Vivo Fluorescence Imaging Research Articles

Preparation and evaluation of amoxicillin loaded dual molecularly imprinted nanoparticles for anti-Helicobacter pylori therapy

This paper reports studies on preparation and evaluation of amoxicillin loaded dual molecularly imprinted nanoparticles (Amo/Dual-MIPs) designed for anti-H. pylori therapy. Both MNQA and AmoNa were chosen as templates to prepare Dual-MIPs using inverse microemulsion polymerization method. NQA was modified with myristic acid (MNQA) to become amphiphilic and assist in leaving NQA cavities on the surface of Dual-MIPs for H. pylori adhesion. AmoNa was applied to produce imprinting sites in Dual-MIPs for rebinding AmoNa to exert its anti-H. pylori effect. Batch rebinding test demonstrated a preferential rebinding effect of NQA toward the Dual-MIPs. In vivofluorescence imaging showed the prolonged residence time of Dual-MIPs in H. pylori infected mice stomachs after intragastric administration of nanoparticles.In vivo H. pylori clearance tests indicated Amo/Dual-MIPs had a better aniti-H. pylori effect than amoxicillin powder did. In conclusion, Amo/Dual-MIPs may provide an alternative drug delivery strategy for anti-H. pylori therapy.

Fluorescence Imaging In Vivo at Wavelengths beyond 1500 nm

AbstractCompared to imaging in the visible and near‐infrared regions below 900 nm, imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) is a promising method for deep‐tissue high‐resolution optical imaging in vivo mainly owing to the reduced scattering of photons traversing through biological tissues. Herein, semiconducting single‐walled carbon nanotubes with large diameters were used for in vivo fluorescence imaging in the long‐wavelength NIR region (1500–1700 nm, NIR‐IIb). With this imaging agent, 3–4 μm wide capillary blood vessels at a depth of about 3 mm could be resolved. Meanwhile, the blood‐flow speeds in multiple individual vessels could be mapped simultaneously. Furthermore, NIR‐IIb tumor imaging of a live mouse was explored. NIR‐IIb imaging can be generalized to a wide range of fluorophores emitting at up to 1700 nm for high‐performance in vivo optical imaging.

Fluorescence Imaging In Vivo at Wavelengths beyond 1500 nm.

Compared to imaging in the visible and near-infrared regions below 900 nm, imaging in the second near-infrared window (NIR-II, 1000-1700 nm) is a promising method for deep-tissue high-resolution optical imaging in vivo mainly owing to the reduced scattering of photons traversing through biological tissues. Herein, semiconducting single-walled carbon nanotubes with large diameters were used for in vivo fluorescence imaging in the long-wavelength NIR region (1500-1700 nm, NIR-IIb). With this imaging agent, 3-4 μm wide capillary blood vessels at a depth of about 3 mm could be resolved. Meanwhile, the blood-flow speeds in multiple individual vessels could be mapped simultaneously. Furthermore, NIR-IIb tumor imaging of a live mouse was explored. NIR-IIb imaging can be generalized to a wide range of fluorophores emitting at up to 1700 nm for high-performance in vivo optical imaging.

Cancer Therapy: Nucleus‐Targeting Gold Nanoclusters for Simultaneous In Vivo Fluorescence Imaging, Gene Delivery, and NIR‐Light Activated Photodynamic Therapy (Adv. Funct. Mater. 37/2015)

Nucleus-targeting gold nanoclusters (TAT peptide-Au NCs) can act as intrinsic fluorescence probe for bioimaging, as shown by K. C. Hwang and co-workers on page 5934. The nanoclusters also sensitize formation of singlet oxygen upon NIR light activation, to exert effective photodynamic therapeutic effects in killing cancer cells via subsequent DNA damage inside the nucleus, without using any additional photosensitizers.

Nucleus‐Targeting Gold Nanoclusters for Simultaneous In Vivo Fluorescence Imaging, Gene Delivery, and NIR‐Light Activated Photodynamic Therapy

The nucleus is one of the most important cellular organelles and molecular anticancer drugs, such as cisplatin and doxorubicin, that target DNA inside the nucleus, are proving to be more effective at killing cancer cells than those targeting at cytoplasm. Nucleus‐targeting nanomaterials are very rare. It is a grand challenge to design highly efficient nucleus‐targeting multifunctional nanomaterials that are able to perform simultaneous bioimaging and therapy for the destruction of cancer cells. Here, unique nucleus‐targeting gold nanoclusters (TAT peptide–Au NCs) are designed to perform simultaneous in vitro and in vivo fluorescence imaging, gene delivery, and near‐infrared (NIR) light activated photodynamic therapy for effective cancer cell killing. Confocal laser scanning microscopy observations reveal that TAT peptide–Au NCs are distributed throughout the cytoplasm region with a significant fraction entering into the nucleus. The TAT peptide–Au NCs can also act as DNA nanocargoes to achieve very high gene transfection efficiencies (≈81%) in HeLa cells and in zebrafish. Furthermore, TAT peptide–Au NCs are also able to sensitize formation of singlet oxygen (1O2) without the co‐presence of organic photosensitizers for the destruction of cancer cells upon NIR light photoexcitation.

Near-Infrared Squaraine Dye Encapsulated Micelles for in Vivo Fluorescence and Photoacoustic Bimodal Imaging.

Combined near-infrared (NIR) fluorescence and photoacoustic imaging techniques present promising capabilities for noninvasive visualization of biological structures. Development of bimodal noninvasive optical imaging approaches by combining NIR fluorescence and photoacoustic tomography demands suitable NIR-active exogenous contrast agents. If the aggregation and photobleaching are prevented, squaraine dyes are ideal candidates for fluorescence and photoacoustic imaging. Herein, we report rational selection, preparation, and micelle encapsulation of an NIR-absorbing squaraine dye (D1) for in vivo fluorescence and photoacoustic bimodal imaging. D1 was encapsulated inside micelles constructed from a biocompatible nonionic surfactant (Pluoronic F-127) to obtain D1-encapsulated micelles (D1(micelle)) in aqueous conditions. The micelle encapsulation retains both the photophysical features and chemical stability of D1. D1(micelle) exhibits high photostability and low cytotoxicity in biological conditions. Unique properties of D1(micelle) in the NIR window of 800-900 nm enable the development of a squaraine-based exogenous contrast agent for fluorescence and photoacoustic bimodal imaging above 820 nm. In vivo imaging using D1(micelle), as demonstrated by fluorescence and photoacoustic tomography experiments in live mice, shows contrast-enhanced deep tissue imaging capability. The usage of D1(micelle) proven by preclinical experiments in rodents reveals its excellent applicability for NIR fluorescence and photoacoustic bimodal imaging.

Tracking GFP-labeled Transplanted Mouse MSC in Nude Mice Using in Vivo Fluorescence Imaging

Tracking GFP-labeled Transplanted Mouse MSC in Nude Mice Using in Vivo Fluorescence Imaging

In vivo fluorescence imaging of β-amyloid plaques with push-pull dimethylaminothiophene derivatives.

In vivo fluorescence imaging of β-amyloid (Aβ) plaques in the brain is expected to be used as a new method for detecting Alzheimer's disease (AD). We synthesized novel push-pull dimethylaminothiophenyl (DTM) derivatives and evaluated their utility as in vivo fluorescence imaging probes targeting Aβ plaques. As a result, we found that DTM-2 is a promising fluorescent probe for Aβ plaques in the AD brains.

In vivo fluorescence imaging and urinary monoamines as surrogate biomarkers of disease progression in a mouse model of pheochromocytoma.

Pheochromocytoma (PHEO) is a rare but potentially lethal neuroendocrine tumor arising from catecholamine-producing chromaffin cells. Especially for metastatic PHEO, the availability of animal models is essential for developing novel therapies. For evaluating therapeutic outcome in rodent PHEO models, reliable quantification of multiple organ lesions depends on dedicated small-animal in vivo imaging, which is still challenging and only available at specialized research facilities. Here, we investigated whether whole-body fluorescence imaging and monitoring of urinary free monoamines provide suitable parameters for measuring tumor progression in a murine allograft model of PHEO. We generated an mCherry-expressing mouse PHEO cell line by lentiviral gene transfer. These cells were injected subcutaneously into nude mice to perform whole-body fluorescence imaging of tumor development. Urinary free monoamines were measured by liquid chromatography with tandem mass spectrometry. Tumor fluorescence intensity and urinary outputs of monoamines showed tumor growth-dependent increases (P < .001) over the 30 days of monitoring post-tumor engraftment. Concomitantly, systolic blood pressure was increased significantly during tumor growth. Tumor volume correlated significantly (P < .001) and strongly with tumor fluorescence intensity (rs = 0.946), and urinary outputs of dopamine (rs = 0.952), methoxytyramine (rs = 0.947), norepinephrine (rs = 0.756), and normetanephrine (rs = 0.949). Dopamine and methoxytyramine outputs allowed for detection of lesions at diameters below 2.3 mm. Our results demonstrate that mouse pheochromocytoma (MPC)-mCherry cell tumors are functionally similar to human PHEO. Both tumor fluorescence intensity and urinary outputs of free monoamines provide precise parameters of tumor progression in this sc mouse model of PHEO. This animal model will allow for testing new treatment strategies for chromaffin cell tumors.

Cerebral Arterial Pulsation Drives Paravascular CSF–Interstitial Fluid Exchange in the Murine Brain

CSF from the subarachnoid space moves rapidly into the brain along paravascular routes surrounding penetrating cerebral arteries, exchanging with brain interstitial fluid (ISF) and facilitating the clearance of interstitial solutes, such as amyloid β, in a pathway that we have termed the "glymphatic" system. Prior reports have suggested that paravascular bulk flow of CSF or ISF may be driven by arterial pulsation. However, cerebral arterial pulsation could not be directly assessed. In the present study, we use in vivo two-photon microscopy in mice to visualize vascular wall pulsatility in penetrating intracortical arteries. We observed that unilateral ligation of the internal carotid artery significantly reduced arterial pulsatility by ~50%, while systemic administration of the adrenergic agonist dobutamine increased pulsatility of penetrating arteries by ~60%. When paravascular CSF-ISF exchange was evaluated in real time using in vivo two-photon and ex vivo fluorescence imaging, we observed that internal carotid artery ligation slowed the rate of paravascular CSF-ISF exchange, while dobutamine increased the rate of paravascular CSF-ISF exchange. These findings demonstrate that cerebral arterial pulsatility is a key driver of paravascular CSF influx into and through the brain parenchyma, and suggest that changes in arterial pulsatility may contribute to accumulation and deposition of toxic solutes, including amyloid β, in the aging brain.

Design and Synthesis of Curcumin Analogues for in Vivo Fluorescence Imaging and Inhibiting Copper-Induced Cross-Linking of Amyloid Beta Species in Alzheimer’s Disease

In this article, we first designed and synthesized curcumin-based near-infrared (NIR) fluorescence imaging probes for detecting both soluble and insoluble amyloid beta (Aβ) species and then an inhibitor that could attenuate cross-linking of Aβ induced by copper. According to our previous results and the possible structural stereohindrance compatibility of the Aβ peptide and the hydrophobic/hydrophilic property of the Aβ13-20 (HHQKLVFF) fragment, NIR imaging probe CRANAD-58 was designed and synthesized. As expected CRANAD-58 showed significant fluorescence property changes upon mixing with both soluble and insoluble Aβ species in vitro. In vivo NIR imaging revealed that CRANAD-58 was capable of differentiating transgenic and wild-type mice as young as 4 months old, the age that lacks apparently visible Aβ plaques and Aβ is likely in its soluble forms. According to our limited studies on the interaction mechanism between CRANAD-58 and Aβ, we also designed CRANAD-17 to attenuate the cross-linking of Aβ42 induced by copper. It is well-known that the coordination of copper with imidazoles on Histidine-13 and 14 (H13, H14) of Aβ peptides could initialize covalent cross-linking of Aβ. In CRANAD-17, a curcumin scaffold was used as an anchoring moiety to usher the designed compound to the vicinity of H13 and H14 of Aβ, and imidazole rings were incorporated to compete with H13/H14 for copper binding. The results of SDS-PAGE gel and Western blot indicated that CRANAD-17 was capable of inhibiting Aβ42 cross-linking induced by copper. This raises a potential for CRANAD-17 to be considered for AD therapy.

In Vivo Fluorescence Imaging of IgG1 Aggregates After Subcutaneous and Intravenous Injection in Mice

To monitor the biodistribution of IgG1 aggregates upon subcutaneous (SC) and intravenous (IV) administration in mice and measure their propensity to stimulate an early immune response. A human mAb (IgG1) was fluorescently labeled, aggregated by agitation stress and injected in SKH1 mice through SC and IV routes. The biodistribution of monomeric and aggregated formulations was monitored over 47days by fluorescence imaging and the early immune response was measured by quantifying the level of relevant cytokines in serum using a Bio-plex assay. The aggregates remained at the SC injection site for a longer time than monomers but after entry into the systemic circulation disappeared faster than monomers. Upon IV administration, both monomers and aggregates spread rapidly throughout the circulation, and a strong accumulation in the liver was observed for both species. Subsequent removal from the circulation was faster for aggregates than monomers. No accumulation in lymph nodes was observed after SC or IV administration. Administration of monomers and aggregates induced similar cytokine levels, but SC injection resulted in higher cytokine levels than IV administration. These results show differences in biodistribution and residence time between IgG1 aggregates and monomers. The long residence time of aggregates at the SC injection site, in conjunction with elevated cytokine levels, may contribute to an enhanced immunogenicity risk of SC injected aggregates compared to that of monomers.

In Vivo Fluorescence Imaging Reveals the Promotion of Mammary Tumorigenesis by Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) are multipotent adult stem cells which are recruited to the tumor microenvironment (TME) and influence tumor progression through multiple mechanisms. In this study, we examined the effects of MSCs on the tunmorigenic capacity of 4T1 murine mammary cancer cells. It was found that MSC-conditioned medium increased the proliferation, migration, and efficiency of mammosphere formation of 4T1 cells in vitro. When co-injected with MSCs into the mouse mammary fat pad, 4T1 cells showed enhanced tumor growth and generated increased spontaneous lung metastasis. Using in vivo fluorescence color-coded imaging, the interaction between GFP-expressing MSCs and RFP-expressing 4T1 cells was monitored. As few as five 4T1 cells could give rise to tumor formation when co-injected with MSCs into the mouse mammary fat pad, but no tumor was formed when five or ten 4T1 cells were implanted alone. The elevation of tumorigenic potential was further supported by gene expression analysis, which showed that when 4T1 cells were in contact with MSCs, several oncogenes, cancer markers, and tumor promoters were upregulated. Moreover, in vivo longitudinal fluorescence imaging of tumorigenesis revealed that MSCs created a vascularized environment which enhances the ability of 4T1 cells to colonize and proliferate. In conclusion, this study demonstrates that the promotion of mammary cancer progression by MSCs was achieved through the generation of a cancer-enhancing microenvironment to increase tumorigenic potential. These findings also suggest the potential risk of enhancing tumor progression in clinical cell therapy using MSCs. Attention has to be paid to patients with high risk of breast cancer when considering cell therapy with MSCs.

Effect of Cerium Oxide Nanoparticles on Rice: A Study Involving the Antioxidant Defense System and In Vivo Fluorescence Imaging

Previous studies have reported the uptake of cerium oxide nanoparticles (nCeO2) by plants, but their physiological impacts are not yet well understood. This research was aimed to study the impact of nCeO2 on the oxidative stress and antioxidant defense system in germinating rice seeds. The seeds were germinated for 10 days in nCeO2 suspension at 62.5, 125, 250, and 500 mg L(-1) concentrations. The Ce uptake, growth performance, stress levels, membrane damage, and antioxidant responses in seedlings were analyzed. Ce in tissues increased with increased nCeO2 concentrations, but the seedlings showed no visible signs of toxicity. Biochemical assays and in vivo imaging of H2O2 revealed that, relative to the control, the 62.5 and 125 mg nCeO2 L(-1) treatments significantly reduced the H2O2 generation in both shoots and roots. Enhanced electrolyte leakage and lipid peroxidation were found in the shoots of seedlings grown at 500 mg nCeO2 L(-1). Altered enzyme activities and levels of ascorbate and free thiols resulting in enhanced membrane damage and photosynthetic stress in the shoots were observed at 500 mg nCeO2 L(-1). These findings demonstrate a nCeO2 concentration-dependent modification of oxidative stress and antioxidant defense system in rice seedlings.

Glycosyl‐Modified Diporphyrins for in Vitro and in Vivo Fluorescence Imaging

The application of probes for optical imaging is becoming popular as they have high safety and good biocompatibility. We prepared two kinds of glycosyl-modified diporphyrins, and their potentials as fluorescent probes were tested for the first time. After preparation of the glycosyl-modified porphyrin monomers, Ag-promoted coupling of the monomers was used to obtain glucose-modified porphyrin dimer (GPD) and lactose-modified porphyrin dimer (LPD). The strong interaction between the two porphyrin rings achieves red-shifted emission, and thus circumvents autofluorescence and light-scattering in biological samples. Although the glycosylation improves solubility, it also yielded selective attachment to cell membranes, and to chorions of early developmental-stage zebrafish. Patch-clamp experiments revealed the biocompatibility and low toxicity of GPD and LPD. Moreover, an in vivo imaging experiment provided direct evidence that zebrafish chorion contains sugar-binding proteins. The modification and derivatization make porphyrins potential bioimaging probes for specific optical imaging.

Role of CTR4 in the Virulence of Cryptococcus neoformans

ABSTRACTWhile research has identified an important contribution for metals, such as iron, in microbial pathogenesis, the roles of other transition metals, such as copper, remain mostly unknown. Recent evidence points to a requirement for copper homeostasis in the virulence of Cryptococcus neoformans based on a role for a CUF1 copper regulatory factor in mouse models and in a human patient cohort. C. neoformans is an important fungal pathogen that results in an estimated 600,000 AIDS-related deaths yearly. In the present studies, we found that a C. neoformans mutant lacking the CUF1-dependent copper transporter, CTR4, grows normally in rich medium at 37°C but has reduced survival in macrophages and attenuated virulence in a mouse model. This reduced survival and virulence were traced to a growth defect under nutrient-restricted conditions. Expression studies using a full-length CTR4-fluorescent fusion reporter construct demonstrated robust expression in macrophages, brain, and lung, the latter shown by ex vivo fluorescent imaging. Inductively coupled mass spectroscopy (ICP-MS) was used to probe the copper quota of fungal cells grown in defined medium and recovered from brain, which suggested a role for a copper-protective function of CTR4 in combination with cell metallothioneins under copper-replete conditions. In summary, these data suggest a role for CTR4 in copper-related homeostasis and subsequently in fungal virulence.

In Vivo Fluorescence Imaging with Ag2S Quantum Dots in the Second Near‐Infrared Region

Auf den Quantenpunkt gebracht: Ag2S-Quantenpunkte mit heller NIR-Fluoreszenz und einer Oberflächenbeschichtung aus verzweigtem PEG (siehe Schema) wurden für die Bildgebung in lebenden Kleintieren synthetisiert. Dank ihrer langen Zirkulationsdauer (ca. 4 h) wurden die QDs von Tumoren mit ungefähr 10 % der injizierten Dosis pro Gramm aufgenommen. Mäuse schieden die injizierten QDs hauptsächlich über den biliären Weg aus.

In Vivo Fluorescence Imaging with Ag2S Quantum Dots in the Second Near‐Infrared Region

Hits the dot: Ag(2)S quantum dots (QDs) with bright near-infrared-II fluorescence emission (around 1200 nm) and six-arm branched PEG surface coating were synthesized for in vivo small-animal imaging. The 6PEG-Ag(2)S QDs afforded a tumor uptake of approximately 10 % injected dose/gram, owing to a long circulation half-life of approximately 4 h. Clearance of the injected 6PEG-Ag(2)S QDs occurs mainly through the biliary pathway in mice.

In Vivo Fluorescence Imaging in the Second Near-Infrared Window with Long Circulating Carbon Nanotubes Capable of Ultrahigh Tumor Uptake

Cancer imaging requires selective high accumulation of contrast agents in the tumor region and correspondingly low uptake in healthy tissues. Here, by making use of a novel synthetic polymer to solubilize single-walled carbon nanotubes (SWNTs), we prepared a well-functionalized SWNT formulation with long blood circulation (half-life of ∼30 h) in vivo to achieve ultrahigh accumulation of ∼30% injected dose (ID)/g in 4T1 murine breast tumors in Balb/c mice. Functionalization dependent blood circulation and tumor uptake were investigated through comparisons with phospholipid-PEG solubilized SWNTs. For the first time, we performed video-rate imaging of tumors based on the intrinsic fluorescence of SWNTs in the second near-infrared (NIR-II, 1.1-1.4 μm) window. We carried out dynamic contrast imaging through principal component analysis (PCA) to immediately pinpoint the tumor within ∼20 s after injection. Imaging over time revealed increasing tumor contrast up to 72 h after injection, allowing for its unambiguous identification. The 3D reconstruction of the SWNTs distribution based on their stable photoluminescence inside the tumor revealed a high degree of colocalization of SWNTs and blood vessels, suggesting enhanced permeability and retention (EPR) effect as the main cause of high passive tumor uptake of the nanotubes.

In Vivo Fluorescence Imaging of Bone-Resorbing Osteoclasts

Osteoclasts are giant polykaryons responsible for bone resorption. Because an enhancement or loss of osteoclast function leads to bone diseases such as osteoporosis and osteopetrosis, real-time imaging of osteoclast activity in vivo can be of great help for the evaluation of drugs. Herein, pH-activatable chemical probes BAp-M and BAp-E have been developed for the detection of bone-resorbing osteoclasts in vivo. Their acid dissociation constants (pK(a)) were determined as 4.5 and 6.2 by fluorometry in various pH solutions. These pK(a) values should be appropriate to perform selective imaging of bone-resorbing osteoclasts, because synthesized probes cannot fluoresce intrinsically at physiological pH and the pH in the resorption pit is lowered to about 4.5. Furthermore, BAp-M and BAp-E have a bisphosphonate moiety that enabled the probes to localize on bone tissues. The hydroxyapatite (HA) binding assay in vitro was, therefore, performed to confirm the tight binding of the probes to the bone tissues. Our probes showed intense fluorescence at low pH values but no fluorescence signal under physiological pH conditions on HA. Finally, we applied the probes to in vivo imaging of osteoclasts by using intravital two-photon microscopy. As expected, the fluorescence signals of the probes were locally observed between the osteoclasts and bone tissues, that is, in resorption pits. These results indicate that our pH-activatable probes will prove to be a powerful tool for the selective detection of bone-resorbing osteoclasts in vivo, because this is the first instance where in vivo imaging has been conducted in a low-pH region created by bone-resorbing osteoclasts.