Extensive recent progress has been made on the design and applications of organic photothermal agents for biomedical applications because of their excellent biocompatibility comparing with inorganic materials. One major hurdle for the further development and applications of organic photothermal agents is the rarity of high‐performance materials in the second near‐infrared (NIR‐II) window, which allows deep tissue penetration and causes minimized side effects. Up till now, there have been few reported NIR‐II‐active photothermal agents and their photothermal conversion efficiencies are relatively low. Herein, optical absorption of π‐conjugated small molecules from the first NIR window to the NIR‐II window is precisely regulated by molecular surgery of substituting an individual atom. With this technique, the first demonstration of a conjugated oligomer (IR‐SS) with an absorption peak beyond 1000 nm is presented, and its nanoparticle achieves a record‐high photothermal conversion efficiency of 77% under 1064 nm excitation. The nanoparticles show a good photoacoustic response, photothermal therapeutic efficacy, and biocompatibility in vitro and in vivo. This work develops a strategy to boost the light‐harvesting efficiency in the NIR‐II window for cancer theranostics, offering an important step forward in advancing the design and application of NIR‐II photothermal agents.
Photoacoustic (PA) imaging and tracking
of stem cells plays an
important role in the real-time assessment of cell-based therapies.
Nevertheless, the limitations of conventional inorganic PA contrast
agents and the narrow range of the excitation wavelength in the first
near-infrared (NIR-I) window hamper the applications of PA imaging
in living subjects. Herein, we report the design and synthesis of
a second near-infrared (NIR-II) absorptive organic semiconducting
polymer (OSP)-based nanoprobe (OSPN+) for PA imaging and
tracking of stem cells. Comparison studies in biological tissue show
that NIR-II light excited PA imaging of the OSPN+ has significantly
higher signal-to-noise ratio than NIR-I light excited PA imaging,
thereby demonstrating the superiority of the OSPN+ for
deep tissue imaging. With good biocompatibility, appropriate size,
and optimized surface property, the OSPN+ shows enhanced
cellular uptake for highly efficient PA labeling of stem cells. In vivo investigations reveal significant NIR-II PA contrast
enhancement of the transplanted OSPN+-labeled human mesenchymal
stem cells by 40.6- and 21.7-fold in subcutaneous and brain imaging,
respectively, compared with unlabeled cases. Our work demonstrates
a class of OSP-based nanomaterials for NIR-II PA stem cell imaging
to facilitate a better understanding and evaluation of stem cell-based
therapies.
Precise
diagnosis and effective treatment of gliomas still remain
a huge challenge. Photoacoustic-guided photothermal therapy (PTT)
has unique advantages over conventional techniques for brain tumor
theranostics, but existing nanoagents for photoacoustic imaging (PAI)-guided
PTT are mainly organic small molecules or inorganic nanoparticles,
which have the limitations of poor photostability and biocompatibility.
Besides, the restricted absorption in the first near-infrared window
(NIR-I) of the most existing nanoagents compromises their effectiveness
for deep tissue PAI and PTT. We herein develop novel semiconducting
polymer nanoparticles (SPNs) that are strongly absorptive in the second
NIR window (NIR-II) to alleviate these problems. With the merits of
excellent photoacoustic and photothermal performance, high photostability,
proper size, and low toxicity, SPNs not only show efficient cellular
uptake for PAI and PTT toward U87 glioma cells but also demonstrate
effective accumulation in both subcutaneous tumors and brain tumors
upon intravenous injection, thereby realizing efficient PAI-guided
PTT toward gliomas under NIR-II light irradiation.
Immunotherapy is an effective treatment for many cancer types. However, YTHDF2 effects on the prognosis of different tumors and correlation with tumor immune infiltration are unclear. Here, we analyzed The Cancer Genome Atlas and Gene Expression Omnibus data obtained through various web-based platforms. The analyses showed that YTHDF2 expression and associated prognoses may depend on cancer type. High YTHDF2 expression was associated with poor overall survival in lower-grade glioma (LGG). In addition, YTHDF2 expression positively correlated with expression of several immune cell markers, including PD-1, TIM-3, and CTLA-4, as well as tumor-associated macrophage gene markers, and isocitrate dehydrogenase 1 in LGG. These findings suggest that YTHDF2 is a potential prognostic biomarker that correlates with LGG tumor-infiltrating immune cells.
Excellent yields were obtained from the silver nitrate-catalyzed homocoupling reaction of alkynes in N,N-dimethylformamide using triphenylphosphine as ligand. This safe and simple silver catalytic system has been employed in a safe and efficient protocol for the synthesis of various 1,3-diyne products from the corresponding aromatic or aliphatic alkynes with good air stability and absence of side products.
Developing
probes to simultaneously detect and discriminate biothiols
is important, yet challenging. Activatable photoacoustic (PA) probes
for discriminating biothiols in vivo are still lacking,
and this hinders the diagnosis of thiol-related diseases. Herein we
present the first PA and fluorescence dual-modality probe MB-NBD for discriminating different biothiol species.
The probe has the advantages of both fluorescence imaging and PA imaging
(high sensitivity and deep penetration) with distinct signal patterns
toward hydrogen sulfide (H2S), cysteine/homocysteine (Cys/Hcy),
and glutathione (GSH) treatment. The biothiol-activated product of MB-NBD exhibits enhancements in near-infrared fluorescence
(NIRF) at 690 nm and absorbance/PA at 664 nm upon fast reaction, allowing
it to selectively detect biothiol species over other reactive species.
On the other hand, MB-NBD displays characteristic
absorbance enhancement at 547 nm toward H2S, rendering
specific detection of H2S. In addition, the specific enhancements
in absorbance/PA at 470 nm and fluorescence at 550 nm toward Cys/Hcy
treatment endows the probe with the capability of selectively detecting
Cys/Hcy. Furthermore, MB-NBD is able to
discriminate Cys and GSH by fluorescent imaging in live-cell and ratiometric
PA imaging in mice experiments. MB-NBD has been successfully
used to diagnose tumors by dual-channel ratiometric PA imaging.
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