermal Fusion of Large Conjugated Perylene Derivatives with Post‐Surface Engineering

“…[ 13 ] Although their particle sizes can be much larger than 2 nm, their main absorption bands are always observed in the UV or visible regions, indicating smaller conjugated sp 2 domains in the carbon cores. [ 14 ] Thus, carbon cores with large conjugation are thought to be the primary factor for CDs with both main NIR absorption/emission in aqueous solution.…”