As the first line of host defense against invading pathogens, neutrophils have an inherent phagocytosis capability for the elimination of foreign agents and target loading upon activation, as well as the ability to transmigrate across blood vessels to the infected tissue, making them natural candidates to execute various medical tasks in vivo. However, most of the existing neutrophil-based strategies rely on their spontaneous chemotactic motion, lacking in effective activation, rapid migration, and high navigation precision. Here, we report an optically manipulated neutrophil microcraft in vivo through the organic integration of endogenous neutrophils and scanning optical tweezers, functioning as a native biological material and wireless remote controller, respectively. The neutrophil microcrafts can be remotely activated by light and then navigated to the target position along a designated route, followed by the fulfillment of its task in vivo, such as active intercellular connection, targeted delivery of nanomedicine, and precise elimination of cell debris, free from the extra construction or modification of the native neutrophils. On the basis of the innate immunologic function of neutrophils and intelligent optical manipulation, the proposed neutrophil microcraft might provide new insight for the construction of native medical microdevices for drug delivery and precise treatment of inflammatory diseases.
Based on the irregularly structured hydrogen bonded interpolymer complexes and their assembly, we obtained ellipsoidal polysaccharide vesicles. These vesicles not only exhibit uniform shape, but also regulate their shape and volume by transport channels like living cells.
Hypoxia plays a key role in tumor resistance to radiotherapy. It is important to study hypoxia dynamics during radiotherapy to improve treatment planning and prognosis. Here, we describe a luminescent nanoprobe, composed of a fluorescent semiconducting polymer and palladium complex, for quantitative longitudinal imaging of tumor hypoxia dynamics during radiotherapy. The nanoprobe was designed to provide high sensitivity and reversible response for the subtle change in hypoxia over a narrow range (0-30 mmHg O2), which spans the oxygen range where tumors have limited radiosensitivity. Following intravenous administration, the nanoprobe efficiently accumulated in and distributed across the tumor, including the hypoxic region. The ratio between emissions at 700 and 800 nm provided quantitative mapping of hypoxia across the entire tumor. The nanoprobe was used to image tumor hypoxia dynamics over 7 days during fractionated radiotherapy and revealed that high fractional dose (10 Gy) was more effective in improving tumor reoxygenation than low dose (2 Gy), and the effect tended to persist longer in smaller or more radiosensitive tumors. Our results also indicated the importance of the reoxygenation efficiency of the first fraction in the prediction of the radiation treatment outcome. In summary, this work has established a new nanoprobe for highly sensitive, quantitative, and longitudinal imaging of tumor hypoxia dynamics following radiotherapy, and demonstrated its value for assessing the efficacy of radiotherapy and radiation treatment planning. SIGNIFICANCE: This study presents a novel nanoagent for the visualization and quantification of tumor hypoxia.
<div>Abstract<p>Hypoxia plays a key role in tumor resistance to radiotherapy. It is important to study hypoxia dynamics during radiotherapy to improve treatment planning and prognosis. Here, we describe a luminescent nanoprobe, composed of a fluorescent semiconducting polymer and palladium complex, for quantitative longitudinal imaging of tumor hypoxia dynamics during radiotherapy. The nanoprobe was designed to provide high sensitivity and reversible response for the subtle change in hypoxia over a narrow range (0–30 mmHg O<sub>2</sub>), which spans the oxygen range where tumors have limited radiosensitivity. Following intravenous administration, the nanoprobe efficiently accumulated in and distributed across the tumor, including the hypoxic region. The ratio between emissions at 700 and 800 nm provided quantitative mapping of hypoxia across the entire tumor. The nanoprobe was used to image tumor hypoxia dynamics over 7 days during fractionated radiotherapy and revealed that high fractional dose (10 Gy) was more effective in improving tumor reoxygenation than low dose (2 Gy), and the effect tended to persist longer in smaller or more radiosensitive tumors. Our results also indicated the importance of the reoxygenation efficiency of the first fraction in the prediction of the radiation treatment outcome. In summary, this work has established a new nanoprobe for highly sensitive, quantitative, and longitudinal imaging of tumor hypoxia dynamics following radiotherapy, and demonstrated its value for assessing the efficacy of radiotherapy and radiation treatment planning.</p>Significance:<p>This study presents a novel nanoagent for the visualization and quantification of tumor hypoxia.</p></div>
Highly sensitive and specific non-invasive molecular imaging methods are particularly desirable for the early detection of cancers. Here we report a near-infrared optical imaging probe highly specific to the hypoxic tumour microenvironment to detect tumour and cancer cells with the sensitivity to a few thousands cancer cells. This oxygen-sensitive, near-infrared emitting and water-soluble phosphorescent macromolecular probe can not only report the hypoxic tumour environment of various cancer models, including metastatic tumours in vivo, but can also detect a small amount of cancer cells before the formation of the tumour based on the increased oxygen consumption during cancer cell proliferation. Thus, the reported hypoxia-sensitive probe may offer an imaging tool for characterizing the tumour microenvironment in vivo, detecting cancer cells at a very early stage of tumour development and lymph node metastasis. As hypoxia is a hallmark of tumour microenvironment, hypoxia-sensing probes are used for tumour imaging. Here, the authors report a hypoxia probe with increased sensitivity, water solubility and functional pH range, allowing in vivodetection of early metastases as small as a few thousand cells.
Nanoparticles have been widely employed as contrast agents for various types of molecular imaging modalities due to their unique optical and magnetic properties. The surface functionalization of nanoparticles often determines their translatability and performance under biological conditions. Herein, we discuss several representative chemical approaches for modifying the major classes of nanoparticles including surface oxidation and cycloaddition on the unsaturated carbon-carbon bonds, surface chemistry based on metal-sulfur bonds, silica coating, surface-initiated polymerization, and surface cross-linking. Examples of these chemistries have been described by modifying the surface functionality of nanomaterials to improve their properties including water-solubility, chemical and biological stability, biocompatibility, antifouling property, blood circulation, biodistribution, specific targeting, and multimodal imaging abilities. The remaining challenges in the current chemical approaches for nanoparticle surface functionalization are also discussed.
Iron oxides nanoparticles tailored for magnetic particle imaging (MPI) have been synthesized, and their MPI signal intensity is three-times that of commercial MPI contrast (Ferucarbotran, also called Vivotrax) and seven-times that of MRI contrast (Feraheme) at the same Fe concentration. MPI tailored iron oxide nanoparticles were encapsulated with semiconducting polymers to produce Janus nanoparticles that possessed optical and magnetic properties for MPI and fluorescence imaging. Janus particles were applied to cancer cell labeling and in vivo tracking, and as few as 250 cells were imaged by MPI after implantation, corresponding to an amount of 7.8 ng of Fe. Comparison with MRI and fluorescence imaging further demonstrated the advantages of our Janus particles for MPI-super sensitivity, unlimited tissue penetration, and linear quantitativity.
<div>Abstract<p>Hypoxia plays a key role in tumor resistance to radiotherapy. It is important to study hypoxia dynamics during radiotherapy to improve treatment planning and prognosis. Here, we describe a luminescent nanoprobe, composed of a fluorescent semiconducting polymer and palladium complex, for quantitative longitudinal imaging of tumor hypoxia dynamics during radiotherapy. The nanoprobe was designed to provide high sensitivity and reversible response for the subtle change in hypoxia over a narrow range (0–30 mmHg O<sub>2</sub>), which spans the oxygen range where tumors have limited radiosensitivity. Following intravenous administration, the nanoprobe efficiently accumulated in and distributed across the tumor, including the hypoxic region. The ratio between emissions at 700 and 800 nm provided quantitative mapping of hypoxia across the entire tumor. The nanoprobe was used to image tumor hypoxia dynamics over 7 days during fractionated radiotherapy and revealed that high fractional dose (10 Gy) was more effective in improving tumor reoxygenation than low dose (2 Gy), and the effect tended to persist longer in smaller or more radiosensitive tumors. Our results also indicated the importance of the reoxygenation efficiency of the first fraction in the prediction of the radiation treatment outcome. In summary, this work has established a new nanoprobe for highly sensitive, quantitative, and longitudinal imaging of tumor hypoxia dynamics following radiotherapy, and demonstrated its value for assessing the efficacy of radiotherapy and radiation treatment planning.</p>Significance:<p>This study presents a novel nanoagent for the visualization and quantification of tumor hypoxia.</p></div>
A series of phosphorescent probes have been developed based on the iridium(iii) complexes and bio-compatible polymers for imaging hypoxia and cancer metastasis in vivo. These macromolecular or nano-sized probes exhibited near-infrared (NIR) phosphorescence emission as well as high sensitivity and specificity to hypoxia. By using non-invasive optical imaging with these phosphorescent probes, semi-quantitative measurement of tumour hypoxia and long-term observation of cancer cell proliferation in vivo have been achieved. With the tailored design for the imaging of cancer metastasis, the probes have been successfully applied for tracking various kinds of cancer metastasis in the animal models, including lung metastasis, lymph node metastasis and liver metastasis. The imaging of cancer metastasis with these probes has exhibited excellent contrast with high signal-to-noise-ratio (SNR 10 to 60) and high specificity in comparison to signals from normal tissues. These iridium(iii) complex-based phosphorescent probes provide significant advantages over the conventional hypoxia imaging contrast agents such as the nitro-imidazole derivatives in terms of high imaging sensitivity, specificity, and radiation-free quantitative measurement. The ability of these probes in tracking cancer metastasis makes them promising for such further applications as cancer diagnosis and image-guided surgery.
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