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.
Carbon
dots (CDs) as an emerging type of carbon nanomaterials exhibit
great potential in bioimaging applications owing to their superior
optical properties and excellent biocompatibility. However, it is
still challenging to fabricate sole carbon dots with integrated functionalities
of diagnostic and therapeutic modalities. Herein, we developed a facile
strategy to prepare the ruthenium-containing carbon dots (Ru-CDs)
via a hydrothermal method using the 5-amino-1,10-phenanthroline ruthenium(II)
complex (Ru-Aphen) and citric acid as starting materials. The structure
and morphology of Ru-CDs were verified by transmission electron spectroscopy,
X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform
infrared spectra. The Ru-CDs exhibited good water solubility, intense
red emission, and efficient reactive oxygen species (ROS) generation.
The MTT assay against HeLa cells demonstrated favorable biocompatibility
and distinct photodynamic effect of Ru-CDs. Owing to strong luminescence
in water (QY = 20.79%) and efficient ROS generation, Ru-CDs were not
only applied as bioimaging agents for tumor cells and zebrafish embryos,
but also as photodynamic nanoagents for cancer therapy. Finally, the
DNA photocleavage of Ru-CDs was verified through the experiment of
gel electrophoresis. The results suggested that the plasmid DNA could
only be damaged in the presence of Ru-CDs and light. Thus, the as-prepared
Ru-CDs showed good prospects and a wide range of biological applications.
Photosensitizers are light-sensitive molecules that are highly hydrophobic, which poses a challenge to their use for photodynamic therapy. Hence, considerable efforts have been made to develop carriers for the delivery of PSs. Herein, we synthesized a new theranostic nanoagent (CQDs@PtPor) through the electrostatic interaction between the tetraplatinated porphyrin complex (PtPor) and the negatively charged CQDs. The size and morphology of as-prepared CQDs and CQDs@PtPor were characterized by a series of methods, such as XRD, TEM, XPS, and FTIR spectroscopy. The CQDs@PtPor composite integrates the optical properties of CQDs and the anticancer function of porphyrin into a single unit. The spectral results suggested the effective resonance energy transfer from CQDs to PtPor in the CQDs@PtPor composite. Impressively, the CQDs@PtPor composite showed the stronger PDT effect than that of organic molecular PtPor, suggesting that CQDs@PtPor is advantageous over the conventional formulation, attributable to the enhanced efficiency of 1O2 production of PtPor by CQDs. Thus, this CQDs-based drug nanocarrier exhibited enhanced tumor-inhibition efficacy as well as low side effects in vitro, showing significant application potential in the cancer therapy.Electronic supplementary materialThe online version of this article (10.1186/s11671-018-2761-5) contains supplementary material, which is available to authorized users.
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