Advanced Methods for Radiolabeling Multimodality Nanomedicines for SPECT/MRI and PET/MRI

Multimodal and multifunctional nanoparticles with platelet targeting ability and phase transition efficiency for the molecular imaging and thrombolysis of coronary microthrombi

In this article, we constructed PLGA-cRGD-PFH-ICG NPs through emulsification process and then the bi-modal imaging of coronary microthrombi in ischemia/reperfusion rat model and thrombolysis of clots in vitro were both successfully completed by these NPs.

Nuclear imaging approaches facilitating nanomedicine translation

Nanomedicine approaches can effectively modulate the biodistribution and bioavailability of therapeutic agents, improving their therapeutic index. However, despite the ever-increasing amount of literature reporting on preclinical nanomedicine, the number of nanotherapeutics receiving FDA approval remains relatively low. Several barriers exist that hamper the effective preclinical evaluation and clinical translation of nanotherapeutics. Key barriers include insufficient understanding of nanomedicines' in vivo behavior, inadequate translation from murine models to larger animals, and a lack of patient stratification strategies. Integrating quantitative non-invasive imaging techniques in nanomedicine development offers attractive possibilities to address these issues. Among the available imaging techniques, nuclear imaging by positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are highly attractive in this context owing to their quantitative nature and uncontested sensitivity. In basic and translational research, nuclear imaging techniques can provide critical quantitative information about pharmacokinetic parameters, biodistribution profiles or target site accumulation of nanocarriers and their associated payload. During clinical evaluation, nuclear imaging can be used to select patients amenable to nanomedicine treatment. Here, we review how nuclear imaging-based approaches are increasingly being integrated into nanomedicine development and discuss future developments that will accelerate their clinical translation.

Multi-functionalised graphene nanoflakes as tumour-targeting theranostic drug-delivery vehicles

Graphene nanoflakes (GNFs) consist of a graphene sheet approximately 30 nm in diameter with a pristine aromatic system and an edge terminated with carboxylic acid groups. Their high water solubility and relative ease of functionalisation using carboxylate chemistry means that GNFs are potential scaffolds for the synthesis of theranostic agents. In this work, GNFs were multi-functionalised with derivatives of (i) a peptide-based Glu-NH-C(O)-NH-Lys ligand that binds prostate-specific membrane antigen (PSMA), (ii) a potent anti-mitotic drug (R)-ispinesib, (iii) the chelate desferrioxamine B (DFO), and (iv) an albumin-binding tag reported to extend pharmacokinetic half-life in vivo. Subsequent 68Ga radiochemistry and experiments in vitro and in vivo were used to evaluate the performance of GNFs in theranostic drug design. Efficient 68Ga-radiolabelling was achieved and the particle-loading of (R)-ispinesib and Glu-NH-C(O)-NH-Lys was confirmed using cellular assays. Using dose-response curves and FACS analysis it was shown that GNFs loaded with (R)-ispinesib inhibited the kinesin spindle protein (KSP) and induced G2/M-phase cell cycle arrest. Cellular uptake and blocking experiments demonstrated that GNFs functionalised with the Glu-NH-C(O)-NH-Lys ligand showed specificity toward PSMA expressing cells (LNCaP). The distribution profile and excretion rates of 68Ga-radiolabelled GNFs in athymic nude mice was evaluated using time-activity curves derived from dynamic positron-emission tomography (PET). Image analysis indicated that GNFs have low accumulation and retention in background tissue, with rapid renal clearance. In summary, our study shows that GNFs are suitable candidates for use in theranostic drug design.

Radionuclide-Activated Nanomaterials and Their Biomedical Applications

Radio-nanomedicine, or the use of radiolabeled nanoparticles in nuclear medicine, has attracted much attention in the last few decades. Since the discovery of Cerenkov radiation and its employment in Cerenkov luminescence imaging, the combination of nanomaterials and Cerenkov radiation emitters has been revolutionizing the way nanomaterials are perceived in the field: from simple inert carriers of radioactivity to activatable nanomaterials for both diagnostic and therapeutic applications. Herein, we provide a comprehensive review on the types of nanomaterials that have been used to interact with Cerenkov radiation and the gamma and beta scintillation of radionuclides, as well as on their biological applications.

Magnetic Nanoparticles: Current Trends and Future Aspects in Diagnostics and Nanomedicine

Background:

Biomedical applications of Magnetic Nanoparticles (MNPs) are creating a major impact on disease diagnosis and nanomedicine or a combined platform called theranostics. A significant progress has been made to engineer novel and hybrid MNPs for their multifunctional modalities such as imaging, biosensors, chemotherapeutic or photothermal and antimicrobial agents. MNPs are successfully applied in biomedical applications due to their unique and tunable properties such as superparamagnetism, stability, and biocompatibility. Approval of ferumoxytol (feraheme) for MRI and the fact that several Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are currently undergoing clinical trials have paved a path for future MNPs formulations. Intensive research is being carried out in designing and developing novel nanohybrids for multiple applications in nanomedicine.

Objective:

The objective of the present review is to summarize recent developments of MNPs in imaging modalities like MRI, CT, PET and PA, biosensors and nanomedicine including their role in targeting and drug delivery. Relevant theory and examples of the use of MNPs in these applications have been cited and discussed to create a thorough understanding of the developments in this field.

Conclusion:

MNPs have found widespread use as contrast agents in imaging modalities, as tools for bio-sensing, and as therapeutic and theranostics agents. Multiple formulations of MNPs are in clinical testing and may be accepted in clinical settings in near future.

68Ga-Sienna+ for PET-MRI Guided Sentinel Lymph Node Biopsy: Synthesis and Preclinical Evaluation in a Metastatic Breast Cancer Model

Sentinel lymph node biopsy (SLNB) is commonly performed in cancers that metastasise via the lymphatic system. It involves excision and histology of sentinel lymph nodes (SLNs) and presents two main challenges: (i) sensitive whole-body localisation of SLNs, and (ii) lack of pre-operative knowledge of their metastatic status, resulting in a high number (>70%) of healthy SLN excisions. To improve SLNB, whole-body imaging could improve detection and potentially prevent unnecessary surgery by identifying healthy and metastatic SLNs. In this context, radiolabelled SPIOs and PET-MRI could find applications to locate SLNs with high sensitivity at the whole-body level (using PET) and guide high-resolution MRI to evaluate their metastatic status. Here we evaluate this approach by synthesising a GMP-compatible 68Ga-SPIO (68Ga-Sienna+) followed by PET-MR imaging and histology studies in a metastatic breast cancer mouse model. Methods. A clinically approved SPIO for SLN localisation (Sienna+) was radiolabelled with 68Ga without a chelator. Radiochemical stability was tested in human serum. In vitro cell uptake was compared between 3E.Δ.NT breast cancer cells, expressing the hNIS reporter gene, and macrophage cell lines (J774A.1; RAW264.7.GFP). NSG-mice were inoculated with 3E.Δ.NT cells. Left axillary SLN metastasis was monitored by hNIS/SPECT-CT and compared to the healthy right axillary SLN. 68Ga-Sienna+ was injected into front paws and followed by PET-MRI. Imaging results were confirmed by histology. Results.68Ga-Sienna+ was produced in high radiochemical purity (>93%) without the need for purification and was stable in vitro. In vitro uptake of 68Ga-Sienna+ in macrophage cells (J774A.1) was significantly higher (12 ± 1%) than in cancer cells (2.0 ± 0.1%; P < 0.001). SPECT-CT confirmed metastasis in the left axillary SLNs of tumour mice. In PET, significantly higher 68Ga-Sienna+ uptake was measured in healthy axillary SLNs (2.2 ± 0.9 %ID/mL), than in metastatic SLNs (1.1 ± 0.2 %ID/mL; P = 0.006). In MRI, 68Ga-Sienna+ uptake in healthy SLNs was observed by decreased MR signal in T2/T2*-weighted sequences, whereas fully metastatic SLNs appeared unchanged. Conclusion.68Ga-Sienna+ in combination with PET-MRI can locate and distinguish healthy from metastatic SLNs and could be a useful preoperative imaging tool to guide SLN biopsy and prevent unnecessary excisions.

Review of Therapeutic Applications of Radiolabeled Functional Nanomaterials

In the last two decades, various nanomaterials have attracted increasing attention in medical science owing to their unique physical and chemical characteristics. Incorporating radionuclides into conventionally used nanomaterials can confer useful additional properties compared to the original material. Therefore, various radionuclides have been used to synthesize functional nanomaterials for biomedical applications. In particular, several α- or β-emitter-labeled organic and inorganic nanoparticles have been extensively investigated for efficient and targeted cancer treatment. This article reviews recent progress in cancer therapy using radiolabeled nanomaterials including inorganic, polymeric, and carbon-based materials and liposomes. We first provide an overview of radiolabeling methods for preparing anticancer agents that have been investigated recently in preclinical studies. Next, we discuss the therapeutic applications and effectiveness of α- or β-emitter-incorporated nanomaterials in animal models and the emerging possibilities of these nanomaterials in cancer therapy.

Biosensors for Epilepsy Management: State-of-Art and Future Aspects

Epilepsy is a serious neurological disorder which affects every aspect of patients’ life, including added socio-economic burden. Unfortunately, only a few suppressive medicines are available, and a complete cure for the disease has not been found yet. Excluding the effectiveness of available therapies, the timely detection and monitoring of epilepsy are of utmost priority for early remediation and prevention. Inability to detect underlying epileptic signatures at early stage causes serious damage to the central nervous system (CNS) and irreversible detrimental variations in the organ system. Therefore, development of a multi-task solving novel smart biosensing systems is urgently required. The present review highlights advancements in state-of-art biosensing technology investigated for epilepsy diseases diagnostics and progression monitoring or both together. State of art epilepsy biosensors are composed of nano-enabled smart sensing platform integrated with micro/electronics and display. These diagnostics systems provide bio-information needed to understand disease progression and therapy optimization timely. The associated challenges related to the development of an efficient epilepsy biosensor and vision considering future prospects are also discussed in this report. This review will serve as a guide platform to scholars for understanding and planning of future research aiming to develop a smart bio-sensing system to detect and monitor epilepsy for point-of-care (PoC) applications.

Surface radio-mineralisation mediates chelate-free radiolabelling of iron oxide nanoparticles

We introduce the concept of surface radio-mineralisation (SRM) to describe the chelate-free radiolabelling of iron-oxide and ferrite nanoparticles. We demonstrate the effectiveness of SRM with both 111In and 89Zr for bare, polymer-matrix multicore, and surface-functionalised magnetite/maghemite nanoparticles; and for bare Y3Fe5O12 nanoparticles. By analogy with geological mineralisation (the hydrothermal deposition of metals as minerals in ore bodies or lodes) we demonstrate that the heat-induced and aqueous SRM process deposits radiometal-oxides onto the nanoparticle or core surfaces, passing through the matrix or coating if present, without changing the size, structure, or magnetic properties of the nanoparticle or core. We show in a mouse model followed over 7 days that the SRM is sufficient to allow quantitative, non-invasive, prolonged, whole-body localisation of injected nanoparticles with nuclear imaging.

Iron oxide nanoparticulate system as a cornerstone in the effective delivery of Tc-99 m radionuclide: a potential molecular imaging probe for tumor diagnosis

BACKGROUND

The evolution of nanoparticles has gained prominence as platforms for developing diagnostic and/or therapeutic radiotracers. This study aims to develop a novel technique for fabricating a tumor diagnostic probe based on iron oxide nanoparticles excluding the utilization of chelating ligands.

METHODS

Tc-99 m radionuclide was loaded into magnetic iron oxide nanoparticles platform (MIONPs) by sonication. ^99mTc-encapsulated MIONPs were fully characterized concerning particles size, charge, radiochemical purity, encapsulation efficiency, in-vitro stability and cytotoxicity. These merits were biologically evaluated in normal and solid tumor bearing mice via different delivery approaches.

RESULTS

^99mTc-encapsulated MIONPs probe was synthesized with average particle size 24.08 ± 7.9 nm, hydrodynamic size 52 nm, zeta potential -28 mV, radiolabeling yield 96 ± 0.83%, high in-vitro physiological stability, and appropriate cytotoxicity behavior. The in-vivo evaluation in solid tumor bearing mice revealed that the maximum tumor radioactivity accumulation (25.39 ± 0.57, 36.40 ± 0.59 and 72.61 ± 0.82%ID/g) was accomplished at 60, 60 and 30 min p.i. for intravenous, intravenous with physical magnet targeting and intratumoral delivery, respectively. The optimum T/NT ratios of 57.70, 65.00 and 87.48 were demonstrated at 60 min post I.V., I.V. with physical magnet targeting and I.T. delivery, respectively. These chemical and biological characteristics of our prepared nano-probe demonstrate highly advanced merits over the previously reported chelator mediated radiolabeled nano-formulations which reported maximum tumor uptakes in the scope of 3.65 ± 0.19 to 16.21 ± 2.56%ID/g.

CONCLUSION

Stabilized encapsulation of ^99mTc radionuclide into MIONPs elucidates a novel strategy for developing an advanced nano-sized radiopharmaceutical for tumor diagnosis. Graphical abstract ^99mTc-encapsulated MIONPs nanosized-radiopharmaceutical as molecular imaging probe for tumor diagnosis.

An overview of nanoscale radionuclides and radiolabeled nanomaterials commonly used for nuclear molecular imaging and therapeutic functions

Recent advances in the field of nanotechnology applications in nuclear medicine offer the promise of better diagnostic and therapeutic options. In recent years, increasing efforts have been focused on developing nanoconstructs that can be used as core platforms for attaching medical radionuclides with different strategies for the purposes of molecular imaging and targeted drug delivery. This review article presents an introduction to some commonly used nanomaterials with zero-dimensional, one-dimensional, two-dimensional, and three-dimensional structures, describes the various methods applied to radiolabeling of nanomaterials, and provides illustrative examples of application of the nanoscale radionuclides or radiolabeled nanocarriers in nuclear nanomedicine. Especially, the passive and active nanotargeting delivery of radionuclides with illustrating examples for tumor imaging and therapy was reviewed and summarized. The accurate and early diagnosis of cancer can lead to increased survival rates for different types of this disease. Although, the conventional single-modality diagnostic methods such as positron emission tomography/single photon emission computed tomography or MRI used for such purposes are powerful means; most of these are limited by sensitivity or resolution. By integrating complementary signal reporters into a single nanoparticulate contrast agent, multimodal molecular imaging can be performed as scalable images with high sensitivity, resolution, and specificity. The advent of radiolabeled nanocarriers or radioisotope-loaded nanomaterials with magnetic, plasmonic, or fluorescent properties has stimulated growing interest in the developing multimodality imaging probes. These new developments in nuclear nanomedicine are expected to introduce a paradigm shift in multimodal molecular imaging and thereby opening up an era of new diagnostic medical imaging agents. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 251-285, 2019.

Folate-receptor-targeted laser-activable poly(lactide-co-glycolic acid) nanoparticles loaded with paclitaxel/indocyanine green for photoacoustic/ultrasound imaging and chemo/photothermal therapy

BACKGROUND

Cancer is one of the most serious threats to human health. Precision medicine is an innovative approach to treatment, as part of which theranostic nanomedicine has been studied extensively. However, the required biocompatibility and substantial cost for the approval of nanomedicines hinder their clinical translation.

PURPOSE

We designed a novel type of theranostic nanoparticle (NP) folate-receptor-targeted laser-activatable poly(lactide-co-glycolic acid) (PLGA) NPs loaded with paclitaxel (Ptx)/indo-cyanine green (ICG)-folic acid-polyethylene glycol (PEG)-PLGA-Ptx@ICG-perfluorohexane (Pfh)- using safe and approved materials and drugs, which would facilitate clinical translation. With laser irradiation, highly efficient photothermal therapy can be achieved. Additionally, targeted NPs can be activated by near-infrared laser irradiation at a specific region, which leads to the sharp release of Ptx at areas of high folate-receptor expression and ensures a higher Ptx concentration within the tumor region, thereby leading to chemo/photothermal synergistic antitumor efficacy. Meanwhile, the NPs can be used as a dual-modality contrast agent for photoacoustic and ultrasound imaging.

MATERIALS AND METHODS

FA-PEG-PLGA-Ptx@ICG-Pfh NPs were prepared by sonification method and characterized for physicochemical properties. Cytotoxicity and in vivo biocompatibility were evaluated respectively by CCK8 assay and blood analysis. NPs as dual-modality contrast agents were evaluated by photoacoustic/ultrasound imaging system in vitro and in vivo. In vitro anticancer effect and in vivo anticancer therapy was evaluated by CCK8 assay and MDA-MB231 tumor-bearing mice model.

RESULTS

FA-PEG-PLGA-Ptx@ICG-Pfh NPs were in the size of 308±5.82 nm with negative zeta potential and showed excellent photothermal effect. The NPs could be triggered sharp release of Ptx by laser irradiation, and showed the good biocompatibility in vitro and in vivo. Through photoacoustic/ultrasound imaging, the NPs showed an excellent ability as dual-modality contrast agents in vitro and in vivo. FA-PEG-PLGA-Ptx@ICG-Pfh NPs with laser irradiation showed the best anticancer efficacy in vitro and in vivo.

CONCLUSION

Such a biocompatible and novel theranostic NP is expected to integrate dual-modality imaging with improved therapeutic efficacy and provide a promising paradigm for cancer therapy.

An Overview on Image Registration Techniques for Cardiac Diagnosis and Treatment

Image registration has been used for a wide variety of tasks within cardiovascular imaging. This study aims to provide an overview of the existing image registration methods to assist researchers and impart valuable resource for studying the existing methods or developing new methods and evaluation strategies for cardiac image registration. For the cardiac diagnosis and treatment strategy, image registration and fusion can provide complementary information to the physician by using the integrated image from these two modalities. This review also contains a description of various imaging techniques to provide an appreciation of the problems associated with implementing image registration, particularly for cardiac pathology intervention and treatments.

Pretargeting in nuclear imaging and radionuclide therapy: Improving efficacy of theranostics and nanomedicines

Pretargeted nuclear imaging and radiotherapy have recently attracted increasing attention for diagnosis and treatment of cancer with nanomedicines. This is because it conceptually offers better imaging contrast and therapeutic efficiency while reducing the dose to radiosensitive tissues compared to conventional strategies. In conventional imaging and radiotherapy, a directly radiolabeled nano-sized vector is administered and allowed to accumulate in the tumor, typically on a timescale of several days. In contrast, pretargeting is based on a two-step approach. First, a tumor-accumulating vector carrying a tag is administered followed by injection of a fast clearing radiolabeled agent that rapidly recognizes the tag of the tumor-bound vector in vivo. Therefore, pretargeting circumvents the use of long-lived radionuclides that is a necessity for sufficient tumor accumulation and target-to-background ratios using conventional approaches. In this review, we give an overview of recent advances in pretargeted imaging strategies. We will critically reflect on the advantages and disadvantages of current state-of-the-art conventional imaging approaches and compare them to pretargeted strategies. We will discuss the pretargeted imaging concept and the involved chemistry. Finally, we will discuss the steps forward in respect to clinical translation, and how pretargeted strategies could be applied to improve state-of-the-art radiotherapeutic approaches.

Biodistribution and PET imaging of 89-zirconium labeled cerium oxide nanoparticles synthesized with several surface coatings

Cerium oxide nanoparticles (CONPs) have unique surface chemistry allowing catalyst-like antioxidant properties, and are being investigated for several disease indications in medicine. Studies have utilized surface modified CONPs toward this application, but have been lacking in comprehensive biodistribution and pharmacokinetic data and a direct comparison to uncoated CONPs. We developed an enhanced single-pot synthesis of several coated CONPs and an efficient intrinsic core labeling of CONPs with the clinical PET isotope, zirconium-89, allowing detailed PET imaging and ex vivo biodistribution. All coated [89Zr]-CONPs showed benefit in terms of biodistribution compared to uncoated [89Zr]-CONPs, while retaining the intrinsic antioxidant properties. Among these, poly(acrylic acid) coated CONPs demonstrated excellent candidacy for clinical implementation due to their enhanced renal clearance and low reticuloendothelial system uptake. This work also demonstrates the value of intrinsic core labeling and PET imaging for evaluation of nanoparticle constructs to better inform future studies towards clinical use.