Small-Molecule Porphyrin-Based Organic Nanoparticles with Remarkable Photothermal Conversion Efficiency for in Vivo Photoacoustic Imaging and Photothermal Therapy

Abstract

Near-infrared (NIR)-absorbing organic nanoparticles (ONPs) are emerging candidates for “one-for-all” theranostic nanomaterials with considerations of safety and formulation in mind. However, facile fabrication methods and improvements in the photothermal conversion efficiency (PCE) and photostability are likely needed before a clinically viable set of candidates emerges. Herein, a new organic compound, [porphyrin–diketopyrrolopyrrole (Por–DPP)] with the donor–acceptor structure was synthesized, where porphyrin was used as a donor unit while diketopyrrolopyrrole was used as an acceptor unit. Por–DPP exhibited efficient absorption extending from visible to NIR regions. After self-assembling into nanoparticles (NPs) (∼120 nm), the absorption spectrum of Por–DPP NPs broadened and red-shifted to some extent, relative to that of organic molecules. Furthermore, the architecture of NPs enhanced the acceptor–donor structure, leading to emission quenching and facilitating nonradiative thermal generation. The PCE of Por–DPP NPs was measured and calculated to be 62.5%, higher than most of ONPs. Under 808 nm laser irradiation, the Por–DPP NPs possessed a distinct photothermal therapy (PTT) effect in vitro and can damage cancer cells efficiently in vivo without significant side effects after phototherapy. Thus, the small-molecule porphyrin-based ONPs with high PCE demonstrated promising application in photoacoustic imaging-guided PTT.

An Acceptor-π-Donor Structured Organic Chromophore for NIR Triggered Thermal Ablation of Tumor via DNA Damage-Mediated Apoptosis

“…As depicted in Figure 1D, when the concentration of PTM NPs reached 160 μg/mL, the solution temperature rose rapidly to 72.4°C under NIR laser irradiation (808 nm, 1.5 W/cm 2 , 10 min). It is worth noting that PTM NPs also reached effective hyperthermia (45 °C) with the concentration of 40 μg/ mL under the same conditions, demonstrated that PTM The photothermal conversion efficiency of PTM NPs was evaluated to be ~56.9% according to the reported method (Figure S9), 53 which is significantly superior to most previously reported photothermal reagents, including porphyrin (62.5%), 54 phthalocyanine-based nanodots (45.7%), 55 cyanine dyes (26.6%), 56 polypyrrole NPs (45%), 57 dopamine-melanin NPs (40%), 58 Au nanorods (21.0%), 59 MoS 2 nanosheets (24.4%). 60 All these results confirmed that PTM NPs can act as a promising candidate for photothermal therapy.…”

Supramolecular Photothermal Effects: A Promising Mechanism for Efficient Thermal Conversion

“…Notably, aggregation‐caused thermal release is also effective for semiconductive polymeric materials, which are usually designed by covalent conjugation of donor and acceptor units. Such polymers enable both intramolecular and intermolecular charge transfer, which significantly inhibits emission and, in turn, enhances the photothermal conversion efficiency . For example, Pu and co‐workers developed a semiconducting copolymer poly[(diketopyrrolopyrrole‐ alt ‐cyclopentadithiophene)‐ ran ‐(diketopyrrolopyrrole‐ alt ‐thiadiazoloquinoxaline)] (PDCDT) containing two segments which showed absorption in different NIR windows (Figure b) .…”

Polymer encapsulated clinical ICG nanoparticles for enhanced photothermal therapy and NIR fluorescence imaging in cervical cancer

“…12,13 PTN are one key reason for effective PTT. [14][15][16] To achieve high PTT efficiency, PTN with biocompatible, NIR emissive and well photothermal properties are favorable. [17][18][19] Indocyanine Green (ICG) is a clinically relevant contrast agent which is approved by the Food and Drug Administration (FDA).…”