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Summary: Radiopharmaceutical research and bioscience or medical applications have changed during the decades in the function of available technologies for radioisotope production and imaging detection technologies. In the 1940s to 1960s year, radioisotopes were supplied by reactor production, such as 131I for thyroid uptake study, 197Hg, 203Hg-chlormerodrin for brain scans, 198Au-colloid for liver scans, and 85Sr-chloride for the bone scans. In the late 1960s, with the development of the gamma camera by Hal Anger, and the 99Mo/99mTc generators by researchers of the Brookhaven National Laboratory, the focus was moved to research and diagnostic application of 99mTc radiopharmaceuticals, and these compounds have been in use until now. In that age, the chemistry of technetium, including the production of different chelators and radiolabeling processes, were developed. Cyclotron-producing radioisotopes for medical application emerged in 1955, and for a long time, it was used to produce gamma-emitting radionuclides such as 67Ga, 111In, and 201Tl. After the development of PET câmera around 1975, positron-emitting radioisotopes started to be produced routinely in cyclotrons, such as 11C, 13N, and 18F, gaining market status for diagnostic applications after Alfred Wolf and colleagues developed the 18F-FDG, around 1978. In the following year, positron-emitting radiometals 68Ga, 64Cu, and 89Zr, began to be produced on a large scale to label molecules with short or long circulation times in the body. The results in the specificity of the diagnostic opened the possibility of using 90Y and 177Lu, both beta-emitting radioisotopes, to label the same molecules for therapeutic purposes; thus, theranostics pair 68Ga or 64Cu/90Y or 177Lu started to be used in nuclear medicine. From the 2010s, true theranostic pairs gain interest, such as 44gSc/47Sc, 64Cu/67Cu, 83Sr/89Sr, 86Y/90Y, 124I/131I, 152Tb/161Tb, and 152Tb/149Tb, stated to be produced and evaluated for clinical applications. All these developments in radioisotope production and imaging systems also boosted the development of molecule radiolabeling processes, mainly through automated systems, to ensure speed, reproducibility, and less exposure to professionals involved in preparing these molecules. Furthermore, several chelating agents have been developed to complex different metals in a simple, effective, and stable way, such as the DOTA, NOTA, HBED molecules, among others. Conclusão: Trends in radioisotopes and radiolabeling methods result from scientific and technological developments in different areas but with congruent purposes. The result is a large number of products that can be chosen by their physical, chemical, biological, or economic characteristics.

Recent years have witnessed increasing advances in gold nanoparticles (GNPs) for accurate and precise diagnosis and therapy. GNPs have great potential in translating into clinical nanomaterial-based products, predominantly attributed to their physicochemical and biological properties. Radiolabeling endows GNPs with high-sensitive imaging capacities in addition to providing potent therapeutic effects, which makes the development of radiolabeling nanotechnology highly desirable. In this review, we briefly describe the physicochemical properties of GNPs and radionuclides, then summarized radiolabeling methods utilized in radiolabeling GNPs, and discuss their whole-body pharmacokinetics and biodistribution. Finally, their current applications in clinical and molecular imaging and therapy are introduced. [ABSTRACT FROM AUTHOR]

Radiolabeled metal‐based nanoparticles (MNPs) have drawn considerable attention in the fields of nuclear medicine and molecular imaging, drug delivery, and radiation therapy, given the fact that they can be potentially used as diagnostic imaging and/or therapeutic agents, or even as theranostic combinations. Here, we present a systematic review on recent advances in the design and synthesis of MNPs with major focuses on their radiolabeling strategies and the determinants of their in vivo pharmacokinetics, and together how their intended applications would be impacted. For clarification, we categorize all reported radiolabeling strategies for MNPs into indirect and direct approaches. While indirect labeling simply refers to the use of bifunctional chelators or prosthetic groups conjugated to MNPs for post‐synthesis labeling with radionuclides, we found that many practical direct labeling methodologies have been developed to incorporate radionuclides into the MNP core without using extra reagents, including chemisorption, radiochemical doping, hadronic bombardment, encapsulation, and isotope or cation exchange. From the perspective of practical use, a few relevant examples are presented and discussed in terms of their pros and cons. We further reviewed the determinants of in vivo pharmacokinetic parameters of MNPs, including factors influencing their in vivo absorption, distribution, metabolism, and elimination, and discussed the challenges and opportunities in the development of radiolabeled MNPs for in vivo biomedical applications. Taken together, we believe the cumulative advancement summarized in this review would provide a general guidance in the field for design and synthesis of radiolabeled MNPs towards practical realization of their much desired theranostic capabilities. This article is categorized under:Nanotechnology Approaches to Biology > Nanoscale Systems in BiologyDiagnostic Tools > Diagnostic NanodevicesTherapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease [ABSTRACT FROM AUTHOR]

Abstract: We have developed a highly efficient method for the radiolabeling of phytantriol (PHYT)/oleic acid (OA)-based hexosomes based on the surface chelation of technetium-99m (99mTc) to preformed hexosomes using the polyamine 1, 12-diamino-3, 6, 9-triazododecane (SpmTrien) as chelating agent. We also report on the unsuccessful labeling of cubosomes using the well-known chelating agent hexamethylpropyleneamine oxime (HMPAO). The 99mTc-labeled SpmTrien-hexosomes (99mTc-SpmTrien-hexosomes) were synthesized with good radiolabeling (84%) and high radiochemical purity (>90%). The effect of radiolabeling on the internal nanostructure and the overall size of these aqueous dispersions was investigated by using synchrotron small angle X-ray scattering (SAXS), dynamic light scattering (DLS), and transmission electron cryo microscopy (cryo-TEM). Further, we show the utility of 99mTc-SpmTrien-hexosomes for the in vivo imaging of healthy mice using single photon emission computed tomography (SPECT) in combination with computed tomography (CT), i.e. SPECT/CT. SPECT/CT experiments of subcutaneously administered 99mTc-SpmTrien-hexosomes to the flank of mice showed a high stability in vivo allowing imaging of the distribution of the radiolabeled hexosomes for up to 24 h. These injected 99mTc-SpmTrien-hexosomes formed a deposit within the subcutaneous adipose tissue, displaying a high biodistribution of ∼343% injected dose/g tissue (%ID/g), with negligible uptake in other organs and tissues. The developed 99mTc labeling method for PHYT/OA-based hexosomes could further serve as a useful tool for investigating and imaging the in vivo performance of cubosomal and hexosomal drug nanocarriers. [Copyright &y& Elsevier]

Radiolabeled metal-based nanoparticles (MNPs) have drawn considerable attention in the fields of nuclear medicine and molecular imaging, drug delivery, and radiation therapy, given the fact that they can be potentially used as diagnostic imaging and/or therapeutic agents, or even as theranostic combinations. Here, we present a systematic review on recent advances in the design and synthesis of MNPs with major focuses on their radiolabeling strategies and the determinants of their in vivo pharmacokinetics, and together how their intended applications would be impacted. For clarification, we categorize all reported radiolabeling strategies for MNPs into indirect and direct approaches. While indirect labeling simply refers to the use of bifunctional chelators or prosthetic groups conjugated to MNPs for post-synthesis labeling with radionuclides, we found that many practical direct labeling methodologies have been developed to incorporate radionuclides into the MNP core without using extra reagents, including chemisorption, radiochemical doping, hadronic bombardment, encapsulation, and isotope or cation exchange. From the perspective of practical use, a few relevant examples are presented and discussed in terms of their pros and cons. We further reviewed the determinants of in vivo pharmacokinetic parameters of MNPs, including factors influencing their in vivo absorption, distribution, metabolism, and elimination, and discussed the challenges and opportunities in the development of radiolabeled MNPs for in vivo biomedical applications. Taken together, we believe the cumulative advancement summarized in this review would provide a general guidance in the field for design and synthesis of radiolabeled MNPs towards practical realization of their much desired theranostic capabilities. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease., (© 2020 Wiley Periodicals LLC.)