ANSTO :: Browsing by Author "Pellegrini, PA"

Browsing by Author "Pellegrini, PA"

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Alternative chromatographic processes for no-carrier added 177Lu radioisotope separation Part I. Multi-column chromatographic process for clinically applicable
(Springer, 2008-09-01) Le, VS; Morcos, N; Zaw, M; Pellegrini, PA; Greguric, I
The conventional multi-column solid phase extraction (SPE) chromatography technique using di-(2-ethylhexyl)orthophosphoric acid (HDEHP) impregnated OASIS-HLB sorbent based SPE resins (OASIS-HDEHP) was developed for the separation of no-carrier added (n.c.a) Lu-177 from the bulk quantity of ytterbium target. This technique exploited the large variation of lutetium metal ion distribution coefficients in the varying acidity of the HCl solution-OASIS-HDEHP resin systems for the consecutive loading-eluting cycles performed on different columns. The production batches of several hundred mCi n.c.a Lu-177 radioisotope separated from 50 mg Yb target activated in a nuclear reactor of medium neutron nux (Phi = 5 center dot 10(13) n.cm(-2).s(-1)) were successfully performed using the above mentioned separation technique. With the target irradiation in a reactor of thermal neutron flux Phi = 2 center dot 10(14) n.cm(-2).s(-1) or the parallel run of several separation units, many Ci-s of n.c.a Lu-177 can be profitably produced. The OASIS-HDEHP resin based multi-column SPE chromatography technique makes the separation process simple and economic and offers an automation capability for operation in highly radioactive hazardous environments. © 2008, Springer.
Alternative chromatographic processes for no-carrier added 177Lu radioisotope separation Part II. The conventional column chromatographic separation combined with HPLC for high purity
(Springer, 2008-09-01) Van So, L; Morcos, N; Zaw, M; Pellegrini, PA; Greguric, I; Nevissi, A
HPLC technique combined with the simple conventional column solid phase extraction (SPE) chromatography using di-(2- ethylhexyl)orthophosphoric acid (HDEHP) impregnated OASIS-HLB sorbent based SPE resins (OASIS-HDEHP ) was developed for the separation of no-carrier added (n.c.a) 177Lu from the bulk quantity of ytterbium target. This combination strategy was based on combining the advantages of the better resolution of HPLC separation of n.c.a 177Lu from the few milligram level Yb target with the high capacity of the OASISHDEHP column for the separation of 177Lu from the bulk Yb target. The production batches of several hundred mCi activity of n.c.a 177Lu radioisotope separated from 50 mg Yb target activated in a nuclear reactor of medium neutron flux (Φ = 5.1013 n.cm–2.s–1) were successfully performed using this combined separation technique. With the target irradiation in a reactor of higher thermal neutron flux or with the parallel run of several separation units, several Ci-s of n.c.a 177Lu can be profitably produced on a commercial production basis. © 2008, Springer.
Alternative method for Cu-64 radioisotope production
(Elsevier, 2008-05-12) Le, VS; Howse, J; Zaw, M; Pellegrini, PA; Katsifis, A; Greguric, I; Weiner, R
The method for 64Cu production based on a 64Ni target using an 18 MeV proton energy beam was developed. The studies on the optimisation of targetry for the 18 MeV proton bombardments were performed in terms of the cost-effective target utilisation and purity of the 64Cu product. The thickness-specific 64Cu yield (μCi/(μA×μm)) was introduced into the optimisation calculation with respect to cost-effective target utilisation. A maximum target utilisation efficacy factor (TUE) was found for the proton energy range of 2.5–13 MeV with corresponding target thickness of 36.2 μm. With the optimised target thickness and proton energy range, the 64Ni target thickness saving of 45.6% was achieved, while the overall 64Cu yield loss is only 23.9%, compared to the use of the whole effective proton energy range of 0–18 MeV with target thickness of 66.6 μm. This optimisation has the advantage of reducing the target amount to a reasonable level, and therefore the cost of the expensive 64Ni target material. The 64Ni target electroplated on the Au–Tl multi layer coated Cu-substrate was a new and competent design for an economic production of high quality 64Cu radioisotope using an 18 MeV proton energy cyclotron or a 30 MeV cyclotron with proton beam adjustable to 18 MeV. In this design, the Au coating layer plays a role of protection of “cold” Cu leakage from the Cu substrate and Tl serves to depress the proton beam energy (from 18 MeV to the energy optimised value 13 MeV). The ion exchange chromatographic technique with a gradient elution was applied to improve the 64Cu separation with respect to reducing the processing time and control of 64Cu product quality. © 2009, Elsevier Ltd.
Developing national capability for the production and use of radiometal based radiopharmaceuticals
(John Wiley & Sons, Inc, 2013-04-11) Lengkeek, NA; Pellegrini, PA; Oehlke, E; Fraser, BH; Greguric, I
Radiometals remain key radioisotopes for radio-medicine; the mainstay diagnostic medical imaging isotope, 99mTc, and important radioisotopes for radiotherapy, 90Y and 153Sm. However, the worldwide growth in PET centres, driven by the wildly successful [18F]-FDG, has provided a yet to be seized opportunity to deliver radiometal-based radiopharmaceuticals with clinical relevance to researchers. An ever growing set of radiometals is becoming available in Australia covering a wide range of half-lives, nuclear and chemical properties, these include 64Cu, 68Ga, 86Y, 89Zr, and looking into the near future, 44Sc, 45Ti and 90Nb. ANSTO's Lifesciences division is working to provide the Australian academic and clinical communities access to the following key areas. Radioisotope supply Two in-house 68Ge/68Ga generators; one solely for research and a larger generator for pre-clinical trials, provide access to this key radioisotope. ANSTO has provided financial and technical support to numerous cyclotron centres around Australia for development of solid targetry facilities, ensuring supply of 124I, 64Cu, 86Y and 89Zr in the short-term and 44Sc, 45Ti and 90Nb later. In coming years the OPAL reactor will begin producing pharmaceutical grade 177Lu as part of the Australian government's investment in nuclear medicine. Radiometal Labelling Research and Development In addition to our programs developing new ligands, tracers and improved radiometal labelling procedures, Lifesciences is supporting the development of new biomolecule treatments by providing researchers access to laboratories, procedures and expertise tailored specifically for functionalising biomolecules for radiometal labelling. Preclinical Radiometal Tracer Development We are working to deliver novel radiometal-based diagnostic tracers to the Australian research and clinical community by accessing the pre-clinical programs of our key international partnerships at Memorial Sloan Kettering Cancer Centre and Massachusetts General Hospital. Our initial objective is to supply the antibodies, i.e. [ 89 Zr]-J591. As our supply radiometals is diversified we will expand into proteins, peptides and other biomolecules. © 2013 John Wiley & Sons, Inc.
Development and validation of competition binding assays for affinity to the extracellular matrix receptors, αvβ3 and αIIbβ3 integrin
(Elsevier B.V., 2012-04-01) Szabo, A; Howell, NR; Pellegrini, PA; Greguric, I; Katsifis, A
The RGD (Arg-Gly-Asp) binding integrins αvβ3 and αIIbβ3 are integral components of various pathological and physiological processes, including tumor angiogenesis, osteoclast function, and thrombus formation. Because of this, there is interest in identifying novel compounds and proteins binding to these receptors as well as investigating the mechanism of these interactions. In this article, we describe the development and validation of competition binding assays for determining the affinity of test compounds to αvβ3 and αIIbβ3 integrin. Assays were successfully developed for each receptor, and the affinity of known compounds was comparable to published results. However, the inability of binding between αIIbβ3 integrin and the labeled echistatin protein ligand to reach equilibrium resulted in an assay that did not meet the assumptions of the competition binding model. Nevertheless, there was good agreement between this assay and known literature values, and intra- and interassay variability was acceptable. Binding by conformation-specific antibodies provided evidence that solid-phase bound αIIbβ3 receptor was in an activated conformation. This study also demonstrated that current models and methods for determining receptor affinity are simplistic and fail to account for common receptor–ligand interactions such as nondissociable interactions and varying receptor activation states. © 2012 by Elsevier Inc.
Development of 68Ga generator at ANSTO
(Medknow Publications, 2011-06-23) Le, VS; Izard, M; Pellegrini, PA; Zaw, M
A 68 Ge/ 68 Ga generator combined with automated 68 Ga eluate purification unit was developed to produce 68 Ga solution suitable for labelling peptide ligands for PET radiopharmaceutical applications. The sorbent of a Ti-Zr ceramic structure [1] was used as a generator column packing material. 68 Ga eluate of around 5 mL volume in 0.1 M HCl solution was purified on a small cation exchanger column with an aqueous alcohol solution mixture of hydrochloric acid, ascorbic acids and halide salts. An alkali solution was used for elution of 68 Ga from the ion exchange resin column to obtain a purified 68 Ga solution which is conditioned with acidic solutions to obtain a final 68 Ga product of pH=3-4 in 0.75 mL 0.5 M NaCl or 0.5 M sodium acetate solution. The organic solvent free 68 Ga solution product of acidity suitable for coordination chemistry based labelling of the peptide ligands was successfully used for preparation of DOTATATE and DOTATOC PET radiopharmaceuticals. The process of 68 Ga elution from the generator followed by 68 Ga eluate purification was performed using a low-cost automation bench-top system. [2] This system is designed based on the timing sequence of seven processing steps without feedback control. The variable flow rate of eluents used for elution/purification in this system also ensure the optimisation of operating times with respect to different adsorption/ desorption kinetics of 68 Ga ion species, which is controlled by the sorbent and ion exchange resin used in the generator and purification columns. © 2011, Medknow publication
Influence of metal ions on the Ga-68-labeling of dotatate
(Elsevier, 2013-12-01) Oehlke, E; Le, VS; Lengkeek, NA; Pellegrini, PA; Jackson, TW; Greguric, I; Weiner, R
The influence of metal cations (Fe3+, Fe2+, In3+, Cu2+, Ca2+, Al3+, Co2+, Lu3+, Ni2+, Pb2+, Ti4+, Y3+, Yb3+, Zn2+, and Zr4+) on the radiolabeling yield of [68Ga(DOTATATE)] was evaluated. Our most important observation was that, within our experimental limit, the metal ion/ligand ratio plays a critical role on the influence of most metal ions. More in-depth studies, with Cu2+ and Fe3+, revealed that reaction temperature and concentration changes have little effect, but speciation changes with pH are crucial. Furthermore, we found that [68Ga(DOTATATE)] is stable in the presence of high concentrations of Fe3+, Zn2+ and Pb2+, but transmetalates with Cu2+ at 95 °C. © 2013, Elsevier Ltd.
Polymeric titanium oxychloride sorbent for 188W/188Re nuclide pair separation
(Taylor & Francis, 2009-01) Le, VS; Nguyen, CD; Pellegrini, PA; Bui, VC
The chemical synthesis conditions (TiCl4: iPrOH reagent ratio and reaction temperature scheme) were optimized for the preparation of polymeric titanium oxychloride sorbent which met the requirements for clinically useful 188W/188Re generator production, such as high W-adsorption capacity, high 188Re-elution yield, low 188W-breakthrough, and good mechanical stability. This polymeric material was formed by polycondensation of titanium-oxychloride units, the chemical formula of which was supposed as [OTiO (Ti40 Cl80 (OH) 80 (TiO2)95.60H2O) OTiO]n. The effect of the W-content of tungstate solution on the WO42- ion adsorption (with minimizing the poly-tungstate ion adsorption) and its covalent bonding with the Ti metal atoms in the polymeric matrix were justified with respect to the optimal W-adsorption conditions for the preparation of a useful 188W/188Re generator column. The high W-adsorption capacity of about 515.6 mg W/g sorbent and 188Re elution yield of higher than 85% wereachieved. The large difference in the distribution ratio values found for alumina and polymeric titanium oxychloride sorbent in 0.005% NaCl solution (DW,Re-188 = 50 and DW, Re-188 = 1.0, respectively) offered an advantage for the preparation of a consecutive-elution based 188Re generator system which combined both 188Re elution and 188Re concentrating processes in one portable system. This generator system is of a tandem column type which consists of a polymeric titanium oxychloride sorbent coupled to an alumina column. This system gave a 188Re concentration factor of approximately 10. The overall 188Re yield achieved from this system was >80%. 188W isotope and elemental tungsten breakthrough were not detected in its 188Re eluate. This system thus offers a potential application for clinically useful 188Re production using low specific radioactivity 188W (around 500 mCi/g) producible in a medium neutron flux reactor. © 2009, Taylor & Francis Ltd.
Radiochemical separation and quality assessment for the 68Zn target based 64Cu radioisotope production
(Springer, 2008-08-01) Le, VS; Pellegrini, PA; Katsifis, A; Howse, J; Greguric, I
The radiochemical separation of the different radionuclides (64Cu, 67Cu, 67Ga, 66Ga, 56Ni, 57Ni, 55Co, 56Co, 57Co, 65Zn, 196Au ) induced in the Ni supported Cu substrate – 68Zn target system, which was bombarded with the 29.0 MeV proton beam, was performed by ion-exchange chromatography using successive isocratic and/or concentration gradient elution techniques. The overlapped gamma-ray spectrum analysis method was developed to assess the 67Ga and 67Cu content in the 64Cu product and even in the post-67Ga production 68Zn target solution without the support of radiochemical separation. This method was used for the assessment of 64+67Cu radioisotope separation from 67Ga , the quality control of 64Cu product and the determination of the 68Zn (p,2p)67Cu reaction yield. The improvement in the targetry and the optimization of proton beam energy for the 68Zn target based 64Cu and 67Ga production were proposed based on the stopping power and range of the incident proton and on the excitation functions, reaction yields and different radionuclides induced in the target system. © 2008, Springer.
Rhenium and technetium tricarbonyl complexes of N-Heterocyclic carbene ligands
(American Chemical Society, 2014-10-03) Chan, CY; Pellegrini, PA; Greguric, I; Barnard, PJ
A strategy for the conjugation of N-heterocyclic carbene (NHC) ligands to biomolecules via amide bond formation is described. Both 1-(2-pyridyl)imidazolium or 1-(2-pyridyl)benzimidazolium salts functionalized with a pendant carboxylic acid group were prepared and coupled to glycine benzyl ester using 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide. A series of 10 rhenium(I) tricarbonyl complexes of the form [ReX(CO)3(ĈN)] (ĈN is a bidentate NHC ligand, and X is a monodentate anionic ligand: Cl–, RCO2–) were synthesized via a Ag2O transmetalation protocol from the Re(I) precursor compound Re(CO)5Cl. The synthesized azolium salts and Re(I) complexes were characterized by elemental analysis and by 1H and 13C NMR spectroscopy, and the molecular structures for one imidazolium salt and seven Re(I) complexes were determined by single-crystal X-ray diffraction. 1H NMR and mass spectrometry studies for an acetonitrile-d3 solution of [ReCl(CO)3(1-(2-pyridyl)-3-methylimidazolylidene)] show that the monodentate chloride ligand is labile and exchanges with this solvent yielding a cationic acetonitrile adduct. For the first time the labeling of an NHC ligand with technetium-99m is reported. Rapid Tc-99m labeling was achieved by heating the imidazolium salt 1-(2-pyridyl)-3-methylimidazolium iodide and Ag2O in methanol, followed by the addition of fac-[99mTc(OH2)3(CO)3]+. To confirm the structure of the 99mTc-labeled complex, the equivalent 99Tc complex was prepared, and mass spectrometric studies showed that the formed Tc complexes are of the form [99m/99Tc(CH3CN)(CO)3(1-(2-pyridyl)-3-methylimidazolylidene)]+ with an acetonitrile molecule coordinated to the metal center. © 2014 American Chemical Society
The role of additives in moderating the influence of Fe(III) and Cu(II) on the radiochemical yield of [68Ga(DOTATATE)]
(Elsevier B.V., 2016-01) Oehlke, E; Lengkeek, AL; Le, VS; Pellegrini, PA; Greguric, I; Weiner, R
68Ga(DOTATATE)] has demonstrated its clinical usefulness. Both Fe3+ and Cu2+, potential contaminants in Gallium-68 generator eluent, substantially reduce the radiochemical (RC) yield of [68Ga(DOTATATE)] if the metal/ligand ratio of 1:1 is exceeded. A variety of compounds were examined for their potential ability to reduce this effect. Most had no effect on RC yield. However, addition of phosphate diminished the influence of Fe3+ by likely forming an insoluble iron salt. Addition of ascorbic acid reduced Cu2+ and Fe3+ to Cu+ and Fe2+ respectively, both of which have limited impact on RC yields. At low ligand amounts (5 nmol DOTATATE), the addition of 30 nmol phosphate (0.19 mM) increased the tolerance of Fe3+ from 4 nmol to 10 nmol (0.06 mM), while the addition of ascorbic acid allowed high RC yields (>95%) in the presence of 40 nmol Fe3+ (0.25 mM) and 100 nmol Cu2+ (0.63 mM). The effect of ascorbic acid was highly pH-dependant, and gave optimal results at pH 3. © 2015 Elsevier B.V.
SP-103 - Scandium-47 and lutetium-177 radiolabelling and stability studies of 1st and 2nd generation DOTA-triphenylphosphonium ligands – potential radionuclide theranostics for treatment of glioblastoma multi-forme
(Elsevier, 2021-05-17) Wyatt, NA; Hogan, L; Pellegrini, PA; Roberts, MP; Hall, A; Smith, N; Hemzal, E; Hill, L; Howell, NR; Middleton, RJ; Safavi-Naeini, M; Rendina, LM; Fraser, BH
Scandium-47 has emerged as a promising radioisotope for targeted radionuclide tumor therapy. This is due, to a significant extent, from the combination of low energy / short range β- emission, the availability of a “perfect theranostic pair” with Sc-44 for companion PET imaging, the potential to form highly stable radiometal complexes, and the availability of suitable γ emissions for companion SPECT imaging. Sc-47 also has a shorter half-life (3.35 d) than the chemically similar Lu-177 (6.7 d) which is significant given recent in vitro research that suggests longer lived isotopes require more initial radioactivity to have the same effect upon cell viability [3]. The shorter half-life of Sc-47 also suggests it may be more suitable for smaller biological vectors (with shorter biological half-lives) such as small molecules and low MW peptides. One area of clinical treatment where Sc-47 can have impact and where improvements in patient outcomes and survival rates remain stubbornly low is glioblastoma multiforme (GBM). GBM is the most common and aggressive form of malignant brain tumor and represents around 60% of all adult brain tumors with a global incidence of <10 per 100,000 persons. The prognosis for GBM patients is poor with a -ear survival rate of 37%, 5 year rate of 5% and a median survival time of 10 months. The current standard of treatment is resection of the tumor followed by radiation therapy and chemotherapy. Given this poor prognosis there is a clear and unmet need for improved classes of treatment. Although significant progress has been made towards bringing GBM targeted radionuclide therapies to the clinic, the efforts to date have not included utilizing Sc-44/ Sc-47. Given this we are developing and evaluating Sc-44/Sc-47 and Lu-177/Ga-68 radiolabelled triphenylphosphonium (TPP) functionalised DOTA ligands (1st and 2nd generation) as potential theranostics for GBM. Described herein is our work on comparing the radiolabelling efficiency (Sc-47 vs. Lu-177) and stability studies (PBS pH 7.4, rat plasma) for our 1st and 2nd generation DOTA-TPP ligands. The presence of an additional carbonyl group in the 2nd generation DOTATPP ligand was anticipated to increase the number of donor atoms around the radiometal and affect radiolabelling reaction conditions and, more importantly, increase radiometal complex stability. Copyright © 2021 Elsevier Inc.
Synthesis and in vivo biological evaluation of 68Ga labelled carbonic anhydrase IX targeting small molecules for positron emission tomography
(American Chemical Society, 2016-06-20) Sneddon, D; Niemans, R; Bauwens, M; Yaromina, A; van Kuijk, SJA; Lieuwes, NG; Biemans, R; Pooters, I; Pellegrini, PA; Lengkeek, NA; Greguric, I; Tonissen, KR; Supuran, CT; Lambin, P; Dubois, L; Poulsen, S
Tumor hypoxia contributes resistance to chemo- and radiotherapy, while oxygenated tumors are sensitive to these treatments. The indirect detection of hypoxic tumors is possible by targeting carbonic anhydrase IX (CA IX), an enzyme overexpressed in hypoxic tumors, with sulfonamide-based imaging agents. In this study, we present the design and synthesis of novel gallium-radiolabeled small-molecule sulfonamides targeting CA IX. The compounds display favorable in vivo pharmacokinetics and stability. We demonstrate that our lead compound, [68Ga]-2, discriminates CA IX-expressing tumors in vivo in a mouse xenograft model using positron emission tomography (PET). This compound shows specific tumor accumulation and low uptake in blood and clears intact to the urine. These findings were reproduced in a second study using PET/computed tomography. Small molecules investigated to date utilizing 68Ga for preclinical CA IX imaging are scarce, and this is one of the first effective 68Ga compounds reported for PET imaging of CA IX. © 2016 American Chemical Society
Synthesis and radiolabelling of DOTA-linked glutamine analogues with 67,68Ga as markers for increased glutamine metabolism in tumour cells
(MDPI (Multidisciplinary Digital Publishing Institute), 2013-06-19) Pellegrini, PA; Howell, NR; Shepherd, R; Lengkeek, NA; Oehlke, E; Katsifis, A; Greguric, I
DOTA-linked glutamine analogues with a C6- alkyl and polyethyleneglycol (PEG) chain between the chelating group and the l-glutamine moiety were synthesised and labelled with 67,68Ga using established methods. High yields were achieved for the radiolabelling of the molecules with both radionuclides (>90%), although conversion of the commercially available 67Ga-citrate to the chloride species was a requirement for consistent high radiochemical yields. The generator produced 68Ga was in the [68Ga(OH)4]− form. The 67Ga complexes and the 67Ga complexes were demonstrated to be stable in PBS buffer for a week. Uptake studies were performed with longer lived 67Ga analogues against four tumour cell lines, as well as uptake inhibition studies against l-glutamine, and two known amino acid transporter inhibitors. Marginal uptake was exhibited in the PEG variant radio-complex, and inhibition studies indicate this uptake is via a non-targeted amino acid pathway. © 2013 by the authors
Triamidetriamine bearing macrobicyclic and macrotricyclic ligands: potential applications in the development of copper-64 radiopharmaceuticals
(American Chemical Society, 2013-12-16) Tan, KV; Pellegrini, PA; Skelton, BW; Hogan, CF; Greguric, I; Barnard, PJ
A versatile and straightforward synthetic approach is described for the preparation of triamide bearing analogues of sarcophagine hexaazamacrobicyclic cage ligands without the need for a templating metal ion. Reaction of 1,1,1-tris(aminoethyl)ethane (tame) with 3 equiv of 2-chloroacetyl chloride, yields the tris(α-chloroamide) synthetic intermediate 6, which when treated with either 1,1,1-tris(aminoethyl)ethane or 1,4,7-triazacyclononane furnished two novel triamidetriamine cryptand ligands (7 and 8 respectively). The Co(III) and Cu(II) complexes of cryptand 7 were prepared; however, cryptand 8 could not be metalated. The cryptands and the Co(III) complex 9 have been characterized by elemental analysis, 1H and 13C NMR spectroscopy, and X-ray crystallography. These studies confirm that the Co(III) complex 9 adopts an octahedral geometry with three facial deprotonated amido-donors and three facial amine donor groups. The Cu(II) complex 10 was characterized by elemental analysis, single crystal X-ray crystallography, cyclic voltammetry, and UV–visible absorption spectroscopy. In contrast to the Co(III) complex (9), the Cu(II) center adopts a square planar coordination geometry, with two amine and two deprotonated amido donor groups. Compound 10 exhibited a quasi-reversible, one-electron oxidation, which is assigned to the Cu2+/3+ redox couple. These cryptands represent interesting ligands for radiopharmaceutical applications, and 7 has been labeled with 64Cu to give 64Cu-10. This complex showed good stability when subjected to l-cysteine challenge whereas low levels of decomplexation were evident in the presence of l-histidine. © 2013 American Chemical Society
Tunable and noncytotoxic PET/SPECT-MRI multimodality imaging probes using colloidally stable ligand-free superparamagnetic iron oxide nanoparticles
(Dove Press Ltd, 2017-01-27) Pham, THN; Lengkeek, NA; Greguric, I; Kim, BJ; Pellegrini, PA; Bickley, SA; Tanudji, MR; Jones, SK; Hawkett, BS; Pham, BTT
Physiologically stable multimodality imaging probes for positron emission tomography/single-photon emission computed tomography (PET/SPECT)-magnetic resonance imaging (MRI) were synthesized using the superparamagnetic maghemite iron oxide (γ-Fe2O3) nanoparticles (SPIONs). The SPIONs were sterically stabilized with a finely tuned mixture of diblock copolymers with either methoxypolyethylene glycol (MPEG) or primary amine NH2 end groups. The radioisotope for PET or SPECT imaging was incorporated with the SPIONs at high temperature. 57Co2+ ions with a long half-life of 270.9 days were used as a model for the radiotracer to study the kinetics of radiolabeling, characterization, and the stability of the radiolabeled SPIONs. Radioactive 67Ga3+ and Cu2+-labeled SPIONs were also produced successfully using the optimized conditions from the 57Co2+-labeling process. No free radioisotopes were detected in the aqueous phase for the radiolabeled SPIONs 1 week after dispersion in phosphate-buffered saline (PBS). All labeled SPIONs were not only well dispersed and stable under physiological conditions but also noncytotoxic in vitro. The ability to design and produce physiologically stable radiolabeled magnetic nanoparticles with a finely controlled number of functionalizable end groups on the SPIONs enables the generation of a desirable and biologically compatible multimodality PET/SPECT-MRI agent on a single T2 contrast MRI probe. © 2017 Dove Press Ltd under Creative Commons v3.0, BY, NC.

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