Multifunctional Magnetic Gd(3+) -Based Coordination Polymer Nanoparticles: Combination of Magnetic Resonance and Multispectral Optoacoustic Detections for Tumor-Targeted Imaging in vivo

α-Fe2O3@Au-PEG-Ce6-Gd Nanoparticles as Acidic H2O2-Driven Oxygenators for Multimodal Imaging and Synergistic Tumor Therapy

Nanoparticles with visual imaging capabilities and synergistic therapeutics have a bright future in antitumor applications. However, most of the current nanomaterials lack multiple imaging-guided therapeutic capabilities. In this study, a novel enhanced photothermal photodynamic antitumor nanoplatform with photothermal imaging, fluorescence (FL) imaging, and MRI-guided therapeutic capabilities was constructed by grafting gold, dihydroporphyrin Ce6, and Gd onto α-iron trioxide. This antitumor nanoplatform can convert NIR light into local hyperthermia at a temperature of up to 53 °C under NIR light irradiation, while Ce6 can generate singlet oxygen, which further synergizes the tumor-killing effect. At the same time, α-Fe₂O₃@Au-PEG-Ce6-Gd can also have significant photothermal imaging effect under light irradiation, which can guide to see the temperature change near the tumor tissue. It is worth noting that α-Fe₂O₃@Au-PEG-Ce6-Gd can have obvious MRI and FL imaging effects after tail vein injection in mice with blood circulation, realizing imaging-guided synergistic antitumor therapy. α-Fe₂O₃@Au-PEG-Ce6-Gd NPs provide a new solution for tumor imaging and treatment.

Nanoscale coordination polymers enabling antioxidants inhibition for enhanced chemodynamic therapy

Reactive oxygen species (ROS) generation to induce cell death is an effective strategy for cancer therapy. In particular, chemodynamic therapy (CDT), using Fenton-type reactions to generate highly cytotoxic hydroxyl radical (•OH), is a promising treatment modality. However, the therapeutic efficacy of ROS-based cancer treatment is still limited by some critical challenges, such as overexpression of enzymatic and non-enzymatic antioxidants by tumor cells, as well as the low tumor targeting efficiency of therapeutic agents. To address those problems, biomimetic CuZn protoporphyrin IX nanoscale coordination polymers have been developed, which significantly amplify oxidative stress against tumors by simultaneously inhibiting enzymatic and non-enzymatic antioxidants and initiating the CDT. In this design, cancer cell membrane camouflaged nanoparticle exhibits an excellent homotypic targeting effect. After being endocytosed into tumor cells, the nanoparticles induce depletion of the main non-enzymatic antioxidant glutathione (GSH) by undergoing a redox reaction with GSH. Afterward, the redox reaction generated cuprous ion (Cu⁺) works as a CDT agent for •OH generation. Furthermore, the released Zn protoporphyrin IX strongly inhibits the activity of the typical enzymatic antioxidant heme oxygenase-1. This tetra-modal synergistic strategy endows the biomimetic nanoparticles with great capability for anticancer therapy, which has been demonstrated in both in vitro and in vivo studies.

Synergistic Effect of Oxygen- and Nitrogen-Containing Groups in Graphene Quantum Dots: Red Emitted Dual-Mode Magnetic Resonance Imaging Contrast Agents with High Relaxivity

Contrast agents (CAs) in magnetic resonance imaging generally involve the dissociative Gd³⁺. Because of the limited ligancy of Gd³⁺, the balance between Gd³⁺ coordination stability (reducing the concentration of dissociative Gd³⁺) and increases in the number of coordination water molecules (enhancing the relaxivity) becomes crucial. Herein, the key factor of the synergistic effect between the O- and N-containing groups of graphene quantum dots for the structural design of CAs with both high relaxivity and low toxicity was obtained. The nitrogen-doped graphene quantum dots (NGQDs) with an O/N ratio of 0.4 were selected to construct high-relaxivity magnetic resonance imaging (MRI)-fluorescence dual-mode CAs. The coordination stability of Gd³⁺ can be increased through the synergetic coordination of O- and N-containing groups. The synergetic coordination of O- and N-containing groups can result in the short residency time of the water ligand and achieve high relaxivity. The resulting CAs (called NGQDs-Gd) exhibit a high relaxivity of 32.04 mM^-1 s^-1 at 114 μT. Meanwhile, the NGQDs-Gd also emit red fluorescence (614 nm), which can enable the MRI-fluorescence dual-mode imaging as the CAs. Moreover, the bio-toxicity and tumor-targeting behavior of NGQDs-Gd were also evaluated, and NGQDs-Gd show potential in MRI-fluorescence imaging in vivo.

Insights on Luminescent Micro- and Nanospheres of Infinite Coordination Polymers

Coordination polymers have been extensively studied in recent years. Some of these materials can exhibit several properties such as permanent porosity, high surface area, thermostability and light emission, as well as open sites for chemical functionalization. Concerning the fact that this kind of compounds are usually solids, the size and morphology of the particles are important parameters when an application is desired. Inside this context, there is a subclass of coordination polymers, named infinite coordination polymers (ICPs), which auto-organize as micro- or nanoparticles with low crystallinity. Specifically, the particles exhibiting spherical shapes and reduced sizes can be better dispersed, enter cells much easier than bulk crystals and be converted to inorganic materials by topotactic transformation. Luminescent ICPs, in particular, can find applications in several areas, such as sensing probes, light-emitting devices and bioimaging. In this review, we present the state-of-the-art of ICP-based spherical particles, including the growth mechanisms, some applications for luminescent ICPs and the challenges to overcome in future commercial usage of these materials.

Aptamer-mediated synthesis of multifunctional nano-hydroxyapatite for active tumour bioimaging and treatment

OBJECTIVES

The nano-hydroxyapatite (nHAp) is widely used to develop imaging probes and drug carriers due to its excellent bioactivity and biocompatibility. However, traditional methods usually need cumbersome and stringent conditions such as high temperature and post-modification to prepare the functionalized nHAp, which do not benefit the particles to enter cells due to the increased particle size. Herein, a biomimetic synthesis strategy was explored to achieve the AS1411-targeted tumour dual-model bioimaging using DNA aptamer AS1411 as a template. Then, the imaging properties and the biocompatibility of the synthesized AS-nFAp:Gd/Tb were further investigated.

MATERIALS AND METHODS

The AS-nFAp:Gd/Tb was prepared under mild conditions through a one-pot procedure with AS1411 as a template. Besides, the anticancer drug DOX was loaded to AS-nFAp:Gd/Tb so as to achieve the establishment of a multifunctional nano-probe that integrated the tumour diagnosis and treatment. The AS-nFAp:Gd/Tb was characterized by transmission electron microscopy (TEM), energy disperse X-ray Spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS) spectrum, X-ray diffraction (XRD), fourier-transformed infrared (FTIR) spectroscopy, capillary electrophoresis analyses, zeta potential and particle sizes. The in vitro magnetic resonance imaging (MRI) and fluorescence imaging were performed on an MRI system and a confocal laser scanning microscope, respectively. The potential of the prepared multifunctional nHAp for a targeted tumour therapy was investigated by a CCK-8 kit. And the animal experiments were conducted on the basis of the guidelines approved by the Animal Care and Use Committee of Sichuan University, China.

RESULTS

In the presence of AS1411, the as-prepared AS-nFAp:Gd/Tb presented a needle-like morphology with good monodispersity and improved imaging performance. Furthermore, due to the specific binding between AS1411 and nucleolin up-expressed in cancer cells, the AS-nFAp:Gd/Tb possessed excellent AS1411-targeted fluorescence and MRI imaging properties. Moreover, after loading chemotherapy drug DOX, in vitro and in vivo studies showed that DOX@AS-nFAp:Gd/Tb could effectively deliver DOX to tumour tissues and exert a highly effective tumour inhibition without systemic toxicity compared with pure DOX.

CONCLUSIONS

The results indicated that the prepared multifunctional nHAp synthesized by a novel biomimetic strategy had outstanding capabilities of recognition and treatment for the tumour and had good biocompatibility; hence, it might have a potential clinical application in the future.

Engineered Fe3O4-based nanomaterials for diagnosis and therapy of cancer

Recent developments of Fe₃O₄ NP-based theranostic nanoplatforms and their applications in tumor-targeted imaging and therapy.

Dual activatable self-assembled nanotheranostics for bioimaging and photodynamic therapy

Multifunctional nanosystems that can transport therapeutic and diagnostic agents into tumor sites and activate their respective functions via tumor-microenvironment recognition are highly desirable for clinical applications. We fabricated pH and redox dual-activatable self-assembled nanotheranostics (named as DA-SNs) via coordination-driven self-assembly of chlorin e6 (Ce6) disulfide-linked pH sensitive polymer ligand, poly (isobutylene-alt-maleic anhydride-graft-methoxy-poly (ethyleneglycol)-graft-imidazole-graft-Cystamine-Ce6) [PIMA-mPEG-API-SS-Ce6], and gadolinium ions (Gd³⁺). DA-SNs exhibited uniform particle size of ~48 nm, excellent stability, and inherent biosafety. Negatively charged DA-SNs could prolong blood circulation time (t_1/2 = 2.91 h) and improve tumor accumulation. Moreover, DA-SNs could undergo surface charge switch from negative charge to positive one in a slightly acidic tumor extracellular environment (pH 6.8), thus enhancing cellular uptake. After entering tumor cells, fluorescence, photodynamic therapeutic activity, and T₁MR contrast from DA-SNs could be activated within this intracellular environment with lowered pH and high level of GSH. Importantly, human tumors implanted in mice could be successfully visualized via distinct pH and redox dual-sensitive T₁MR contrast and fluorescence imaging, indicating that DA-SNs could serve as a dual-modal MR/fluorescence imaging probe for tumor-targeting diagnosis. In addition, DA-SNs exhibited superior photodynamic therapeutic efficiency with negligible side effects. Therefore, this DA-SN shows great promise for synergistic photodynamic therapy and diagnostic imaging.

Core-Shell-Heterostructured Magnetic-Plasmonic Nanoassemblies with Highly Retained Magnetic-Plasmonic Activities for Ultrasensitive Bioanalysis in Complex Matrix

Herein, a facile self-assembly strategy for coassembling oleic acid-coated iron oxide nanoparticles (OC-IONPs) with oleylamine-coated gold nanoparticles (OA-AuNPs) to form colloidal magnetic-plasmonic nanoassemblies (MPNAs) is reported. The resultant MPNAs exhibit a typical core-shell heterostructure comprising aggregated OA-AuNPs as a plasmonic core surrounded by an assembled magnetic shell of OC-IONPs. Owing to the high loading of OA-AuNPs and reasonable spatial distribution of OC-IONPs, the resultant MPNAs exhibit highly retained magnetic-plasmonic activities simultaneously. Using the intrinsic dual functionality of MPNAs as a magnetic separator and a plasmonic signal transducer, it is demonstrated that the assembled MPNAs can achieve the simultaneous magnetic manipulation and optical detection on the lateral flow immunoassay platform after surface functionalization with recognition molecules. In conclusion, the core-shell-heterostructured MPNAs can serve as a nanoanalytical platform for the separation and concentration of target compounds from complex biological samples using magnetic properties and simultaneous optical sensing using plasmonic properties.

Ag@Fe3O4@C nanoparticles for multi-modal imaging-guided chemo-photothermal synergistic targeting for cancer therapy

Novel multifunctional core-shell nanoparticles (NPs) have attracted widespread attention due to their easy-to-modify surface properties and abundant functional groups. This study introduces a facile approach to synthesize Ag@ iron oxide (Fe₃O₄) @C NPs, and modify with amino-poly (ethylene glycol) (PEG)-carboxyl and folate (FA) on the exposed carbon surface to produce high contrast for excellent stability, good biocompatibility, cancer cell targeting, and synergistic treatment. The multi-armed PEG at the edge of Ag@Fe₃O₄@C NPs provides the materials an excellent capacity for doxorubicin (DOX) loading. The carbon layer could be used as a photothermal reagent due to its excellent near-infrared (NIR) absorbance capacity, and Fe₃O₄ was used as a reagent for magnetic resonance (MR) imaging. In vivo combination therapy with this agent was administered in a mouse tumor model, and a remarkable synergistic antitumor effect that is superior to that obtained by monotherapy was achieved. Concerning these features together, these unique multifunctional Ag@Fe₃O₄@C-PEG-FA/DOX NPs could be regarded as an attractive nanoplatforms for chemo-photothermal synergistic tumor therapy with dual-modal fluorescence and MR imaging-guided targeting.

Oxidation-Responsive, EuII/III-Based, Multimodal Contrast Agent for Magnetic Resonance and Photoacoustic Imaging

We report, for the first time, a multimodal, oxidation-responsive contrast agent for magnetic resonance imaging and photoacoustic imaging that uses the differences in the properties between Eu in the +2 and +3 oxidation states. The enhancement of contrast in T1-weighted magnetic resonance and photoacoustic imaging was observed in the +2 but not in the +3 oxidation state, and the complex is a known chemical exchange saturation transfer agent for magnetic resonance imaging in the +3 oxidation state.

Fluorescence and Magnetic Resonance Dual-Modality Imaging-Guided Photothermal and Photodynamic Dual-Therapy with Magnetic Porphyrin-Metal Organic Framework Nanocomposites

Phototherapy shows some unique advantages in clinical application, such as remote controllability, improved selectivity, and low bio-toxicity, than chemotherapy. In order to improve the safety and therapeutic efficacy, imaging-guided therapy seems particularly important because it integrates visible information to speculate the distribution and metabolism of the probe. Here we prepare biocompatible core-shell nanocomposites for dual-modality imaging-guided photothermal and photodynamic dual-therapy by the in situ growth of porphyrin-metal organic framework (PMOF) on Fe3O4@C core. Fe3O4@C core was used as T2-weighted magnetic resonance (MR) imaging and photothermal therapy (PTT) agent. The optical properties of porphyrin were well remained in PMOF, and PMOF was therefore selected for photodynamic therapy (PDT) and fluorescence imaging. Fluorescence and MR dual-modality imaging-guided PTT and PDT dual-therapy was confirmed with tumour-bearing mice as model. The high tumour accumulation of Fe3O4@C@PMOF and controllable light excitation at the tumour site achieved efficient cancer therapy, but low toxicity was observed to the normal tissues. The results demonstrated that Fe3O4@C@PMOF was a promising dual-imaging guided PTT and PDT dual-therapy platform for tumour diagnosis and treatment with low cytotoxicity and negligible in vivo toxicity.

Phage display-derived oligopeptide-functionalized probes for in vivo specific photoacoustic imaging of osteosarcoma

Specific detection of various tumor types remains crucial for designing effective treatment strategies. We demonstrate photoacoustic imaging (PAI) using high-affinity and high-specificity peptide-based probes for accurate and specific diagnosis of osteosarcoma. Herein, two new tumor-specific oligopeptides, termed PT6 and PT7, were identified using phage display-based screening on an osteosarcoma cell line (UMR-106). The identified oligopeptides were able to detect clinical osteosarcoma samples on tissue microarrays. Oligopeptide-conjugated PEGylated gold nanorods (PGNR) were designed to specifically target UMR-106 cells. More importantly, PAI revealed that both PGNR-PT6 and PGNR-PT7 could bind selectively to subcutaneous UMR-106 xenografts after systemic administration and enhance the contrast of osteosarcoma images by 170% and 230%, respectively, compared to tumor-bearing mice injected with PGNRs conjugated to scrambled oligopeptides. PAI employing PGNRs conjugated to specifically designed nanoprobes may provide a new method for tumor type-specific diagnosis of osteosarcoma.

Coordination-Induced Assembly of Intelligent Polysaccharide-Based Phototherapeutic Nanoparticles for Cancer Treatment

Smart polysaccharide-based anticancer phototherapeutic nanoparticles are prepared via a coordination-induced assembly process. Upon irradiated with a near infrared laser, the nanoparticles are not only able to simultaneously generate reactive oxygen species and hyperthermia that ablate tumors, but also possess tumor microenvironment-responsive off/on near infrared fluorescence and enhancement in photothermal effect, making them promising theranostic platform of cancer.

Current and Emerging Clinical Applications of Multispectral Optoacoustic Tomography (MSOT) in Oncology

Accurate detection and characterization of cancers are key for providing timely intervention and effective treatments. Current imaging technologies are particularly limited when it comes to detecting very small tumors in vivo, i.e., very early cancers or metastases, differentiating viable tumor from surrounding dead tumor tissue, and evaluating tumor metabolism within tissue. Optoacoustic imaging offers potential solutions to these imaging problems because of its ability to image optical absorption properties of both intrinsic tissue chromophores and exogenous contrast agents without the involvement of ionizing radiation. Optoacoustic imaging uses pulsed laser to induce localized thermoelastic expansion that generates acoustic waves detectable by an ultrasound transducer. To date, multispectral optoacoustic tomography (MSOT) has primarily been used in preclinical research; however, its use in translational and clinical research is expanding. This review focuses on current and emerging applications of optoacoustic imaging for molecular imaging of cancer using both exogenous and endogenous contrast agents and sheds light on potential future clinical applications. Clin Cancer Res; 22(14); 3432-9. ©2016 AACR.

Near-infrared emissive lanthanide hybridized carbon quantum dots for bioimaging applications

Facile preparation of lanthanide hybridized carbon quantum dots (Ln-CQDs) and their potential for visible/NIR bioimagingin vivo.

Fluorescence and photochromic properties of a series of new Zn(ii)/Cd(ii) coordination compounds with a flexible semi-rigid tetrazole–viologen derivative

Diverse luminescence has been realized in four Zn(ii)/Cd(ii) coordination compounds. The isolated binuclear compound displays fluorescence and second-order nonlinear optical property variation in the photochromic process.

Developing Mn-doped lead sulfide quantum dots for MRI labels

Magnetic interactions of Mn²⁺ ions in lead sulfide (PbS) nanocrystals with protons in water are probed by NMR and MRI.