Combined Positron Emission Tomography and Cerenkov Luminescence Imaging of Sentinel Lymph Nodes Using PEGylated Radionuclide-Embedded Gold Nanoparticles

Nano-tracers for sentinel lymph node detection: current trends in technique and application

Sentinel lymph node (SLN) detection and biopsy is a critical staging component for several cancers. Apart from established methods using dyes or radiolabeled colloids, newer techniques are emerging, like near-infrared fluorescent compounds, targeted molecular radiopharmaceuticals and magnetic nano-tracers. In the overview section of this review, we categorize SLN detection tracers based on their principle of use. We discuss the merits of existing tracers and provide a glimpse of in-development formulations. A subsequent clinical section explores the expanded role of SLN detection in management of various cancers, citing current medical guidelines and the leading conclusions of long-term clinical trials. The concluding section tries to provide a perspective of promising developments and the work required to bring them to clinical fruition.

Hybrid AuNPs-3MPS-MTX nanosystem and its evaluation for treating cervical cancer and melanoma

This research presents an evaluation of a hybrid material based on gold nanoparticles (AuNPs), stabilized with the thiol 3-mercapto-propanesulfonate (3MPS) and loaded with the methotrexate drug (MTX). The AuNPs-3MPS-MTX nanosystem was tested for the treatment of cervical cancer and melanoma, using the B16-F10 melanoma and HeLa cell lines. The tests performed on cell cultures assessed the efficiency of the studied nanosystem on tumor cells, as well as its toxicology.

PET/Fluorescence Imaging: An Overview of the Chemical Strategies to Build Dual Imaging Tools

Molecular imaging is a biomedical research discipline that has quickly emerged to afford the observation, characterization, monitoring, and quantification of biomarkers and biological processes in living organism. It covers a large array of imaging techniques, each of which provides anatomical, functional, or metabolic information. Multimodality, as the combination of two or more of these techniques, has proven to be one of the best options to boost their individual properties, hence offering unprecedented tools for human health. In this review, we will focus on the combination of positron emission tomography and fluorescence imaging from the specific perspective of the chemical synthesis of dual imaging agents. Based on a detailed analysis of the literature, this review aims at giving a comprehensive overview of the chemical strategies implemented to build adequate imaging tools considering radiohalogens and radiometals as positron emitters, fluorescent dyes mostly emitting in the NIR window and all types of targeting vectors.

The bright future of nanotechnology in lymphatic system imaging and imaging-guided surgery

Lymphatic system is identified the second vascular system after the blood circulation in mammalian species, however the research on lymphatic system has long been hampered by the lack of comprehensive imaging modality. Nanomaterials have shown the potential to enhance the quality of lymphatic imaging due to the unparalleled advantages such as the specific passive targeting and efficient co-delivery of cocktail to peripheral lymphatic system, ease molecular engineering for precise active targeting and prolonged retention in the lymphatic system of interest. Multimodal lymphatic imaging based on nanotechnology provides a complementary means to understand the kinetics of lymphoid tissues and quantify its function. In this review, we introduce the established approaches of lymphatic imaging used in clinic and summarize their strengths and weaknesses, and list the critical influence factors on lymphatic imaging. Meanwhile, the recent developments in the field of pre-clinical lymphatic imaging are discussed to shed new lights on the design of new imaging agents, the improvement of delivery methods and imaging-guided surgery strategies.

Discovery of novel phenaleno isoquinolinium-based fluorescence imaging agents for sentinel lymph node mapping

Fluorescence imaging agents have recently received huge attention due to their important role in disease diagnostics. However, the intrinsic problems of these probes, such as complex synthetic routes and high molecular weight, remain challenging. Here, we developed novel phenaleno isoquinolinium-based fluorescent agents, Medical Fluorophores 37-41 (MF37-41), applicable to the quantitative and sensitive detection of sentinel lymph nodes (SLNs). These imaging agents showed no adverse effects on the proliferation of immune and normal cells and did not induce in vivo toxicity. In vivo fluorescence lifetime imaging demonstrated the accumulation of phenaleno isoquinolinium salts in the SLNs of nude mice within 15 min postinjection, consistent with our biodistribution findings. These results suggest that phenaleno isoquinolinium salts are feasible fluorescence imaging agents that can be used as potential lymphatic tracers.

Optimization of Sentinel Lymph Node Imaging Methodology Using Anionic Liposome and Hyaluronidase

The sentinel lymph node (SLN) is the first lymph node into which lymphatic fluid from tumor tissues flows. The development of a highly sensitive probe for detecting SLNs is desired for the lymph node dissection through intraoperative biopsy. We have previously shown that anionic liposomes tend to accumulate in lymph nodes and that macrophage uptake of liposomes contributes to their accumulation. In the present study, we found that among anionic lipids, phosphatidylserine (PS)-containing liposomes were substantially taken up by macrophages. We identified a new lipid composition to improve the SNL-selectivity of liposome accumulation based on Design-of-Experiment. The optimized PS-containing particles were more selectively accumulate to SLN lymph nodes than existing imaging agents indocyanine green. These results indicate the effectiveness of PS-containing anionic particles in SLN imaging.

Gold nanoparticles meet medical radionuclides

Thanks to their unique optical and physicochemical properties, gold nanoparticles have gained increased interest as radiosensitizing, photothermal therapy and optical imaging agents to enhance the effectiveness of cancer detection and therapy. Furthermore, their ability to carry multiple medically relevant radionuclides broadens their use to nuclear medicine SPECT and PET imaging as well as targeted radionuclide therapy. In this review, we discuss the radiolabeling process of gold nanoparticles and their use in (multimodal) nuclear medicine imaging to better understand their specific distribution, uptake and retention in different in vivo cancer models. In addition, radiolabeled gold nanoparticles enable image-guided therapy is reviewed as well as the enhancement of targeted radionuclide therapy and nanobrachytherapy through an increased dose deposition and radiosensitization, as demonstrated by multiple Monte Carlo studies and experimental in vitro and in vivo studies.

Radiopharmaceutical and Eu3+ doped gadolinium oxide nanoparticles mediated triple-excited fluorescence imaging and image-guided surgery

Cerenkov luminescence imaging (CLI) is a novel optical imaging technique that has been applied in clinic using various radionuclides and radiopharmaceuticals. However, clinical application of CLI has been limited by weak optical signal and restricted tissue penetration depth. Various fluorescent probes have been combined with radiopharmaceuticals for improved imaging performances. However, as most of these probes only interact with Cerenkov luminescence (CL), the low photon fluence of CL greatly restricted it's interaction with fluorescent probes for in vivo imaging. Therefore, it is important to develop probes that can effectively convert energy beyond CL such as β and γ to the low energy optical signals. In this study, a Eu3+ doped gadolinium oxide (Gd2O3:Eu) was synthesized and combined with radiopharmaceuticals to achieve a red-shifted optical spectrum with less tissue scattering and enhanced optical signal intensity in this study. The interaction between Gd2O3:Eu and radiopharmaceutical were investigated using 18F-fluorodeoxyglucose (18F-FDG). The ex vivo optical signal intensity of the mixture of Gd2O3:Eu and 18F-FDG reached 369 times as high as that of CLI using 18F-FDG alone. To achieve improved biocompatibility, the Gd2O3:Eu nanoparticles were then modified with polyvinyl alcohol (PVA), and the resulted nanoprobe PVA modified Gd2O3:Eu (Gd2O3:Eu@PVA) was applied in intraoperative tumor imaging. Compared with 18F-FDG alone, intraoperative administration of Gd2O3:Eu@PVA and 18F-FDG combination achieved a much higher tumor-to-normal tissue ratio (TNR, 10.24 ± 2.24 vs. 1.87 ± 0.73, P = 0.0030). The use of Gd2O3:Eu@PVA and 18F-FDG also assisted intraoperative detection of tumors that were omitted by preoperative positron emission tomography (PET) imaging. Further experiment of image-guided surgery demonstrated feasibility of image-guided tumor resection using Gd2O3:Eu@PVA and 18F-FDG. In summary, Gd2O3:Eu can achieve significantly optimized imaging property when combined with 18F-FDG in intraoperative tumor imaging and image-guided tumor resection surgery. It is expected that the development of the Gd2O3:Eu nanoparticle will promote investigation and application of novel nanoparticles that can interact with radiopharmaceuticals for improved imaging properties. This work highlighted the impact of the nanoprobe that can be excited by radiopharmaceuticals emitting CL, β, and γ radiation for precisely imaging of tumor and intraoperatively guide tumor resection.

Visualization of platelet recruitment to tumor lesions using highly sensitive and stable radioiodine studded gold nanoprobes

In vivo imaging of platelets will provide a better understanding of their critical roles in arterial cardiovascular disease, hemostasis, inflammation, and cancer. Here, we demonstrate the feasibility of using radioiodine studded gold nanoprobes (RIS-GNPs) as a platelet tracker for nuclear medicine imaging in tumor-bearing mice using positron emission tomography and computed tomography (PET/CT). Platelet labeling with RIS-GNPs did not alter the platelet functions, such as cellular proliferation and aggregation. PET/CT imaging clearly revealed the migration of platelets into tumor sites at 1 to 5 h post-transfer of RIS-GNP-labeled platelets, which was consistent with the biodistribution data. Our findings suggest that the imaging approach using RIS-GNPs makes it feasible to visualize the biological behavior of platelets in living organisms with cancer.

Radiolabeled Gold Nanoparticles for Imaging and Therapy of Cancer

In the Last decades, nanotechnology has provided novel and alternative methodologies and tools in the field of medical oncology, in order to tackle the issues regarding the control and treatment of cancer in modern society. In particular, the use of gold nanoparticles (AuNPs) in radiopharmaceutical development has provided various nanometric platforms for the delivery of medically relevant radioisotopes for SPECT/PET diagnosis and/or radionuclide therapy. In this review, we intend to provide insight on the methodologies used to obtain and characterize radiolabeled AuNPs while reporting relevant examples of AuNPs developed during the last decade for applications in nuclear imaging and/or radionuclide therapy, and highlighting the most significant preclinical studies and results.

Nanoparticles for Cerenkov and Radioluminescent Light Enhancement for Imaging and Radiotherapy

Cerenkov luminescence imaging and Cerenkov photodynamic therapy have been developed in recent years to exploit the Cerenkov radiation (CR) generated by radioisotopes, frequently used in Nuclear Medicine, to diagnose and fight cancer lesions. For in vivo detection, the endpoint energy of the radioisotope and, thus, the total number of the emitted Cerenkov photons, represents a very important variable and explains why, for example, ⁶⁸Ga is better than ¹⁸F. However, it was also found that the scintillation process is an important mechanism for light production. Nanotechnology represents the most important field, providing nanosctructures which are able to shift the UV-blue emission into a more suitable wavelength, with reduced absorption, which is useful especially for in vivo imaging and therapy applications. Nanoparticles can be made, loaded or linked to fluorescent dyes to modify the optical properties of CR radiation. They also represent a useful platform for therapeutic agents, such as photosensitizer drugs for the production of reactive oxygen species (ROS). Generally, NPs can be spaced by CR sources; however, for in vivo imaging applications, NPs bound to or incorporating radioisotopes are the most interesting nanocomplexes thanks to their high degree of mutual colocalization and the reduced problem of false uptake detection. Moreover, the distance between the NPs and CR source is crucial for energy conversion. Here, we review the principal NPs proposed in the literature, discussing their properties and the main results obtained by the proponent experimental groups.

Optical Imaging Modalities: Principles and Applications in Preclinical Research and Clinical Settings

With the ability to noninvasively image and monitor molecular processes within tumors, molecular imaging represents a fundamental tool for cancer scientists. In the current review, we describe emergent optical technologies for molecular imaging. We aim to provide the reader with an overview of the fundamental principles on which each imaging strategy is based, to introduce established and future applications, and to provide a rationale for selecting optical technologies for molecular imaging depending on disease location, biology, and anatomy. To accelerate clinical translation of imaging techniques, we also describe examples of practical applications in patients. Elevating these techniques into standard-of-care tools will transform patient stratification, disease monitoring, and response evaluation.

Hybrid (2D/3D) Dosimetry of Radiolabeled Gold Nanoparticles for Sentinel Lymph Node Detection in Patients with Breast Cancer

Previously, we reported the preparation and preclinical studies of ^99mTc-labeled gold nanoparticles-mannose (^99mTc-AuNP-mannose) with potential for sentinel lymph node (SLN) detection by using nuclear medicine procedures. This study aimed to evaluate the biokinetics and hybrid (2D/3D) dosimetry of ^99mTc-AuNP-mannose in five patients with breast cancer under a sentinel lymph node detection protocol. Anterior and posterior whole-body planar images (2D, at 0.5, 2, 6, and 24 h) and single-photon emission computed tomography (3D at 6.5 h)/computed tomography (SPECT/CT) images were acquired after ^99mTc-AuNP-mannose administration (37 MBq). Through a hybrid quantification method, activity in tissues of interest at the different acquisition times was determined and integrated over time to obtain the total nuclear transformations (N), as well as the mean residence time, in each tissue. N values and the OLINDA code were used for estimating the internal radiation absorbed doses. Results demonstrated that ^99mTc-AuNP-mannose successfully accumulates and remains up to 24 h in the sentinel lymph node without detectable migration to other lymph nodes and no side effects on patients. Negligible absorption of the radiolabeled nanoparticles into the circulatory system was observed, from which the radio-nanosystem is rapidly eliminated by kidneys. Hybrid (2D/3D) dosimetry evaluations showed equivalent doses to SLN, breast, and kidneys of 172.34, 5.32, and 0.08 mSv/37 MBq, respectively, with an effective dose of 2.05E - 03 mSv/MBq. The mean effective residence time in SLN was 0.92 h. This preliminary study indicates that the use of ^99mTc-AuNP-mannose for successful SLN detection in patients is safe, producing an effective dose at the level recommended for diagnostic studies (<10 mSv).

Fluorescence resonance energy transfer-based drug delivery systems for enhanced photodynamic therapy

In this Review, recent advances in fluorescence resonance energy transfer-based drug delivery systems for enhanced photodynamic therapy are described, and the current challenges and perspectives in this emerging field are also discussed.

Advanced Nanotechnology Leading the Way to Multimodal Imaging-Guided Precision Surgical Therapy

Surgical resection is the primary and most effective treatment for most patients with solid tumors. However, patients suffer from postoperative recurrence and metastasis. In the past years, emerging nanotechnology has led the way to minimally invasive, precision and intelligent oncological surgery after the rapid development of minimally invasive surgical technology. Advanced nanotechnology in the construction of nanomaterials (NMs) for precision imaging-guided surgery (IGS) as well as surgery-assisted synergistic therapy is summarized, thereby unlocking the advantages of nanotechnology in multimodal IGS-assisted precision synergistic cancer therapy. First, mechanisms and principles of NMs to surgical targets are briefly introduced. Multimodal imaging based on molecular imaging technologies provides a practical method to achieve intraoperative visualization with high resolution and deep tissue penetration. Moreover, multifunctional NMs synergize surgery with adjuvant therapy (e.g., chemotherapy, immunotherapy, phototherapy) to eliminate residual lesions. Finally, key issues in the development of ideal theranostic NMs associated with surgical applications and challenges of clinical transformation are discussed to push forward further development of NMs for multimodal IGS-assisted precision synergistic cancer therapy.

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.

Gold Nanoparticles and Nanorods in Nuclear Medicine: A Mini Review

In the last decade, many innovative nanodrugs have been developed, as well as many nanoradiocompounds that show amazing features in nuclear imaging and/or radiometabolic therapy. Their potential uses offer a wide range of possibilities. It can be possible to develop nondimensional systems of existing radiopharmaceuticals or build engineered systems that combine a nanoparticle with the radiopharmaceutical, a tracer, and a target molecule, and still develop selective nanodetection systems. This review focuses on recent advances regarding the use of gold nanoparticles and nanorods in nuclear medicine. The up-to-date advancements will be shown concerning preparations with special attention on the dimensions and functionalizations that are most used to attain an enhanced performance of gold engineered nanomaterials. Many ideas are offered regarding recent in vitro and in vivo studies. Finally, the recent clinical trials and applications are discussed.

Radiopharmaceuticals and Fluorescein Sodium Mediated Triple-Modality Molecular Imaging Allows Precise Image-Guided Tumor Surgery

Radical resection is the most effective method for malignant tumor treatments. However, conventional imaging cannot fully satisfy the clinical needs of surgical navigation. This study presents a novel triple-modality positron emission tomography (PET)-Cerenkov radiation energy transfer (CRET)-confocal laser endomicroscopy (CLE) imaging strategy for intraoperative tumor imaging and surgical navigation. Using clinical radiopharmaceuticals and fluorescein sodium (FS), this strategy can accurately detect the tumor and guide the tumor surgery. The FS emission property under Cerenkov radiation excitation is investigated using 2-deoxy-2-18F-fluoroglucose and 11C-choline. Performances of the PET-CRET-CLE imaging and the CRET-CLE image-guided surgery are evaluated on mouse models. The CRET signal at 8 mm depth is stronger than the Cerenkov luminescence at 1 mm depth in phantoms. In vivo experiments indicate that 0.5 mL kg-1 of 10% FS generates the strongest CRET signal, which can be observed immediately after FS injection. A surgical navigation study shows that the tumors are precisely detected and resected using intraoperative CRET-CLE. In summary, a PET-CRET-CLE triple-modality imaging strategy is developed. This strategy can detect the tumors and precisely guide the tumor resection using clinical pharmaceuticals. This triple-modality imaging shows high potential in surgical navigation research and clinical translation.

Probing the biological obstacles of nanomedicine with gold nanoparticles

Despite massive growth in nanomedicine research to date, the field still lacks fundamental understanding of how certain physical and chemical features of a nanoparticle affect its ability to overcome biological obstacles in vivo and reach its intended target. To gain fundamental understanding of how physical and chemical parameters affect the biological outcomes of administered nanoparticles, model systems that can systematically manipulate a single parameter with minimal influence on others are needed. Gold nanoparticles are particularly good model systems in this case as one can synthetically control the physical dimensions and surface chemistry of the particles independently and with great precision. Additionally, the chemical and physical properties of gold allow particles to be detected and quantified in tissues and cells with high sensitivity. Through systematic biological studies using gold nanoparticles, insights toward rationally designed nanomedicine for in vivo imaging and therapy can be obtained. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Antigen-Free Radionuclide-Embedded Gold Nanoparticles for Dendritic Cell Maturation, Tracking, and Strong Antitumor Immunity

Dendritic cell (DC)-based cancer immunotherapy requires efficient maturation of DCs and sensitive monitoring of DCs localized in the lymph nodes that activate T cells. This paper reports a robust and simple surface chemistry for highly sensitive and stable radionuclide-embedded gold nanoparticles (Poly-Y-RIe-AuNPs) prepared with oligotyrosine-modified AuNPs with additional Au shell formation as a promising positron emission tomography/computed tomography imaging agent. The multiple oligotyrosine binding sites modified on AuNPs provide excellent stability for conjugated radioisotopes by forming an Au shell. They can be heavily conjugated with radioisotope iodine, which enables sensitive tracking of DCs in the lymphatic system. More importantly, it is found that the maturation of DCs is possible solely with Poly-Y-RIe-AuNPs without any additional stimulus for DC maturation. DCs matured by Poly-Y-RIe-AuNPs induce antitumor immunity to cervical cancer comparable to that produced from DCs pulsated with tumor lysates. These results demonstrate that the peptide-based surface chemistry of Poly-Y-RIe-AuNPs is a simple and straightforward method to produce a highly sensitive and stable nuclear medicine imaging agent that also improves the efficiency of current antitumor immunotherapies.

Tumor-targeting CuS nanoparticles for multimodal imaging and guided photothermal therapy of lymph node metastasis

Precise diagnosis of lymph node metastasis to guide lymphadenectomy is highly important for gastric cancer therapy in clinics. Though surgical dissection of regional metastatic lymph nodes remains the only way for gastric cancer therapy, the extended dissection may cause unavoidable postoperative risk of complications. It is still lack of effective method enabling the accurate removal of metastatic gastric cancer cells in lymph nodes with minimum injuries to normal tissue. Herein, we report a new fluorescent copper sulfide (CuS) nanoparticle (RGD-CuS-Cy5.5) enabling both non-invasive multimodality imaging and targeting photothermal therapy (PTT) of metastatic gastric cancer cells in lymph nodes. We demonstrate that RGD-CuS-Cy5.5 can easily drain into sentinel lymph nodes (SLN) after injection into primary tumors, and selectively enter into metastatic gastric MNK45 tumor cells via α_vβ₃ integrin-mediated endocytosis. The resulting strong near-infrared (NIR) fluorescence and computed tomography (CT) contrast in metastatic SLN compared to normal SLN can precisely differentiate SLN metastasis of gastric cancers. Guided by the imaging, localized PTT with RGD-CuS-Cy5.5 is conducted upon irradiation with an 808 nm laser, resulting in complete removal of metastatic gastric tumor cells in SLN without obvious toxicity. Moreover, RGD-CuS-Cy5.5 can also allow for the rapid and non-invasive self-monitoring of PTT efficacy against metastatic SLNs in living mice. This study highlights the potential of using RGD-CuS-Cy5.5 for imaging-guided and targeting PTT of SLN metastasis in vivo, which may be applicable for the metastatic gastric cancer therapy in clinics.

STATEMENT OF SIGNIFICANCE

RGD-CuS-Cy5.5 nanoparticles possess NIR fluorescence and CT signals for in vivo bimodality imaging of lymph node metastasis. Strong photothermal property under irradiation at 808 nm for efficient PTT. Easy drain into sentinel lymph nodes and selective enter metastatic gastric cancer cells via α_vβ₃ integrin-mediated endocytosis. Rapid and non-invasive monitoring of therapeutic efficacy against lymph node metastasis.

PEGylated crushed gold shell-radiolabeled core nanoballs for in vivo tumor imaging with dual positron emission tomography and Cerenkov luminescent imaging

BACKGROUND

Radioactive isotope-labeled gold nanomaterials have potential biomedical applications. Here, we report the synthesis and characterization of PEGylated crushed gold shell-radioactive iodide-124-labeled gold core nanoballs (PEG-¹²⁴I-Au@AuCBs) for in vivo tumor imaging applications through combined positron emission tomography and Cerenkov luminescent imaging (PET/CLI).

RESULTS

PEG-¹²⁴I-Au@AuCBs showed high stability and sensitivity in various pH solutions, serum, and in vivo conditions and were not toxic to tested cells. Combined PET/CLI clearly revealed tumor lesions at 1 h after injection of particles, and both signals remained visible in tumor lesions at 24 h, consistent with the biodistribution results.

CONCLUSION

Taken together, the data provided strong evidence for the application of PEG-¹²⁴I-Au@AuCBs as promising imaging agents in nuclear medicine imaging of various biological systems, particularly in cancer diagnosis.

Practical Guidelines for Cerenkov Luminescence Imaging with Clinically Relevant Isotopes

Cerenkov luminescence imaging (CLI) is a relatively new imaging modality that utilizes conventional optical imaging instrumentation to detect Cerenkov radiation derived from standard and often clinically approved radiotracers. Its research versatility, low cost, and ease of use have increased its popularity within the molecular imaging community and at institutions that are interested in conducting radiotracer-based molecular imaging research, but that lack the necessary resources and infrastructure. Here, we provide a description of the materials and procedures necessary to conduct a Cerenkov luminescence imaging experiment using a variety of imaging instrumentation, radionuclides, and animal models.

Molecular Imaging in Nanotechnology and Theranostics

The fields of biomedical nanotechnology and theranostics have enjoyed exponential growth in recent years. The "Molecular Imaging in Nanotechnology and Theranostics" (MINT) Interest Group of the World Molecular Imaging Society (WMIS) was created in order to provide a more organized and focused forum on these topics within the WMIS and at the World Molecular Imaging Conference (WMIC). The interest group was founded in 2015 and was officially inaugurated during the 2016 WMIC. The overarching goal of MINT is to bring together the many scientists who work on molecular imaging approaches using nanotechnology and those that work on theranostic agents. MINT therefore represents scientists, labs, and institutes that are very diverse in their scientific backgrounds and areas of expertise, reflecting the wide array of materials and approaches that drive these fields. In this short review, we attempt to provide a condensed overview over some of the key areas covered by MINT. Given the breadth of the fields and the given space constraints, we have limited the coverage to the realm of nanoconstructs, although theranostics is certainly not limited to this domain. We will also focus only on the most recent developments of the last 3-5 years, in order to provide the reader with an intuition of what is "in the pipeline" and has potential for clinical translation in the near future.

Nanoparticles as Theranostic Vehicles in Experimental and Clinical Applications-Focus on Prostate and Breast Cancer

Prostate and breast cancer are the second most and most commonly diagnosed cancer in men and women worldwide, respectively. The American Cancer Society estimates that during 2016 in the USA around 430,000 individuals were diagnosed with one of these two types of cancers, and approximately 15% of them will die from the disease. In Europe, the rate of incidences and deaths are similar to those in the USA. Several different more or less successful diagnostic and therapeutic approaches have been developed and evaluated in order to tackle this issue and thereby decrease the death rates. By using nanoparticles as vehicles carrying both diagnostic and therapeutic molecular entities, individualized targeted theranostic nanomedicine has emerged as a promising option to increase the sensitivity and the specificity during diagnosis, as well as the likelihood of survival or prolonged survival after therapy. This article presents and discusses important and promising different kinds of nanoparticles, as well as imaging and therapy options, suitable for theranostic applications. The presentation of different nanoparticles and theranostic applications is quite general, but there is a special focus on prostate cancer. Some references and aspects regarding breast cancer are however also presented and discussed. Finally, the prostate cancer case is presented in more detail regarding diagnosis, staging, recurrence, metastases, and treatment options available today, followed by possible ways to move forward applying theranostics for both prostate and breast cancer based on promising experiments performed until today.

Utilizing the power of Cerenkov light with nanotechnology

The characteristic blue glow of Cerenkov luminescence (CL) arises from the interaction between a charged particle travelling faster than the phase velocity of light and a dielectric medium, such as water or tissue. As CL emanates from a variety of sources, such as cosmic events, particle accelerators, nuclear reactors and clinical radionuclides, it has been used in applications such as particle detection, dosimetry, and medical imaging and therapy. The combination of CL and nanoparticles for biomedicine has improved diagnosis and therapy, especially in oncological research. Although radioactive decay itself cannot be easily modulated, the associated CL can be through the use of nanoparticles, thus offering new applications in biomedical research. Advances in nanoparticles, metamaterials and photonic crystals have also yielded new behaviours of CL. Here, we review the physics behind Cerenkov luminescence and associated applications in biomedicine. We also show that by combining advances in nanotechnology and materials science with CL, new avenues for basic and applied sciences have opened.

Radiolabeled inorganic nanoparticles for positron emission tomography imaging of cancer: an overview

Over the last few years, a plethora of radiolabeled inorganic nanoparticles have been developed and evaluated for their potential use as probes in positron emission tomography (PET) imaging of a wide variety of cancers. Inorganic nanoparticles represent an emerging paradigm in molecular imaging probe design, allowing the incorporation of various imaging modalities, targeting ligands, and therapeutic payloads into a single vector. A major challenge in this endeavor is to develop disease-specific nanoparticles with facile and robust radiolabeling strategies. Also, the radiolabeled nanoparticles should demonstrate adequate in vitro and in vivo stability, enhanced sensitivity for detection of disease at an early stage, optimized in vivo pharmacokinetics for reduced non-specific organ uptake, and improved targeting for achieving high efficacy. Owing to these challenges and other technological and regulatory issues, only a single radiolabeled nanoparticle formulation, namely "C-dots" (Cornell dots), has found its way into clinical trials thus far. This review describes the available options for radiolabeling of nanoparticles and summarizes the recent developments in PET imaging of cancer in preclinical and clinical settings using radiolabeled nanoparticles as probes. The key considerations toward clinical translation of these novel PET imaging probes are discussed, which will be beneficial for advancement of the field.