Dual-modality Imaging Probe Research Articles

Composite nanoparticle of Au and quantum dots for X-ray computed tomography and fluorescence dual-mode imaging in vivo

In this study, composite nanoparticles comprising Au nanoparticle and quantum dots were built and used for contrast-enhanced computed tomography imaging (CT) and fluorescence dual-mode imaging in vivo. The nanoparticle exhibited good monodispersity and good biocompatibility, and had excellent CT contrast-enhancement effect and fluorescence imaging capability. They were appropriate for being used as dual-mode imaging probe in vivo.

Development of a multimodal imaging probe by encapsulating iron oxide nanoparticles with functionalized amphiphiles for lymph node imaging.

We tried to develop a multimodal iron oxide nanoparticles (IO NP) imaging probe by an encapsulation method using specific amphiphiles for (68)Ga-labeling and lymph node-targeting. Nanoparticles (NPs) were encapsulated with a solution containing polysorbate 60 and the amphiphiles. The prepared NPs were labeled with (68)Ga and tested in vitro and in vivo. Prepared 1,4,7-triazacyclononane-1,4,7-triacetic acid-IO-Mannose (NOTA-IO-Man) showed a narrow size distribution, and no significant aggregation or degradation under harsh conditions. The relaxivity coefficient of (68)Ga-NOTA-IO-Man was higher than that of ferumoxide. The accumulation of (68)Ga-NOTA-IO-Man in the lymph node after injection into rat's footpad was confirmed by both positron emission tomography and MRI. We successfully developed PET/MRI dual-modality imaging probe targeting lymph nodes by using the facile encapsulation method.

Molecular platform for design and synthesis of targeted dual-modality imaging probes.

We report a versatile dendritic structure based platform for construction of targeted dual-modality imaging probes. The platform contains multiple copies of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) branching out from a 1,4,7-triazacyclononane-N,N′,N″-triacetic acid (NOTA) core. The specific coordination chemistries of the NOTA and DOTA moieties offer specific loading of 68/67Ga3+ and Gd3+, respectively, into a common molecular scaffold. The platform also contains three amino groups which can potentiate targeted dual-modality imaging of PET/MRI or SPECT/MRI (PET: positron emission tomography; SPECT: single photon emission computed tomography; MRI: magnetic resonance imaging) when further functionalized by targeting vectors of interest. To validate this design concept, a bimetallic complex was synthesized with six peripheral Gd-DOTA units and one Ga-NOTA core at the center, whose ion T1 relaxivity per gadolinium atom was measured to be 15.99 mM–1 s–1 at 20 MHz. Further, the bimetallic agent demonstrated its anticipated in vivo stability, tissue distribution, and pharmacokinetic profile when labeled with 67Ga. When conjugated with a model targeting peptide sequence, the trivalent construct was able to visualize tumors in a mouse xenograft model by both PET and MRI via a single dose injection.

Phenylboronic acid-modified magnetic nanoparticles as a platform for carbon dot conjugation and doxorubicin delivery.

We describe the preparation of phenylboronic acid-modified magnetofluorescent nanoparticles (NPs) consisting of MnFe2O4 magnetic NPs conjugated to fluorescent carbon dots (Cdots). These NPs are useful for both optical and magnetic resonance imaging (MRI) modalities and could also be used to deliver the water-insoluble chemotherapy drug, doxorubicin (Dox). In this study, hydrophobic MnFe2O4 NPs were transferred from organic media to water by coordinating with 4-carboxyphenylboronic acid ligands, which also act as a cancer cell-specific targeting ligand and a site for conjugation to fluorescent Cdots, allowing the preparation of phenylboronic acid-modified magnetofluorescent NPs. The NPs displayed colloidal stability at different pH values and salt concentrations, and exhibited negligible cytotoxicity against HeLa cancer cells with >85% cell viability at concentrations of up to 500 μg mL-1. Confocal laser scanning microscopy showed the specificity of the magnetofluorescent NPs in HeLa cells. MRI experiments showed that the magnetofluorescent NPs were effective contrast enhancement agents in T2-weighted MRI. Moreover, the NPs were also found to be effective fluorescent markers in an in vivo experiment in zebrafish embryos. Dox was attached to the NPs by π-π stacking interactions, and was delivered in a targeted manner. The results indicated that these magnetofluorescent NPs could deliver Dox efficiently and induce an anticancer effect in HeLa cells, as confirmed by confocal laser scanning microscopy and in vitro cytotoxicity assays.

Conjugation of multivalent ligands to gold nanoshells and designing a dual modality imaging probe.

Design and synthesis of branched tetraethylene glycol (TEG) based ligands for subsequent conjugation to gold nanoshells are reported. TEG enhances the aqueous solubility of hollow gold nanoshells (HAuNShs), and the branched architecture provides stability. An examination of the supernatant of the surface displacement reaction shows that the structure of the ligand plays an important role in the functionalization of HAuNShs. The binding of multivalent ligands leads to rupturing of the gold nanoshell architecture; most probably due to the large dendron not compensating the replacement of small citrate capping agents. The construction of a probe with dual imaging capabilities is demonstrated by covalent linking of a dendron containing Cy5.5A dye to gold nanoshells. It leads to fluorescence quenching of Cy5.5A by the gold nanoshells, as evidenced in solution and in cellular internalization studies with J774 and bEnd.3 cells.

A facile strategy to enable nanoparticles for simultaneous phase transfer, folate receptor targeting, and cisplatin delivery

Diagnostic and therapeutic strategies related to cancer treatment are being continually developed for enhancing the effectiveness of the treatment. Active targeting nanoparticles (NPs) with therapeutic capability are a major requirement of cancer therapeutics. Herein, we present a general one-pot approach for simultaneously (1) achieving the phase transfer of various NPs from an organic solvent to an aqueous phase, and (2) grafting an active targeting ligand (folate) via electrostatic interactions as well as a therapeutic agent (cisplatin) via coordinative interactions of platinum atoms with carboxylic acid ligands on the surface of the NPs. This approach allows rapid, simple, and versatile bioconjugation without the need for additional crosslinking reagents. Taking AgInS2/ZnS quantum dots (AQDs) as an example, we show that NPs can be tailored to possess both targeting activity and therapeutic capability. In this study, AQDs exhibited a dose-dependent antiproliferative effect on HeLa cancer cells, indicating the possibility of using the obtained AQDs as highly effective dual-modality imaging probes for simultaneous cancer diagnosis and chemotherapy. In addition, the proposed one-pot approach can be extended to various other NPs (e.g., quantum dots, metal oxides, and metallic and magnetic materials) that can be successfully conjugated with folate via hydrophobic interactions and electrostatic immobilization during ultrasonication. Bioconjugation of the NPs was investigated by dynamic light scattering, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy before and after the phase transfer.

Magneto-fluorescent core-shell supernanoparticles.

Magneto-fluorescent particles have been recognized as an emerging class of materials that exhibit great potential in advanced applications. However, synthesizing such magneto-fluorescent nanomaterials that simultaneously exhibit uniform and tunable sizes, high magnetic content loading, maximized fluorophore coverage at the surface, and a versatile surface functionality has proven challenging. Here we report a simple approach for co-assembling magnetic nanoparticles with fluorescent quantum dots to form colloidal magneto-fluorescent supernanoparticles. Importantly, these supernanoparticles exhibit a superstructure consisting of a close packed magnetic nanoparticle “core” which is fully surrounded by a “shell” of fluorescent quantum dots. A thin layer of silica-coating provides high colloidal stability and biocompatiblity and a versatile surface functionality. We demonstrate that after surface pegylation, these silica-coated magneto-fluorescent supernanoparticles can be magnetically manipulated inside living cells while being optically tracked. Moreover, our silica-coated magneto-fluorescent supernanoparticles can also serve as an in vivo multi-photon and magnetic resonance dual-modal imaging probe.

Bio-inspired development of a dual-mode nanoprobe for MRI and Raman imaging.

New generation dual-mode imaging probes for MRI and Raman imaging techniques are developed, inspired by the hyper intense contrast enhancing capability in T1 -weighted MRI and characteristic Raman signal of natural melanin. MDA-MB-231cells labeled with dual-mode imaging probe are successfully detected in both T1-weighted MRI and Raman imaging.

Facile synthesis of functional gadolinium-doped CdTe quantum dots for tumor-targeted fluorescence and magnetic resonance dual-modality imaging.

Magnetic quantum dots (MQDs) are an important class of agents for fluorescence (FL)/magnetic resonance (MR) dual-modal imaging due to their excellent optical and magnetic properties. However, functional MQDs prepared by a simple room-temperature route as FL/MR dual-modal imaging probes are lacking. Herein, we report the fabrication of Gd-doped CdTe quantum dots (Gd:CdTe QDs) as an agent for FL/MR dual-modality imaging. The as-designed QDs with an ultrasmall particle size are synthesized by a facile one-pot aqueous synthesis approach at room temperature. They emit strong fluorescence at 640 nm with a quantum yield of 37% in water, and they have a high longitudinal relaxation rate (r1) value of 3.27 mM-1 s-1. With the further conjugation of folic acid, the Gd:CdTe QDs can successfully label live HepG2 cells for targeted cellular imaging and present no evidence of cellular toxicity up to the concentration of 0.5 mg mL-1. They have been employed as a suitable contrast agent successfully for tumor-targeted FL/MR dual-modal imaging in a mouse model.

A functionalized heterobimetallic99mTc/Re complex as a potential dual-modality imaging probe: synthesis, photophysical properties, cytotoxicity and cellular imaging investigations

A novel bimodal fluorescent/radiolabelled probe based on a pyridyltriazole scaffold (known as pyta) is reported here. The final dual imaging agent combines carboxylate functionalization, for biomolecule conjugation, with two distinct metal chelating sites: a pyta-based tricarbonylrhenium moiety as a fluorescent probe and a (99m)Tc(CO3)(+) core through the tridentate chelating iminodiacetic acid (IDA) clamp as a SPECT reporter. The heterodinuclear (99m)Tc/Re complex , as well as its non-radioactive dirhenium analog , was prepared in six steps. The (99m)Tc/Re agent is water-soluble and stable against histidine challenge. Its structural characterization was achieved by HPLC comparison with the non-radioactive complex . Upon excitation in the MLCT band at 321 nm, the compound exhibits a bright green luminescence centered at 496 nm, with a quantum yield of 0.86% in Tris buffer, pH 7.4. Additionally, the influence of this compound on cell viability was tested on malignant cell lines (A549, HT29 and MCF-7 human lung, colon and breast carcinomas, respectively). Cell viability after 72 h incubation at 37 °C with 300 μmol of complex was >60% for all cell lines. Finally, cellular uptake studies of compound were performed by fluorescent microscopy, showing that the complex was clearly detected at the cellular level in A549 cells and to a lesser extent in HT29 cells. Taking into consideration the luminescent properties, the good radiochemical purity and the promising biological data (in vitro stability, non-toxicity, and cell tracking in two cell lines), the functionalized (99m)Tc/Re dinuclear compound can be considered a potential pre- and intraoperative diagnostic probe.

Lanthanide(III) complexes of rhodamine-DO3A conjugates as agents for dual-modal imaging.

Two novel dual-modal MRI/optical probes based on a rhodamine–DO3A conjugate have been prepared. The bis(aqua)gadolinium(III) complex Gd.L1 and mono(aqua)gadolinium(III) complex Gd.L2 behave as dual-modal imaging probes (r1 = 8.5 and 3.8 mM–1 s–1 for Gd.L1 and Gd.L2, respectively; λex = 560 nm and λem = 580 nm for both complexes). The rhodamine fragment is pH-sensitive, and upon lowering of the pH, an increase in fluorescence intensity is observed as the spirolactam ring opens to give the highly fluorescent form of the molecule. The ligands are bimodal when coordinated to Tb(III) ions, inducing fluorescence from both the lanthanide center and the rhodamine fluorophore, on two independent time frames. Confocal imaging experiments were carried out to establish the localization of Gd.L2 in HEK293 cells and primary mouse islet cells (∼70% insulin-containing β cells). Colocalization with MitoTracker Green demonstrated Gd.L2’s ability to distinguish between tumor and healthy cells, with compartmentalization believed to be in the mitochondria. Gd.L2 was also evaluated as an MRI probe for imaging of tumors in BALB/c nude mice bearing M21 xenografts. A 36.5% decrease in T1 within the tumor was observed 30 min post injection, showing that Gd.L2 is preferentially up taken in the tumor. Gd.L2 is the first small-molecule MR/fluorescent dual-modal imaging agent to display an off–on pH switch upon its preferential uptake within the more acidic microenvironment of tumor cells.

Novel cancer-targeting SPECT/NIRF dual-modality imaging probe 99mTc-PC-1007: Synthesis and biological evaluation

Synthesis, characterization, in vitro and in vivo biological evaluation of a heptamethine cyanine based dual-mode single-photon emission computed tomography (SPECT)/near infrared fluorescence (NIRF) imaging probe 99mTc-PC-1007 is described. 99mTc-PC-1007 exhibited preferential accumulation in human breast cancer MCF-7 cells. Cancer-specific SPECT/CT and NIRF imaging of 99mTc-PC-1007 was performed in a breast cancer xenograft model. The probe uptake ratio of tumor to control (spinal cord) was calculated to be 4.02±0.56 at 6h post injection (pi) and 8.50±1.41 at 20h pi (P<0.0001). Pharmacokinetic parameters such as blood clearance and organ distribution were assessed.

A dual-modal magnetic nanoparticle probe for preoperative and intraoperative mapping of sentinel lymph nodes by magnetic resonance and near infrared fluorescence imaging

The ability to reliably detect sentinel lymph nodes for sentinel lymph node biopsy and lymphadenectomy is important in clinical management of patients with metastatic cancers. However, the traditional sentinel lymph node mapping with visible dyes is limited by the penetration depth of light and fast clearance of the dyes. On the other hand, sentinel lymph node mapping with radionucleotide technique has intrinsically low spatial resolution and does not provide anatomic details in the sentinel lymph node mapping procedure. This work reports the development of a dual modality imaging probe with magnetic resonance and near infrared imaging capabilities for sentinel lymph node mapping using magnetic iron oxide nanoparticles (10 nm core size) conjugated with a near infrared molecule with emission at 830 nm. Accumulation of magnetic iron oxide nanoparticles in sentinel lymph nodes leads to strong T2 weighted magnetic resonance imaging contrast that can be potentially used for preoperative localization of sentinel lymph nodes, while conjugated near infrared molecules provide optical imaging tracking of lymph nodes with a high signal to background ratio. The new magnetic nanoparticle based dual imaging probe exhibits a significant longer lymph node retention time. Near infrared signals from nanoparticle conjugated near infrared dyes last up to 60 min in sentinel lymph node compared to that of 25 min for the free near infrared dyes in a mouse model. Furthermore, axillary lymph nodes, in addition to sentinel lymph nodes, can be also visualized with this probe, given its slow clearance and sufficient sensitivity. Therefore, this new dual modality imaging probe with the tissue penetration and sensitive detection of sentinel lymph nodes can be applied for preoperative survey of lymph nodes with magnetic resonance imaging and allows intraoperative sentinel lymph node mapping using near infrared optical devices.

Dual-modality imaging with 99mTc and fluorescent indocyanine green using surface-modified silica nanoparticles for biopsy of the sentinel lymph node: an animal study

BackgroundWe propose a new approach to facilitate sentinel node biopsy examination by multimodality imaging in which radioactive and near-infrared (NIR) fluorescent nanoparticles depict deeply situated sentinel nodes and fluorescent nodes with anatomical resolution in the surgical field. For this purpose, we developed polyamidoamine (PAMAM)-coated silica nanoparticles loaded with technetium-99m (99mTc) and indocyanine green (ICG).MethodsWe conducted animal studies to test the feasibility and utility of this dual-modality imaging probe. The mean diameter of the PAMAM-coated silica nanoparticles was 30 to 50 nm, as evaluated from the images of transmission electron microscopy and scanning electron microscopy. The combined labeling with 99mTc and ICG was verified by thin-layer chromatography before each experiment. A volume of 0.1 ml of the nanoparticle solution (7.4 MBq, except for one rat that was injected with 3.7 MBq, and 1 μg of an ICG derivative [ICG-sulfo-OSu]) was injected submucosally into the tongue of six male Wistar rats.ResultsScintigraphic images showed increased accumulation of 99mTc in the neck of four of the six rats. Nineteen lymph nodes were identified in the dissected neck of the six rats, and a contact radiographic study showed three nodes with a marked increase in uptake and three nodes with a weak uptake. NIR fluorescence imaging provided real-time clear fluorescent images of the lymph nodes in the neck with anatomical resolution. Six lymph nodes showed weak (+) to strong (+++) fluorescence, whereas other lymph nodes showed no fluorescence. Nodes showing increased radioactivity coincided with the fluorescent nodes. The radioactivity of 15 excised lymph nodes from the four rats was assayed using a gamma well counter. Comparisons of the levels of radioactivity revealed a large difference between the high-fluorescence-intensity group (four lymph nodes; mean, 0.109% ± 0.067%) and the low- or no-fluorescence-intensity group (11 lymph nodes; mean, 0.001% ± 0.000%, p < 0.05). Transmission electron microscopy revealed that small black granules were localized to and dispersed within the cytoplasm of macrophages in the lymph nodes.ConclusionAlthough further studies are needed to determine the appropriate dose of the dual-imaging nanoparticle probe for effective sensitivity and safety, the results of this animal study revealed a novel method for improved node detection by a dual-modality approach for sentinel lymph node biopsy.

Aptamer-functionalized, ultra-small, monodisperse silica nanoconjugates for targeted dual-modal imaging of lymph nodes with metastatic tumors.

A dual-modal imaging probe based on size-controlled silica nanoconjugates was synthesized for targeted imaging of lymph nodes by means of both PET and near infrared fluorescence techniques. 20 nm nanoconjugates (see scheme) functionalized with an aptamer (green triangles) that targets 4T1 breast cancer cells improved the detection efficiency of sentinel lymph nodes with metastatic tumors. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Multifunctional Fe3O4@C@Ag hybrid nanoparticles as dual modal imaging probes and near-infrared light-responsive drug delivery platform

Multifunctional nanocarriers based on Fe3O4@C@Ag hybrid nanoparticles with a diameter of 200 nm were fabricated by a facile method. Silver (Ag) nanoparticles were deposited onto the surface of Fe3O4@C nanospheres in dimethyl formamide (DMF) solution by reducing silver nitrate (AgNO3) with glucose. The nanocarriers of doxorubicin (DOX) with a high loading content of 997 mg/g and near-infrared (NIR) light-responsive drug delivery based on Ag nanoparticles were realized. Strong fluorescence can be observed in cell nucleus due to the presence of DOX after irradiated by NIR, and most cells were in the state of apoptosis, which indicates NIR-regulated drug release was realized. Moreover, measurements show that the nanocarriers could also be used as magnetic resonance imaging (MRI) contrast agents and fluorescent probes. The combination of synergistic NIR controlled drug release and dual modal imaging of MRI and two-photon fluorescence (TPF) imaging could lead to a potential multifunctional system for biomedical diagnosis and therapy.

Water soluble fluorescent-magnetic perylenediimide-containing maghemite-nanoparticles for bimodal MRI/OI imaging

The protein shell of apoferritin-encapsulated maghemite nanoparticles was functionalized with two different red-emitting perylenediimide fluorophores (PDI). One glycosacharide-PDI complex has been synthesized for the first time to be labeled to apoferritin-encapsulated maghemite nanoparticles. Bifunctionality of maghemite@perylenediimide was demonstrated by both magnetic-core and fluorescent-labeled shell properties. SQUID measurements confirmed superparamagnetic behavior above 35K. Fluorescence of perylenediimides is retained once attached to the magnetic nanoparticle. Moreover, fluorescence microscopy showed that one of these fluorescent-magnetic nanoparticles was specifically internalized in bifidobacteria without affecting cell viability. These results revealed that the dual-modal imaging probes of maghemite@perylenediimide nanoparticles have the potential to be used as optical/MR dual imaging agents.

Au/SiO2/QD core/shell/shell nanostructures with plasmonic-enhanced photoluminescence

A sol–gel method has been developed to fabricate Au/SiO2/quantum dot (QD) core–shell–shell nanostructures with plasmonic-enhanced photoluminescence (PL). Au nanoparticle (NP) was homogeneously coated with a SiO2 shell with adjusted thickness through a Stober synthesis. When the toluene solution of hydrophobic CdSe/ZnS QDs was mixed with partially hydrolyzed 3-aminopropyltrimethoxysilane (APS) sol, the ligands on the QDs were replaced by a thin functional SiO2 layer because the amino group in partially hydrolyzed APS has strong binding interaction with the QDs. Partially hydrolyzed APS plays an important role as a thin functional layer for the transfers of QDs to water phase and the subsequent connection to aqueous SiO2-coated Au NPs. Although Au NPs were demonstrated as efficient PL quenchers when the SiO2 shell on the Au NPs is thin (less than 5 nm), we found that precise control of the spacing between the Au NP core and the QD shell resulted in QDs with an enhancement of 30 % of PL efficiency. The Au/SiO2/QD core/shell/shell nanostructures also reveal strong surface plasmon scattering, which makes the Au/SiO/QD core–shell–shell nanostructures an excellent dual-modality imaging probe. This technology can serve as a general route for encapsulating a variety of discrete nanomaterials because monodispersed nanostructures often have a similar surface chemistry.

Efficient Construction of PET/Fluorescence Probe Based on Sarcophagine Cage: An Opportunity to Integrate Diagnosis with Treatment

Due to the shortage of established platforms/methods for multimodality probe construction, in this study, we developed a heterofunctional chelator, BaAn(Boc)Sar, from sarcophagine cage as a general platform for dual-modality probe construction. A dual-modality probe for positron-emission tomography (PET) and fluorescence imaging was synthesized using the developed BaAn(Boc)Sar chelator. The c(RGDyK)(2) peptide (denoted as RGD(2)) and fluorescence dye Cy5.5 were conjugated with BaAn(Boc)Sar to form BaAnSar-RGD(2)-Cy5.5. Then, BaAnSar-RGD(2)-Cy5.5 was labeled with (64)Cu in ammonium acetate buffer. PET and fluorescent imaging were carried out to evaluate (64)Cu-BaAnSar-RGD(2)-Cy5.5 in nude mice bearing U87MG glioblastoma xenograft. The BaAnSar-RGD(2)-Cy5.5 was labeled with (64)Cu very efficiently in 0.1 M NH(4)OAc buffer within 10 min at 37 °C in the yield of 86.7 ± 4.4 % (n = 3). The specific activity of (64)Cu-BaBaSar-RGD(2) was controlled at 50-200 mCi/μmol for the consideration of both PET and optical imaging. MicroPET quantification analysis shows that the U87MG tumor uptake is 6.41 ± 0.28, 6.51 ± 1.45, and 5.92 ± 1.57 %ID/g at 1, 4, and 20 h postinjection, respectively. Good correlation was obtained between the tumor to muscle ratios measured by the radioactivity and fluorescence intensity. As a proof of concept, an animal surgery study demonstrated that this dual-modality probe would greatly benefit the patients because the PET moiety could be used for tumor detection, and the fluorescent moiety would allow image-guided surgery. Our findings demonstrated the effectiveness and feasibility of preparing dual-modality imaging probes based on the sarcophagine scaffold. The resulting PET and fluorescent imaging probe also holds a great potential for clinical translation.

Mesoporous silica-coated gold nanorods with embedded indocyanine green for dual mode X-ray CT and NIR fluorescence imaging

Indocyanine green-loaded mesoporous silica-coated gold nanorods (ICG-loaded Au@SiO2) were prepared for the dual capability of X-ray computed tomography (CT) and fluorescence imaging. X-ray CT scanning showed that ICG-loaded Au@SiO2 could provide significant contrast enhancement; Near-infrared fluorescence generated by the nanomaterial was present up to 12 h post intratumoral injection, thus enabling ICG-loaded Au@SiO2 to be used as a promising dual mode imaging contrast agent. Multiplexed images can be more easily obtained with this novel type of multimodal nanostructure compared with traditional contrast agents. The dual mode imaging probe has great potential for use in applications such as cancer targeting, molecular imaging in combination with radiotherapy, and photothermolysis.