99mTc-labelled nanosystem as tumour imaging agent for SPECT and SPECT/CT modalities

Multi-functionalization of reduced graphene oxide nanosheets for tumor theragnosis: Synthesis, characterization, enzyme assay, in-silico study, radiolabeling and in vivo targeting evaluation

BACKGROUND

In this study, a combination of nanotechnology, organic synthesis and radiochemistry were utilized in order to design an efficient nano-system conjugated with a suitable radionuclide and an antitumor agent for possible application as tumor theragnostic agent.

METHOD

Four novel compounds (3 and 4a-c) bearing tetrahydroquinazoline-7-sulfonohydrazide or 1,2,3,4-tetrahydroquinazoline-7-sulfonamide scaffold were designed. Then, docking study predicted that the compounds can be considered as potential inhibitors for PARP-1. Following that; the four compounds were synthesized and properly characterized using 1HNMR, 13CNMR, IR and Mass spectroscopy. The cytotoxic effect of the four compounds was evaluated against breast cancer cell line (MDA-MB-436), where compound 3 showed the most promising cytotoxic effect. The inhibitory effect of the four compounds was evaluated in vitro against PARP-1.

RESULT

Carboxylated graphene oxide nanosheets (NGO-COOH) were synthesized by a modified Hummer's method and has size of range 40 nm. The NGO-COOH nanosheets were proven to be safe and biocompatible when tested in vitro against normal human lung fibroblast cells (MRC-5). The prepared NGO-COOH nanosheets were conjugated with compound 3 then radiolabeled with 99mTc to yield 99mTc-NGO-COOH-3 with a radiochemical yield of 98.5.0 ± 0.5%. 99mTc-NGO-COOH-3 was injected intravenously in solid tumor bearing mice to study the degree of localization of the nano-system at tumor tissue. The results of the study revealed, excellent localization and retention of the designed nano-system at tumor tissues with targeting ratio of 9.0.

CONCLUSION

Stirred a new candidate tumor theragnostic agent that is safe, selective and stable.

Nanoparticles labeled with gamma-emitting radioisotopes: an attractive approach for in vivo tracking using SPECT imaging

Providing accurate molecular imaging of the body and biological process is critical for diagnosing disease and personalizing treatment with the minimum side effects. Recently, diagnostic radiopharmaceuticals have gained more attention in precise molecular imaging due to their high sensitivity and appropriate tissue penetration depth. The fate of these radiopharmaceuticals throughout the body can be traced using nuclear imaging systems, including single-photon emission computed tomography (SPECT) and positron emission tomography (PET) modalities. In this regard, nanoparticles are attractive platforms for delivering radionuclides into targets because they can directly interfere with the cell membranes and subcellular organelles. Moreover, applying radiolabeled nanomaterials can decrease their toxicity concerns because radiopharmaceuticals are usually administrated at low doses. Therefore, incorporating gamma-emitting radionuclides into nanomaterials can provide imaging probes with valuable additional properties compared to the other carriers. Herein, we aim to review (1) the gamma-emitting radionuclides used for labeling different nanomaterials, (2) the approaches and conditions adopted for their radiolabeling, and (3) their application. This study can help researchers to compare different radiolabeling methods in terms of stability and efficiency and choose the best way for each nanosystem.

Methods for Radiolabelling Nanoparticles: SPECT Use (Part 1)

The use of nanoparticles (NPs) is rapidly increasing in nuclear medicine (NM) for diagnostic and therapeutic purposes. Their wide use is due to their chemical–physical characteristics and possibility to deliver several molecules. NPs can be synthetised by organic and/or inorganic materials and they can have different size, shape, chemical composition, and charge. These factors influence their biodistribution, clearance, and targeting ability in vivo. NPs can be designed to encapsulate inside the core or bind to the surface several molecules, including radionuclides, for different clinical applications. Either diagnostic or therapeutic radioactive NPs can be synthetised, making a so-called theragnostic tool. To date, there are several methods for radiolabelling NPs that vary depending on both the physical and chemical properties of the NPs and on the isotope used. In this review, we analysed and compared different methods for radiolabelling NPs for single-photon emission computed tomography (SPECT) use.

Recent Progress in Technetium-99m-Labeled Nanoparticles for Molecular Imaging and Cancer Therapy

Nanotechnology has played a tremendous role in molecular imaging and cancer therapy. Over the last decade, scientists have worked exceptionally to translate nanomedicine into clinical practice. However, although several nanoparticle-based drugs are now clinically available, there is still a vast difference between preclinical products and clinically approved drugs. An efficient translation of preclinical results to clinical settings requires several critical studies, including a detailed, highly sensitive, pharmacokinetics and biodistribution study, and selective and efficient drug delivery to the target organ or tissue. In this context, technetium-99m (^99mTc)-based radiolabeling of nanoparticles allows easy, economical, non-invasive, and whole-body in vivo tracking by the sensitive clinical imaging technique single-photon emission computed tomography (SPECT). Hence, a critical analysis of the radiolabeling strategies of potential drug delivery and therapeutic systems used to monitor results and therapeutic outcomes at the preclinical and clinical levels remains indispensable to provide maximum benefit to the patient. This review discusses up-to-date ^99mTc radiolabeling strategies of a variety of important inorganic and organic nanoparticles and their application to preclinical imaging studies.

The Use of Alternative Strategies for Enhanced Nanoparticle Delivery to Solid Tumors

Nanomaterial (NM) delivery to solid tumors has been the focus of intense research for over a decade. Classically, scientists have tried to improve NM delivery by employing passive or active targeting strategies, making use of the so-called enhanced permeability and retention (EPR) effect. This phenomenon is made possible due to the leaky tumor vasculature through which NMs can leave the bloodstream, traverse through the gaps in the endothelial lining of the vessels, and enter the tumor. Recent studies have shown that despite many efforts to employ the EPR effect, this process remains very poor. Furthermore, the role of the EPR effect has been called into question, where it has been suggested that NMs enter the tumor via active mechanisms and not through the endothelial gaps. In this review, we provide a short overview of the EPR and mechanisms to enhance it, after which we focus on alternative delivery strategies that do not solely rely on EPR in itself but can offer interesting pharmacological, physical, and biological solutions for enhanced delivery. We discuss the strengths and shortcomings of these different strategies and suggest combinatorial approaches as the ideal path forward.

Radiolabelling of nanomaterials for medical imaging and therapy

Nanomaterials offer unique physical, chemical and biological properties of interest for medical imaging and therapy. Over the last two decades, there has been an increasing effort to translate nanomaterial-based medicinal products (so-called nanomedicines) into clinical practice and, although multiple nanoparticle-based formulations are clinically available, there is still a disparity between the number of pre-clinical products and those that reach clinical approval. To facilitate the efficient clinical translation of nanomedicinal-drugs, it is important to study their whole-body biodistribution and pharmacokinetics from the early stages of their development. Integrating this knowledge with that of their therapeutic profile and/or toxicity should provide a powerful combination to efficiently inform nanomedicine trials and allow early selection of the most promising candidates. In this context, radiolabelling nanomaterials allows whole-body and non-invasive in vivo tracking by the sensitive clinical imaging techniques positron emission tomography (PET), and single photon emission computed tomography (SPECT). Furthermore, certain radionuclides with specific nuclear emissions can elicit therapeutic effects by themselves, leading to radionuclide-based therapy. To ensure robust information during the development of nanomaterials for PET/SPECT imaging and/or radionuclide therapy, selection of the most appropriate radiolabelling method and knowledge of its limitations are critical. Different radiolabelling strategies are available depending on the type of material, the radionuclide and/or the final application. In this review we describe the different radiolabelling strategies currently available, with a critical vision over their advantages and disadvantages. The final aim is to review the most relevant and up-to-date knowledge available in this field, and support the efficient clinical translation of future nanomedicinal products for in vivo imaging and/or therapy.

Drug Delivery Systems-Based Dendrimers and Polymer Micelles for Nuclear Diagnosis and Therapy

Polymeric nanoparticles encompass micelles and dendrimers. They are used for improving or controlling the action of the loaded therapy or imaging agent, including radionuclides. Some radionuclides possess properties appropriate for simultaneous imaging and therapy of a disease and are therefore called theranostic. The diversity in core materials and surface modification, as well as radiolabeling strategies, offers multiples possibilities for preparing polymeric nanoparticles using radionuclides. The present review describes different strategies in the preparation of such nanoparticles and their applications in nuclear nanomedicine.

99mTc Radiolabeled HA/TPGS-Based Curcumin-Loaded Nanoparticle for Breast Cancer Synergistic Theranostics: Design, in vitro and in vivo Evaluation

Background

Emerging cancer therapy requires highly sensitive diagnosis in combination with cancer-targeting therapy. In this study, a self-assembled pH-sensitive curcumin (Cur)-loaded nanoparticle of ^99mTc radiolabeled hyaluronan-cholesteryl hemisuccinate conjugates (HA-CHEMS) and D-a-tocopheryl polyethylene glycol succinate (TPGS) was prepared for breast cancer synergistic theranostics.

Materials and Methods

The synthesized amphiphilic HA-CHEMS conjugates and TPGS self-assembled into Cur-loaded nanoparticles (HA-CHEMS-Cur-TPGS NPs) in an aqueous environment. The physicochemical properties of HA-CHEMS-Cur-TPGS NPs were characterized by transmission electron microscopy (TEM) and dynamic lighter scattering (DLS). The in vitro cytotoxicity of HA-CHEMS-Cur-TPGS NPs against breast cancer cells was evaluated by using the methyl thiazolyl tetrazolium (MTT) assay. Moreover, the in vivo animal experiments of HA-CHEMS-Cur-TPGS NPs including SPECT/CT imaging biodistribution and antitumor efficiency were investigated in 4T1 tumor-bearing BALB/c mice; furthermore, pharmacokinetics were investigated in healthy mice.

Results

HA-CHEMS-Cur-TPGS NPs exhibited high curcumin loading, uniform particle size distribution, and excellent stability in vitro. In the cytotoxicity assay, HA-CHEMS-Cur-TPGS NPs showed remarkably higher cytotoxicity to 4T1 cells with an IC50 value at 38 μg/mL, compared with free curcumin (77 μg/mL). Moreover, HA-CHEMS-Cur-TPGS NPs could be effectively and stably radiolabeled with ^99mTc. The SPECT images showed that ^99mTc-HA-CHEMS-Cur-TPGS NPs could target the 4T1 tumor up to 4.85±0.24%ID/g at 4 h post-injection in BALB/c mice. More importantly, the in vivo antitumor efficacy studies showed that HA-CHEMS-Cur-TPGS NPs greatly inhibited the tumor growth without resulting in obvious toxicities to major organs.

Conclusion

The results indicated that HA-CHEMS-Cur-TPGS NPs with stable ^99mTc labeling and high curcumin-loading capacity hold great potential for breast cancer synergistic theranostics.

Nanoparticulate formulations of radiopharmaceuticals: Strategy to improve targeting and biodistribution properties

Application of nanotechnology principles in drug delivery has created opportunities for treatment of several diseases. Nanotechnology offers the advantage of overcoming the adverse biopharmaceutics or pharmacokinetic properties of drug molecules, to be determined by the transport properties of the particles themselves. Through the manipulation of size, shape, charge, and type of nanoparticle delivery system, variety of distribution profiles may be obtained. However, there still exists greater need to derive and standardize definitive structure property relationships for the distribution profiles of the delivery system. When applied to radiopharmaceuticals, the delivery systems assume greater significance. For the safety and efficacy of both diagnostics and therapeutic radiopharmaceuticals, selective localization in target tissue is even more important. At the same time, the synthesis and fabrication reactions of radiolabelled nanoparticles need to be completed in much shorter time. Moreover, the extensive understanding of the several interesting optical and magnetic properties of materials in nanoscale provides for achieving multiple objectives in nuclear medicine. This review discusses the various nanoparticle systems, which are applied for radionuclides and analyses the important bottlenecks that are required to be overcome for their more widespread clinical adaptation.

Radiolabelled Polymeric Materials for Imaging and Treatment of Cancer: Quo Vadis?

Owing to their tunable blood circulation time and suitable plasma stability, polymer-based nanomaterials hold a great potential for designing and utilising multifunctional nanocarriers for efficient imaging and effective treatment of cancer. When tagged with appropriate radionuclides, they may allow for specific detection (diagnosis) as well as the destruction of tumours (therapy) or even customization of materials, aiming to both diagnosis and therapy (theranostic approach). This review provides an overview of recent developments of radiolabelled polymeric nanomaterials (natural and synthetic polymers) for molecular imaging of cancer, specifically, applying nuclear techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). Different approaches to radiolabel polymers are evaluated from the methodical radiochemical point of view. This includes new bifunctional chelating agents (BFCAs) for radiometals as well as novel labelling methods. Special emphasis is given to eligible strategies employed to evade the mononuclear phagocytic system (MPS) in view of efficient targeting. The discussion encompasses promising strategies currently employed as well as emerging possibilities in radionuclide-based cancer therapy. Key issues involved in the clinical translation of radiolabelled polymers and future scopes of this intriguing research field are also discussed.

Preparation and 68Ga-radiolabeling of porous zirconia nanoparticle platform for PET/CT-imaging guided drug delivery

This paper describes the preparation of gallium-68 (⁶⁸Ga) isotope labeled porous zirconia (ZrO₂) nanoparticle (NP) platform of nearly 100nm diameter and its first pharmacokinetic and biodistribution evaluation accomplished with a microPET/CT (μPet/CT) imaging system. Objectives of the investigations were to provide a nanoparticle platform which can be suitable for specific delivery of various therapeutic drugs using surface attached specific molecules as triggering agents, and at the same time, suitable for positron emission tomography (PET) tracing of the prospective drug delivery process. Radiolabeling was accomplished using DOTA bifunctional chelator. DOTA was successfully adsorbed onto the surface of nanoparticles, while the ⁶⁸Ga-radiolabeling method proved to be simple and effective. In the course of biodistribution studies, the ⁶⁸Ga-labeled DOTA-ZrNPs showed proper radiolabeling stability in their original suspension and in blood serum. μPet/CT imaging studies confirmed a RES-biodistribution profile indicating stable nano-sized labeled particles in vivo. Results proved that the new method offers the opportunity to examine further specifically targeted and drug payload carrier variants of zirconia NP systems using PET/CT imaging.

Image-Guided Drug Delivery with Single-Photon Emission Computed Tomography: A Review of Literature

Tremendous resources are being invested all over the world for prevention, diagnosis, and treatment of various types of cancer. Successful cancer management depends on accurate diagnosis of the disease along with precise therapeutic protocol. The conventional systemic drug delivery approaches generally cannot completely remove the competent cancer cells without surpassing the toxicity limits to normal tissues. Therefore, development of efficient drug delivery systems holds prime importance in medicine and healthcare. Also, molecular imaging can play an increasingly important and revolutionizing role in disease management. Synergistic use of molecular imaging and targeted drug delivery approaches provides unique opportunities in a relatively new area called 'image-guided drug delivery' (IGDD). Single-photon emission computed tomography (SPECT) is the most widely used nuclear imaging modality in clinical context and is increasingly being used to guide targeted therapeutics. The innovations in material science have fueled the development of efficient drug carriers based on, polymers, liposomes, micelles, dendrimers, microparticles, nanoparticles, etc. Efficient utilization of these drug carriers along with SPECT imaging technology have the potential to transform patient care by personalizing therapy to the individual patient, lessening the invasiveness of conventional treatment procedures and rapidly monitoring the therapeutic efficacy. SPECT-IGDD is not only effective for the treatment of cancer but might also find utility in the management of several other diseases. Herein, we provide a concise overview of the latest advances in SPECT-IGDD procedures and discuss the challenges and opportunities for advancement of the field.

Methods of Monitoring Cell Fate and Tissue Growth in Three-Dimensional Scaffold-Based Strategies for In Vitro Tissue Engineering

In the field of tissue engineering, there is a need for methods that allow assessing the performance of tissue-engineered constructs noninvasively in vitro and in vivo. To date, histological analysis is the golden standard to retrieve information on tissue growth, cellular distribution, and cell fate on tissue-engineered constructs after in vitro cell culture or on explanted specimens after in vivo applications. Yet, many advances have been made to optimize imaging techniques for monitoring tissue-engineered constructs with a sub-mm or μm resolution. Many imaging modalities have first been developed for clinical applications, in which a high penetration depth has been often more important than lateral resolution. In this study, we have reviewed the current state of the art in several imaging approaches that have shown to be promising in monitoring cell fate and tissue growth upon in vitro culture. Depending on the aimed tissue type and scaffold properties, some imaging methods are more applicable than others. Optical methods are mostly suited for transparent materials such as hydrogels, whereas magnetic resonance-based methods are mostly applied to obtain contrast between hard and soft tissues regardless of their transparency. Overall, this review shows that the field of imaging in scaffold-based tissue engineering is developing at a fast pace and has the potential to overcome the limitations of destructive endpoint analysis.

Silica@zirconia@poly(malic acid) nanoparticles: promising nanocarriers for theranostic applications

Nanocarriers designed, synthesized and characterized for the targeted delivery of diagnostic and therapeutic ^99mTc to folate-overexpressing tumors.

Development of Biocompatible and Functional Polymeric Nanoparticles for Site-Specific Delivery of Radionuclides

INTRODUCTION

Encapsulation of biologically active molecules into nanoparticles (NPs), for site-specific delivery, is a fast growing area. These NPs must be biocompatible, non-toxic, and able to release their load in a controlled way. We have developed a series of NPs based on (bio)degradable and biocompatible poly(malic acid) derivatives, poly(benzyl malate) (PMLABe), with its PEG-grafted stealth analog and target-specific biotin-PEG-b-PMLABe one. A lipophilic radiotracer has then been encapsulated into these NPs.

METHODS

Monomers were synthesized from dl-aspartic acid. PEG42-b-PMLABe73 and Biot-PEG66-b-PMLABe73 block copolymers were obtained by anionic ring-opening polymerization of benzyl malolactonate in presence of α-methoxy-ω-carboxy-PEG42 and α-biotin-ω-carboxy-PEG66 as initiators. NPs were prepared by nanoprecipitation. Size, polydispersity, and zeta potential were measured by dynamic light scattering (DLS) and zetametry. (99m)Tc-SSS was prepared as previously described. Encapsulation efficacy was assessed by varying different parameters, such as encapsulation with preformed NPs or during their formation, influence of the solvent, and of the method to prepare the NPs. After decay, (99m)Tc-loaded NPs were also analyzed by DLS and zetametry. NPs' morphology was assessed by transmission electron microscopy.

RESULTS

(99m)Tc-SSS was added during nanoprecipitation, using two different methods, to ensure good encapsulation. Radiolabeled NPs present increased diameters, with identical low polydispersity indexes and negative zeta potentials in comparison to non-radiolabeled NPs.

CONCLUSION

A radiotracer was successfully encapsulated, but some further optimization is still needed. The next step will be to modify these radiolabeled NPs with a hepatotrope peptide, and to replace (99m)Tc with (188)Re for therapy. Our team is also working on drugs' encapsulation and grafting of a fluorescent probe. Combining these modalities is of interest for combined chemo-/radiotherapy, bimodal imaging, and/or theranostic approach.

Visualisation of dual radiolabelled poly(lactide-co-glycolide) nanoparticle degradation in vivo using energy-discriminant SPECT

The determination of nanoparticle (NP) stability and degradation in vivo is essential for the accurate evaluation of NP biodistribution in medical applications and for understanding their toxicological effects. Such determination is particularly challenging because NPs are extremely difficult to detect and quantify once distributed in a biological system. Radiolabelling with positron or gamma emitters and subsequent imaging studies using positron emission tomography (PET) or single-photon emission computerised tomography (SPECT) are some of the few valid alternatives. However, NPs that degrade or radionuclides that detach or are released from the NPs can cause artefact. Here, submicron-sized poly(lactide-co-glycolide) nanoparticles (PLGA-NPs) stabilised with bovine serum albumin (BSA) were dual radiolabelled using gamma emitters with different energy spectra incorporated into the core and coating. To label the core, ¹¹¹In-doped iron oxide NPs were encapsulated inside PLGA-NPs during NP preparation, and the BSA coating was labelled by electrophilic substitution using ¹²⁵I. After intravenous administration into rats, energy-discriminant SPECT resolved each radioisotope independently. Imaging revealed different fates for the core and coating, with a fraction of the two radionuclides co-localising in the liver and lungs for long periods of time after administration, suggesting that NPs are stable in these organs. Organ harvesting followed by gamma counting corroborated the SPECT results. The general methodology reported here represents an excellent alternative for visualising the degradation process of multi-labelled NPs in vivo and can be extended to a wide range of engineered NPs.

Inherently fluorescent and porous zirconia colloids: preparation, characterization and drug adsorption studies

Adsorption of drug molecules onto the zirconia surface.

Recent advances in nanoparticle-based nuclear imaging of cancers

Nuclear imaging techniques that include positron emission tomography (PET) and single-photon computed tomography have found great success in the clinic because of their inherent high sensitivity. Radionuclide imaging is the most popular form of imaging to be used for molecular imaging in oncology. While many types of molecules have been used for radionuclide-based molecular imaging, there has been a great interest in developing newer nanomaterials for use in clinic, especially for cancer diagnosis and treatment. Nanomaterials have unique physical properties which allow them to be used as imaging probes to locate and identify cancerous lesions. Over the past decade, a great number of nanoparticles have been developed for radionuclide imaging of cancer. This chapter reviews the different kinds of nanomaterials, both organic and inorganic, which are currently being researched for as potential agents for nuclear imaging of variety of cancers. Several radiolabeled multifunctional nanocarriers have been extremely successful for the detection of cancer in preclinical models. So far, significant progress has been achieved in nanoparticle structure design, in vitro/in vivo trafficking, and in vivo fate mapping by using PET. There is a great need for the development of newer nanoparticles, which improve active targeting and quantify new biomarkers for early disease detection and possible prevention of cancer.