Fluorescence imaging with high sensitivity and minimal invasiveness has received tremendous attention, which can accomplish visualized monitoring and evaluation of cancer progression. Compared with the conventional first near‐infrared (NIR‐I) optical window (650–950 nm), fluorescence imaging in the second NIR optical window (NIR‐II, 950–1700 nm) exhibits deeper tissue penetration capability and higher temporal‐spatial resolution with lower background interference for achieving deep‐tissue in vivo imaging and real‐time monitoring of cancer development. Encouraged by the significant preponderances, a variety of multifunctional NIR‐II fluorophores have been designed and fabricated for sensitively imaging biomarkers in vivo and visualizing the treatment procedure of cancers. In this review, the differences between NIR‐I and NIR‐II fluorescence imaging are briefly introduced, especially the advantages of NIR‐II fluorescence imaging for the real‐time visualization of tumors in vivo and cancer diagnosis. An important focus is to summarize the NIR‐II fluorescence imaging for deep‐tissue biomarker analysis in vivo and tumor tissue visualization, and a brief introduction of NIR‐II fluorescence imaging‐guided cancer therapy is also presented. Finally, the significant challenges and reasonable prospects of NIR‐II fluorescence imaging for cancer diagnosis in clinical applications are outlined.
Metal–organic frameworks (MOF) have attracted
great potential
in sonodynamic therapy (SDT) owing to large sonosensitizers’
loading and fast reactive oxygen species’ (ROS) diffusion;
however, the low ligand-to-metal charge transfer efficiency sharply
impairs the SDT effect. Herein, we report the design of MIL@Ag heterostructures
with high electron–hole pairs separation efficiency and enhanced
diverse ROS generation ability for deep-seated cancer treatment and
bacterial infection. The MIL@Ag heterostructure is composed of Ti-based
MOFs (named MIL), on which are in situ assembled silver nanoparticles
(Ag NPs). The electrochemical experiments and density functional theory
calculations verify that the introduction of Ag NPs can significantly
improve the electron transfer efficiency and O2 adsorption
capacity of MIL. Under ultrasound irradiation, the doped Ag NPs can
trap the activated electrons from MIL to reduce surrounding O2 and produce superoxide radicals (•O2
–), while the activated holes enable oxidizing H2O to produce hydroxyl radicals (•OH). Thus, they efficiently
improve the therapeutic efficiency of SDT. MIL@Ag-PEG-mediated SDT
implements A549 cancer cells’ killing under a tissue barrier
of 2 cm and eradicates the bacterial infection of Staphylococcus
aureus, thus promoting wound healing. Therefore, MIL@Ag-PEG
provides a promising strategy for augmenting SDT performance by rational
heterostructure design of sonosensitizers.
Photothermal therapy allows spatiotemporal control of the treatment effect only at the site of the disease and provides promising opportunities for imaging-guided precision therapy. However, the development of photothermal transduction agents (PTAs) for tumor-specific accumulation and precision imaging, avoiding toxicity to the surrounding healthy tissue, is still challenging. Herein, a cyclooxygenase-2-specific small-organicmolecule-based PTA (Cy7-TCF-IMC) is developed, which can self-assemble into nanosaucers having unique photothermal and photoacoustic properties. Specifically, the self-assembling nature of Cy7-TCF-IMC affords preferential accumulation in tumors arising from synergistic passive enhanced permeability and retention effects and active targeting for precision theranostics. Antitumor therapy results show that these Cy7-TCF-IMC nanosaucers are highly photoacoustic imaging-guided PTAs for tumor ablation. These findings suggest the self-assembled Cy7-TCF-IMC nanosaucer represents a new paradigm as a single-component supramolecular medicine that can synergistically optimize passive and active targeting, thereby improving the therapeutic index of cancer and future clinical outcomes.
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