Triglyceride-Rich Lipoprotein-Mediated Polymer Dots for Multimodal Imaging Interscapular Brown Adipose Tissue Capillaries.

Brown adipose tissues (BATs) have been identified as a promising target of metabolism disorders. [18F]FDG-PET (FDG = fluorodeoxyglucose; PET = positron emission tomography) has been predominantly employed for BAT imaging, but its limitations drive the urgent need for novel functional probes combined with multimodal imaging approaches. It has been reported that polymer dots (Pdots) display rapid BAT imaging without additional cold stimulation. However, the mechanism by which Pdots image BAT remains unclear. Here, we made an intensive study of the imaging mechanism and found that Pdots can bind to triglyceride-rich lipoproteins (TRLs). By virtue of their high affinity to TRLs, Pdots selectively accumulate in capillary endothelial cells (ECs) in interscapular brown adipose tissues (iBATs). Compared to poly(styrene-co-maleic anhydride)cumene terminated (PSMAC)-Pdots with a short half-life and polyethylene glycol (PEG)-Pdots with low lipophilicity, naked-Pdots have good lipophilicity, with a half-life of about 30 min and up to 94% uptake in capillary ECs within 5 min, increasing rapidly after acute cold stimulation. These results suggested that the accumulation changes of Pdots in iBAT can reflect iBAT activity sensitively. Based on this mechanism, we further developed a strategy to detect iBAT activity and quantify the TRL uptake in vivo using multimodal Pdots.

High-Resolution Imaging of the Ocular Vasculature of Conjunctivitis in Mice Using Highly Bright Polymer Dots.

Ocular diseases are mainly caused by vascular aberrations in the eye, and accurate imaging and analysis of the ocular vascular structure is crucial. In this study, poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PFBT) polymer dots (Pdots), with the advantages of easy synthesis, high brightness, and low toxicity, are used as nanoprobes to perform high-resolution imaging of the vasculature of the eyeball and optic nerve. Moreover, rapid imaging of the choroidal microvessels is carried out by stereoscopic fluorescence microscopy with a resolution of up to 1.6 µm. The comprehensive 3D vascular information of retinal aorta and optic nerve microvessels is obtained by combining tissue clearing and multiphoton microscopy. In addition, the vascular density of Schlemm's canal and iris blood vessels is compared between the conjunctivitis mice and the normal mice. These results suggest that PFBT Pdots have great application potential in the fast and accurate imaging of ocular diseases.

Multifunctional Imaging of Vessels, Brown Adipose Tissue, and Bones in the Visible and Second Near-infrared Region Using Dual-Emitting Polymer Dots.

Dual-emitting polymer dots (dual-Pdots) in the visible and second near-infrared (NIR-II) region can facilitate the high-resolution imaging of the fine structure and improve the signal-to-noise ratio in in vivo imaging. Herein, combining high brightness of Pdots and multi-scale imaging, we synthesized dual-Pdots using a simple nano-coprecipitation method and performed multi-functional imaging of vessels, brown adipose tissue, and bones. Results showed that in vivo blood vessel imaging had a high resolution of up to 5.9 µm and bone imaging had a signal-to-noise ratio of 3.9. Moreover, dual-Pdots can accumulate in the interscapular brown adipose tissue within 2 min with a signal-to-noise ratio of 5.8. In addition, the prepared dual-Pdots can image the lymphatic valves and the frequency of contraction. Our study provides a feasible method of using Pdots as nanoprobes for multi-scale imaging in the fields of metabolic disorders, skeletal system diseases, and circulatory systems.

Imaging of fluorescent polymer dots in relation to channels and immune cells in the lymphatic system.

Polymer dots (Pdots) have been applied to imaging lymph nodes (LNs) and lymphatic vessels (LVs) in living mice and rats. However, the mechanism of absorption, distribution, metabolism, and excretion of Pdots in LNs and LVs is still unclear. Therefore, the relationship between Pdots and immune cells, LVs and collagen fibers in lymphatics was studied by multiple in vivo and ex vivo microscopic imaging methods and detection techniques. Flow cytometry showed that Pdots could be phagocytosed by macrophages and monocytes, and had no relationship with B cells, T cells and dendric cells in LNs. Silver staining, immunofluorescence and two-photon microscope showed that Pdots gathered in collagen fibers and LVs of LNs. Furthermore, immunofluorescence imaging results verified that Pdots were distributed in the extracellular space of collecting LVs endothelial cells. In addition, Pdots in the collecting LVs were basically cleared by leaking into the surrounding tissue or draining LNs after 21 days of injection. During the long-time observation, Pdots also helped monitor the contraction frequency and variation range of LV. Our study lays a foundation on the research of Pdots as the carrier to study lymphatic structure and function in the future.

Tumor microenvironment-responsive nanohybrid for hypoxia amelioration with photodynamic and near-infrared II photothermal combination therapy.

Phototherapy, particularly photothermal therapy (PTT) and photodynamic therapy (PDT), has been widely investigated for tumor treatment. However, the limited tissue penetration depth of light in the near-infrared I (NIR-I) region and the hypoxic tumor microenvironment (TME) severely constrain their clinical applications. To address these challenges, in the present study, we developed a chlorin e6 (Ce6) and MnO2-coloaded, hyaluronic acid (HA)-coated single-walled carbon nanohorns (SWNHs) nanohybrid (HA-Ce6-MnO2@SWNHs) for PDT and PTT combination therapy of tumor. HA-Ce6-MnO2@SWNHs responded to the mild acidic TME to ameliorate tumor hypoxia, thus enhancing tumor PDT. Moreover, HA-Ce6-MnO2@SWNHs had a high photothermal conversion efficiency at 1064 nm (55.48%), which enabled deep tissue penetration (3.05 cm) and allowed for highly efficient tumor PTT in near-infrared II (NIR-II) window. PDT and PTT combination therapy with HA-Ce6-MnO2@SWNHs achieved a good therapeutic efficacy on 4T1 tumor-bearing mice, eradicating the primary tumors and suppressing cancer recurrence. Our study provides a promising strategy for developing a hypoxia relief and deep tissue penetration phototherapy platform by using SWNHs for highly effective tumor PDT and NIR-II PTT combination therapy. STATEMENT OF SIGNIFICANCE: The hypoxic tumor microenvironment (TME) and the limited penetration of the NIR-I light in biological tissues compromise the efficacy of photothermal therapy (PTT) and photodynamic therapy (PDT) on tumors. Here, we developed a chlorin e6 (Ce6) and MnO2-coloaded, hyaluronic acid (HA)-coated single-walled carbon nanohorns (SWNHs) nanohybrid (HA-Ce6-MnO2@SWNHs) for PDT and PTT combination therapy of tumors. The nanohybrid could efficiently accumulate in tumors through CD44-mediated active targeting. The sequential MnO2-enhanced PDT and efficient NIR-II PTT had a remarkable therapeutic effect by eliminating the primary tumor and simultaneously inhibiting tumor recurrence.

Metabolic Control by Heat Stress Determining Cell Fate to Ferroptosis for Effective Cancer Therapy.

Flexible manipulation of the fate of cancer cells through exogenous stimulation-induced metabolic reprogramming could handle the cellular plasticity-derived therapies resistance, which provides an effective paradigm for the treatment of refractory and relapsing tumors in clinical settings. Herein, we demonstrated that moderate heat (45 °C) could significantly regress the expression of antioxidants and trigger specific lipid metabolic reprogramming in cancer cells synergized with iron oxide nanoparticles (Fe3O4 NPs). This metabolic control behavior destroyed the tumor redox homeostasis and produced overwhelming lipid peroxides, consequently sensitizing the tumor to ferroptosis. Based on these findings, a heat-triggered tumor-specific ferroptosis strategy was proposed by the rational design of a polypeptide-modified and 1H-perfluoropentane (1H-PFP)-encapsulated Fe3O4-containing nanoformulation (GBP@Fe3O4). When irradiated by an 808 nm laser, the phase transition of 1H-PFP was triggered by localized moderate heat (45 °C), leading to burst release of Fe3O4in situ to produce potent reactive oxygen species through the Fenton reaction in the tumor microenvironment. Together with the antioxidant inhibition response and distinctive lipid metabolic reprogramming by heat stress, this oxidative damage was amplified to induce tumor ferroptosis and achieve sufficient antitumor effects. Importantly, we confirmed that ACSBG1, an acyl-CoA synthetase, was the key pro-ferroptotic factor in this heat-induced ferroptosis process. Moreover, knockout of this gene could realize cancer cell death fate conversion from ferroptosis to non-ferroptotic death. This work provides mechanistic insights and practical strategies for heat-triggered ferroptosis in situ to reduce the potential side effects of direct ferroptosis inducers and highlights the key factor in regulating cell fate under heat stress.

NIR/photoacoustic imaging of multitype gallbladder cancer using carboxyl/amino functionalized polymer dots.

Gallbladder cancer has high incidence and mortality and a low early diagnosis rate and requires rapid and efficient diagnosis. Herein, carboxyl/amino functionalized polymer dots (Pdots) were designed to enhance cellular internalization and tumor accumulation. The prepared Pdots were 40-50 nm in diameter, contained no toxic metal, exhibited long circulation time and high stability, and produced strong NIR emission and photoacoustic signals. Different cellular uptake and distribution of functionalized Pdots in eight gallbladder cell lines were quantitatively investigated using flow cytometry and super-resolution microscopy. In vivo NIR fluorescence imaging showed that the functional Pdots had high accumulation in the tumor after 30 minutes of injection and remained there for up to 6 days. In addition, photoacoustic imaging found that the abundant blood vessels around the tumor microenvironment and Pdots entered the tumor through the blood vessels. Furthermore, a high heterogeneity of vascular networks was visualized in real-time and high resolution by probe-based confocal laser endomicroscopy imaging. These results offer a new avenue for the development of functional Pdots as a probe for multi-modal and multi-scale imaging of gallbladder cancer in small animals.

A self-immobilizing near-infrared fluorogenic probe for sensitive imaging of extracellular enzyme activity in vivo.

Reported herein is a self-immobilizing near-infrared fluorogenic probe that can be used to image extracellular enzyme activity in vivo. Using a fluorophore as a quinone methide precursor, this probe covalently anchors at sites of activation and greatly enhances the fluorescence intensity at 710 nm upon enzymatic stimulus, significantly boosting detection sensitivity in a highly dynamic in vivo system.

Sequential PDT and PTT Using Dual-Modal Single-Walled Carbon Nanohorns Synergistically Promote Systemic Immune Responses against Tumor Metastasis and Relapse.

Immune responses stimulated by photodynamic therapy (PDT) and photothermal therapy (PTT) are a promising strategy for the treatment of advanced cancer. However, the antitumor efficacy by PDT or PTT alone is less potent and unsustainable against cancer metastasis and relapse. In this study, Gd3+ and chlorin e6 loaded single-walled carbon nanohorns (Gd-Ce6@SWNHs) are developed, and it is demonstrated that they are a strong immune adjuvant, and have high tumor targeting and penetration efficiency. Then, three in vivo mouse cancer models are established, and it is found that sequential PDT and PTT using Gd-Ce6@SWNHs synergistically promotes systemic antitumor immune responses, where PTT stimulates dendritic cells (DCs) to secrete IL-6 and TNF-α, while PDT triggers upregulation of IFN-γ and CD80. Moreover, migration of Gd-Ce6@SWNHs from the targeted tumors to tumor-draining lymph nodes sustainably activates the DCs to generate a durable immune response, which eventually eliminates the distant metastases without using additional therapeutics. Gd-Ce6@SWNHs intervened phototherapies also generate durable and long-term memory immune responses to tolerate and prevent cancer rechallenge. Therefore, this study demonstrates that sequential PDT and PTT using Gd-Ce6@SWNHs under moderate conditions elicits cooperative and long-lasting antitumor immune responses, which are promising for the treatment of patients with advanced metastatic cancers.

The Effect of Polymer Dots During Mammalian Early Embryo Development and Their Biocompatibility on Maternal Health.

Conjugated polymer dots have excellent fluorescence properties in terms of their structural diversity and functional design, showing broad application prospects in the fields of biological imaging and biosensing. Polymer dots contain no heavy metals and are thought to be of low toxicity and good biocompatibility. Therefore, systematic studies on their potential toxicity are needed. Herein, the biocompatibility of poly[(9,9-dioctylfluorenyl-2,7diyl)-co-(1,4-benzo-{2,1',3}-thiadiazole)],10% benzothiadiazole(y) (PFBT) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) polymer dots on early embryo development as well as maternal health is studied in detail. The results show that prepared polymer dots are dose-dependently toxic to preimplantation embryos, and low-dose polymer dots can be used for cell labeling of early embryos without affecting the normal development of embryos into blastocysts. In addition, the in vivo distribution data show that the polymer dots accumulate mainly in the maternal liver, spleen, kidney, placenta, ovary, and lymph nodes of the pregnant mice. Histopathological examination and blood biochemical tests demonstrate that exposure of the maternal body to polymer dots at a dosage of 14 µg g-1 does not affect the normal function of the maternal organs and early fetal development. The research provides a safe basis for the wide application of polymer dots.

Toxicity, uptake and transport mechanisms of dual-modal polymer dots in penny grass (Hydrocotyle vulgaris L.).

The use of polymers such as plastic has become an important part of daily life, and in aqueous environments, these polymers are considered as pollutants. When macropolymers are reduced to the nanoscale, their small particle size and large specific surface area facilitate their uptake by plants, which has a significant impact on aquatic plants. Therefore, it is essential to study the pollution of nanoscale polymers in the aquatic environment. In this work, we prepared nanoscale polymer dots (Pdots) and explored their toxicity, uptake and transport mechanisms in penny grass. From toxicological studies, in the absence of other nutrients, the cell structure, physiological parameters (total soluble protein and chlorophyll) and biochemical parameters (malondialdehyde) do not show significant changes over at least five days. Through in vivo fluorescence and photoacoustic (PA) imaging, the transport location can be visually detected accurately, and the transport rate can be analyzed without destroying the plants. Moreover, through ex vivo fluorescence imaging, we found that different types of Pdots have various uptake and transport mechanisms in stems and blades. It may be due to the differences in ligands, particle sizes, and oil-water partition coefficients of Pdots. By understanding how Pdots interact with plants, a corresponding method can be developed to prevent them from entering plants, thus avoiding the toxicity from accumulation. Therefore, the results of this study also provide the basis for subsequent prevention work.

EDTA-Modified 17ß-Estradiol-Laden Upconversion Nanocomposite for Bone-Targeted Hormone Replacement Therapy for Osteoporosis.

Hormone therapy (HT) is one of the most effective treatments for osteoporosis. However, the nonselective accumulation of hormone in organs such as breast, heart and uterus other than bones causes serious side effects, which impedes the application of HT. Hence, it is critically important to develop a HT strategy with reduced non-specific enrichment of hormone drugs in non-target tissues and enhanced bone-targeting ability. Methods: Herein, a 17ß-estradiol (E2)-laden mesoporous silica-coated upconversion nanoparticle with a surface modification of ethylenediaminetetraacetic acid (EDTA) (NaLuF4:Yb,Tm@NaLuF4@mSiO2-EDTA-E2, E2-csUCNP@MSN-EDTA) is developed for bone-targeted osteoporosis hormone therapy. EDTA was attached onto the surface of E2 upconversion nanocomposite to enhance its affinity and efficiency targeting bone tissue and cells to optimize hormone replacement therapy for osteoporosis. We characterized the size, cytotoxicity, loading and release efficiency, in situ and ex vivo imaging. Further, in vitro and in vivo osteogenic ability was tested using preosteoblast and ovariectomy mouse model of osteoporosis. Results: The upconversion core of E2-csUCNP@MSN-EDTA nanoparticle serves as an excellent imaging agent for tracking the loaded hormone drug in vivo. The mesoporous silica layer has a high loading efficiency for E2 and provides a relatively long-lasting drug release within 50 h. EDTA anchored on the silica layer endows the nanocomposite with a bone targeting property. The nanocomposite effectively reverses estrogen deficiency-induced osteoporosis and reduces the damage of hormone to the uterus. The bone mineral density in the nanocomposite treatment group is nearly twice that of the ovariectomized (OVX) group. Compared with the E2 group, the uterine weight and luminal epithelial height were significantly lower in the nanocomposite treatment group. Conclusion: This work demonstrated that E2-csUCNP@MSN-EDTA alleviates the side effect of hormone therapy while maintaining its therapeutic efficacy, which has great potential for developing the next generation of methods for osteoporosis treatment.

Near-Infrared Polymer Dots in the Portal-Hepatic Circulation Achieve Localization of Hepatic Carcinoma In Vivo.

The present study aims to use polymer dots to explore whether they can visualize tumor lesions in a diethylnitrosamine (DENA)-induced hepatocellular carcinoma (HCC) model. The HCC rat model was set up, and serum liver function indexes and AFP were tested on days 0, 30, 60, and 90 of the modeling process. After characterization of the polymer dots, they were injected into the rats and mice. The liver, spleen, and kidney of rats and the gallbladder of mice were extracted to verify the metabolic pathways of the polymer dots and their capability of fluorescent localization of HCC and gallbladder by fluorescence imaging. Strong fluorescent emission from the liver appeared immediately and 15 min after the polymer dots were injected through the main portal veins and tail veins of the model rats, respectively. A satisfactory fluorescent imaging effect lasted up to 45 min. Polymer dots circulate through the bloodstream within intrahepatic vessels rather than intracellular areas and can be clearly visualized by using both the pCLE and IVIS spectrum imaging systems. Contrast imaging of HCC lesions without fluorescent emissions was due to the lack of normal portal-hepatic veins within the tumor areas. Fluorescent imaging of the gallbladder could also be detected at 15 min after the polymer dots were injected through the tail veins of mice. The polymer dots had satisfactory fluorescent localization capability for targeted intrahepatic vessels and HCC lesions in vivo and showed potential practical value in hepato-biliary surgery.

Tumor Chemo-Radiotherapy with Rod-Shaped and Spherical Gold Nano Probes: Shape and Active Targeting Both Matter.

The morphologies of gold nanoparticles (NPs) affect their tumor accumulation through enhanced permeability and retention effect. However, detailed information and mechanisms of NPs' characteristics affecting tumor accumulation are limited. The aim of this study is to evaluate the effects of shape and active targeting ligands of theranostic NPs on tumor accumulation and therapeutic efficacy, and to elucidate the underlying mechanism. Methods:αvß3 integrin-targeted, cisplatin-loaded and radioisotope iodine-125 labeled spherical and rod-shaped gold nano theranostic probes (RGD-125IPt-AuNPs and RGD-125IPt-AuNRs) with similar sizes were fabricated and characterized. The in vivo distribution and chemo-radio therapeutic efficacy against tumors of these newly developed probes were subsequently evaluated. Moreover, a physiologically based pharmacokinetic (PBPK) model was developed to characterize the in vivo kinetics of these probes at the sub-organ level, and to reveal the mechanism of NPs' shape and active targeting ligands effects on tumor accumulation. Result: Cisplatin and iodine-125 were loaded sequentially onto the NPs through a thin polydopamine coating layer on the NPs. Both RGD-125IPt-AuNPs and RGD-125IPt-AuNRs exhibited high specificity for αvß3 in vitro, with the rod-shaped probe being more efficient. The PBPK model revealed that rod-shaped gold NPs diffused more rapidly in tumor interstitial than the spherical ones. Tumor accumulations of non-targeted and rod-shaped RAD-125IPt-AuNRs was higher in short term (1 h post injection), but not pronounced and similar to that of non-targeted spherical RAD-125IPt-AuNPs in 24 h after intravenous injection, revealing that the NPs' shape did not have a significant impact on tumor accumulations through enhanced permeability and retention (EPR) effect in long-term. While for actively targeted NPs, in addition to a higher distribution coefficient, RGD-125IPt-AuNRs also had a much higher tumor maximum uptake rate constant than RGD-125IPt-AuNPs, indicating both the shape and active targeting ligands affected the tumor uptake of rod-shaped NPs. As a result, RGD-125IPt-AuNRs had a more effective inhibition of tumor growth than RGD-125IPt-AuNPs by chemo-radiationtherapy. Conclusion: Our study suggests that both the shape and active targeting ligands of gold NPs play important roles on tumor accumulation and chemo-radio therapeutic effect.

Fluorescent Polymer Dots for Tracking SKOV3 Cells in Living Mice with Probe-Based Confocal Laser Endomicroscopy.

PURPOSE: Probe-based confocal laser endomicroscopy (pCLE) is a novel technique allowing real-time and high-resolution imaging in vivo. It provides microscopic images and increases the penetration depth of tissues compared with conventional white light endoscopy. The aim of the present study was to track ovarian cancer cells in organs by fluorescent polymer dots based on pCLE. PROCEDURES: SKOV3-mCherry cells were incubated with polymer dots for 24 h in a serum-free culture medium. Labeled cells were administrated to nude mice via intravenous, intraperitoneal, and lymph node injection. The fluorescent signals of labeled cells in organs were observed by pCLE. Furthermore, the results were confirmed by frozen section analysis. RESULTS: pCLE displayed fluorescence signals of labeled cells in the vessels of organs. Besides, the accumulations of labeled cells visualized in detoxification organs like the spleen and kidney were increased with time. CONCLUSIONS: In this article, we present a real-time and convenient method for tracking SKOV3-mCherry in living mice by combined fluorescent polymer dots with pCLE.

High-Resolution Imaging of the Lymphatic Vascular System in Living Mice/Rats Using Dual-Modal Polymer Dots.

Noninvasive, repeated, and high-resolution imaging of the lymphatic vascular system plays an important role in studying the development and function of lymphatics. However, conventional imaging modality such as magnetic resonance imaging (MRI) and X-ray lymphangiography shows insufficient temporal and spatial resolution and can only visualize large lymphatic vessels. Herein, we developed polymer dots as a novel lymphatic agent for simultaneously imaging the lymphatic capillary plexus and collecting lymphatic vessels in living mice/rats at a fast temporal resolution and high spatial resolution by combination with probe-based confocal laser endomicroscopy (pCLE). The imaging effect was verified by whole-body near-infrared fluorescence and photoacoustic imaging as well as ex vivo two-photon microscope imaging. Our study provides a novel approach for using polymer dots for high-resolution lymphatic vascular imaging in small animals.

High resolution tracking of macrophage cells in deep organs and lymphatics using fluorescent polymer dots.

In vivo cell tracking can provide information on cell migration and accumulation in the organs. Here, both folate and amino modified polymer dots were synthesized and screened for in vitro and in vivo tracking of macrophage Ana-1 cells. Flow cytometry analysis demonstrated that prepared polymer dots showed cellular uptake of approximately 98% within a short incubation time of 2 h, and these polymer dots maintained a cell labeling rate over 97% after 2 d. Moreover, a CCK-8 assay suggested that these polymer dots increased Ana-1 cell viabilities up to 110% at concentrations from 5 to 50 µg mL-1. Furthermore, the in vivo real time imaging of labelled Ana-1 cells in the alveolus of lung and lymph nodes were clearly detected by probe-based confocal laser endomicroscopy (pCLE). This study demonstrates a unique approach using polymer dots for real-time high resolution tracking of macrophage cells in deep organs and the lymphatic system.

Multiscale Imaging of Brown Adipose Tissue in Living Mice/Rats with Fluorescent Polymer Dots.

Brown adipose tissue (BAT) has been identified as a promising target for the treatment of obesity, diabetes, and relevant metabolism disorders because of the adaptive thermogenesis ability of this tissue. Visualizing BAT may provide an essential tool for pathology study, drug screening, and efficacy evaluation. Owing to limitations of current nuclear and magnetic resonance imaging approaches for BAT detection, fluorescence imaging has advantages in large-scale preclinical research on small animals. Here, fast BAT imaging in mice is conducted based on polymer dots as fluorescent probes. As early as 5 min after the intravenous injection of polymer dots, extensive fluorescence is detected in the interscapular BAT and axillar BAT. In addition, axillar and inguinal white adipose tissues (WAT) are recognized. The real-time in vivo behavior of polymer dots in rodents is monitored using the probe-based confocal laser endomicroscopy imaging, and the preferred accumulation in BAT over WAT is confirmed by histological assays. Moreover, the whole study is conducted without a low temperature or pharmaceutical stimulation. The imaging efficacy is verified at the cellular, histological, and whole-body levels, and the present results indicate that fluorescent polymer dots may be a promising tool for the visualization of BAT in living subjects.

Delineation of retroperitoneal metastatic lymph nodes in ovarian cancer with near-infrared fluorescence imaging.

Lymph node metastasis occurs in early-stage and late-stage ovarian cancers. Systematic lymphadenectomy is frequently conducted in an attempt to prevent disease progression. However, this method is associated with multiple complications. Therefore, it is necessary to develop a less invasive and more sensitive method for detecting lymphatic metastasis in ovarian cancer. The aim of the present study was to develop an appropriate fluorescent label for the analysis of lymphatic metastasis in vivo. To this end, epithelial ovarian cancer cells with high potential for lymph node metastasis were labeled using mCherry fluorescence. The cells were then imaged in vitro to determine the expression of mCherry, and in a mouse xenograft model in vivo. The data demonstrated the successful identification of metastatic retroperitoneal lymph nodes by co-localization with lymph nodes labeled by near-infrared fluorescence nanoparticles in vivo. These data provided important insights into the further development of methods for intra-operative identification of lymphatic metastasis and the mechanisms underlying lymphatic metastasis.

Facilely synthesized pH-responsive fluorescent polymer dots entrapping doped and coupled doxorubicin for nucleus-targeted chemotherapy.

Doxorubicin (Dox) functionalization methods can affect the Dox loading efficiency and release capability in nanosized drug delivery systems. Herein, different Dox-functionalized (doping, coupling, and doping and coupling) fluorescent poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PFBT) polymer dots were designed and their application performance was evaluated. Polyethylene glycol-modified doxorubicin (PEG-Dox) was synthesized using a responsive hydrazone linker. PEG-DOX-doped polymer dots were self-assembled using a co-precipitation method and free PEG-Dox was further coupled on the surface of the polymer dots via an EDC-NHS coupling to prepare the PEG-Dox doped and coupled PFBT polymer dots. The hydrazone linker of PEG-Dox is responsive to the acidic environment, resulting in the doped Dox being released into the cell nucleus and the coupled Dox changes the structure of the polymer dots and accelerates the release of the doped Dox. Moreover, the coupled Dox linked via an amide bond was still on the surface of the polymer dots and retained their cytoplasmic toxicity for a synergistic effect. A high Dox carrying efficiency (weight of the loaded Dox/weight of PFBT) was achieved using the PEG-Dox doped and coupled PFBT polymer dots: 107% and 82% of Dox was released in vitro within 24 h at pH 5.5. The cytotoxicity and cell imaging were investigated in three cancer cell lines: cervical cancer cells (HeLa), lung cancer cells (NCI-H292), and glioma cells (U87-MG); the results indicate that the PEG-Dox doped and coupled PFBT polymer dots show a distinct killing efficacy and nucleus targeted capability. Moreover, in vivo tumor suppression was observed in lung tumor-bearing mice over 20 days and no weight loss and damage or inflammation of the major organs were detected using the PEG-Dox doped and coupled PFBT polymer dots.