{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T18:26:25Z","timestamp":1787077585299,"version":"build-2736575974"},"reference-count":42,"publisher":"American Chemical Society (ACS)","issue":"19","license":[{"start":{"date-parts":[[2025,5,7]],"date-time":"2025-05-07T00:00:00Z","timestamp":1746576000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100009360","name":"King's College London","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100009360","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000266","name":"Engineering and Physical Sciences Research Council","doi-asserted-by":"publisher","award":["EP\/S032789\/1"],"award-info":[{"award-number":["EP\/S032789\/1"]}],"id":[{"id":"10.13039\/501100000266","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000272","name":"National Institute for Health and Care Research","doi-asserted-by":"publisher","award":["IS-BRC-1215-20006"],"award-info":[{"award-number":["IS-BRC-1215-20006"]}],"id":[{"id":"10.13039\/501100000272","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100013915","name":"EPSRC Centre for Doctoral Training in Medical Imaging","doi-asserted-by":"publisher","award":["EP\/L015226\/1"],"award-info":[{"award-number":["EP\/L015226\/1"]}],"id":[{"id":"10.13039\/501100013915","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100010269","name":"Wellcome Trust","doi-asserted-by":"publisher","award":["WT 203148\/Z\/16\/Z"],"award-info":[{"award-number":["WT 203148\/Z\/16\/Z"]}],"id":[{"id":"10.13039\/100010269","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,5,20]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Pretargeted PET imaging has emerged as a leading strategy for tracking long-circulating agents such as antibodies and nanoparticle-drug delivery systems with short-lived isotopes. Compared to the conventional direct radiolabeling approach, pretargeting benefits from high sensitivity and spatial resolution of PET while minimizing radiation doses and nonspecific accumulation of radioactivity. In addition, it allows for long-term in vivo tracking possibilities. However, a pretargeting approach that can utilize readily available radionuclides as obtained from the generator\/cyclotron without the need of complex radiochemical synthesis is highly desirable. Here, we report a metal chelation pretargeting system based on the 68Ga chelator tris\u00ad(hydroxypyridinone) (THP). THP can be radiolabeled at low concentrations with as-obtained generator-produced radionuclide gallium-68 (t1\/2 = 68 min) at room temperature and physiological conditions with high efficiency. The bifunctional chelator THP-NCS was conjugated to either PEGylated liposomes or a bone-targeting aminobisphosphonate (pamidronate) to examine the metal chelation pretargeted imaging system in both long-circulating nanomedicines and short-circulating small molecules, respectively. In vivo imaging experiments were performed in healthy BalB\/c mice at multiple time points. For liposomal pretargeting, the fraction of liposomes circulating in the blood was efficiently radiolabeled in vivo, but limited in vivo radiolabeling was observed for liposomes that had accumulated in the liver and spleen. The pretargeting of the small-molecule, bone-targeting bisphosphonate THP-Pam showed moderate in vivo radiolabeling in bones. Overall, based on this study, the metal chelation method appears to allow easy pretargeting for agents present in the blood and bones but with limited success in other organs.<\/jats:p>","DOI":"10.1021\/acsomega.4c10050","type":"journal-article","created":{"date-parts":[[2025,5,7]],"date-time":"2025-05-07T03:41:47Z","timestamp":1746589307000},"page":"19379-19393","source":"Crossref","is-referenced-by-count":2,"title":["Exploring In Vivo\nMetal Chelation as an Approach for\nPretargeted PET Imaging"],"prefix":"10.1021","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7055-8788","authenticated-orcid":true,"given":"Aishwarya","family":"Mishra","sequence":"first","affiliation":[{"name":"King\u2019s College London , , St Thomas\u2019 Hospital , ,","place":["London, U.K., SE1 7EH"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1501-3288","authenticated-orcid":true,"given":"George","family":"Keeling","sequence":"additional","affiliation":[{"name":"King\u2019s College London , , St Thomas\u2019 Hospital , ,","place":["London, U.K., SE1 7EH"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4386-440X","authenticated-orcid":true,"given":"Jana","family":"Kim","sequence":"additional","affiliation":[{"name":"King\u2019s College London , , St Thomas\u2019 Hospital , ,","place":["London, U.K., SE1 7EH"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0431-0535","authenticated-orcid":true,"given":"Rafael","family":"T. M. de Rosales","sequence":"additional","affiliation":[{"name":"King\u2019s College London , , St Thomas\u2019 Hospital , ,","place":["London, U.K., SE1 7EH"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2025,5,7]]},"reference":[{"issue":"5","key":"2026081811213895400_cit1","doi-asserted-by":"publisher","first-page":"3355","DOI":"10.1039\/D0CS00384K","article-title":"Radiolabelling of Nanomaterials for\nMedical Imaging and Therapy","volume":"50","author":"Pellico","year":"2021","journal-title":"Chem. Soc. Rev."},{"key":"2026081811213895400_cit2","doi-asserted-by":"publisher","first-page":"419","DOI":"10.2165\/00003088-200342050-00002","volume-title":"Pharmacokinetics of Pegylated\nLiposomal Doxorubicin: Review of Animal and Human Studies","author":"Gabizon","year":"2003"},{"issue":"8","key":"2026081811213895400_cit3","doi-asserted-by":"publisher","first-page":"986","DOI":"10.1016\/j.bmcl.2019.02.014","article-title":"Improved Radiosynthesis and Preliminary in Vivo Evaluation\nof the 11C-Labeled Tetrazine [11C]\u00adAE-1 for Pretargeted PET Imaging","volume":"29","author":"Ste\u0301en","year":"2019","journal-title":"Bioorg. Med. Chem. Lett."},{"issue":"9","key":"2026081811213895400_cit4","doi-asserted-by":"publisher","DOI":"10.1021\/acs.molpharmaceut.2c00220","article-title":"Pretargeted\nPET of Osteodestructive Lesions in Dogs","volume":"19","author":"Maitz","year":"2022","journal-title":"Mol.\nPharmaceutics"},{"issue":"20","key":"2026081811213895400_cit5","doi-asserted-by":"publisher","first-page":"9381","DOI":"10.1021\/acs.jmedchem.6b00938","article-title":"A Bone-Seeking Trans-Cyclooctene\nfor Pretargeting and Bioorthogonal Chemistry: A Proof of Concept Study\nUsing 99mTc- and 177Lu-Labeled Tetrazines","volume":"59","author":"Yazdani","year":"2016","journal-title":"J.\nMed. Chem."},{"issue":"40","key":"2026081811213895400_cit6","doi-asserted-by":"publisher","first-page":"10549","DOI":"10.1002\/anie.201304026","article-title":"Mesoporous Silica Nanoparticle Pretargeting\nfor PET\nImaging Based on a Rapid Bioorthogonal Reaction in a Living Body","volume":"52","author":"Lee","year":"2013","journal-title":"Angew. Chem., Int. Ed."},{"issue":"1","key":"2026081811213895400_cit7","doi-asserted-by":"publisher","first-page":"62","DOI":"10.1021\/acsomega.6b00269","article-title":"Pretargeted\nPET Imaging of Trans-Cyclooctene-Modified\nPorous Silicon Nanoparticles","volume":"2","author":"Keina\u0308nen","year":"2017","journal-title":"ACS Omega"},{"issue":"33","key":"2026081811213895400_cit8","doi-asserted-by":"publisher","first-page":"18082","DOI":"10.1002\/anie.202103307","article-title":"Enzyme-Mediated In Situ Self-Assembly\nPromotes In Vivo Bioorthogonal Reaction for Pretargeted Multimodality\nImaging","volume":"60","author":"Hu","year":"2021","journal-title":"Angew. Chem., Int. Ed."},{"issue":"1","key":"2026081811213895400_cit9","doi-asserted-by":"publisher","first-page":"1417","DOI":"10.1021\/acsnano.5b06860","article-title":"Pretargeted Positron Emission Tomography\nImaging That Employs Supramolecular Nanoparticles with in Vivo Bioorthogonal\nChemistry","volume":"10","author":"Hou","year":"2016","journal-title":"ACS Nano"},{"issue":"1","key":"2026081811213895400_cit10","doi-asserted-by":"publisher","first-page":"568","DOI":"10.1021\/acsnano.9b06905","article-title":"Trans-Cyclooctene-Functionalized\nPeptoBrushes with Improved Reaction Kinetics of the Tetrazine Ligation\nfor Pretargeted Nuclear Imaging","volume":"14","author":"Ste\u0301en","year":"2020","journal-title":"ACS Nano"},{"issue":"7","key":"2026081811213895400_cit11","doi-asserted-by":"publisher","first-page":"1707","DOI":"10.1021\/acs.bioconjchem.6b00234","article-title":"Design, Synthesis,\nand Evaluation of a Low-Molecular-Weight 11C-Labeled Tetrazine for\nPretargeted PET Imaging Applying Bioorthogonal in Vivo Click Chemistry","volume":"27","author":"Denk","year":"2016","journal-title":"Bioconjug Chem."},{"issue":"7","key":"2026081811213895400_cit12","doi-asserted-by":"publisher","first-page":"622","DOI":"10.1039\/D4CB00039K","article-title":"[68 Ga]\u00adGa-THP-Tetrazine\nfor Bioorthogonal Click Radiolabelling: Pretargeted PET Imaging of\nLiposomal Nanomedicines","volume":"5","author":"Mishra","year":"2024","journal-title":"RSC Chem. Biol."},{"key":"2026081811213895400_cit13","doi-asserted-by":"publisher","first-page":"209","DOI":"10.1016\/j.biomaterials.2018.06.021","article-title":"Pretargeting\nin\nNuclear Imaging and Radionuclide Therapy: Improving Efficacy of Theranostics\nand Nanomedicines","volume":"179","author":"Ste\u0301en","year":"2018","journal-title":"Biomaterials"},{"issue":"11","key":"2026081811213895400_cit14","doi-asserted-by":"publisher","first-page":"1989","DOI":"10.2967\/jnumed.113.123745","article-title":"Diels-Alder\nReaction for Tumor Pretargeting: In Vivo Chemistry Can Boost Tumor\nRadiation Dose Compared with Directly Labeled Antibody","volume":"54","author":"Rossin","year":"2013","journal-title":"J. Nucl. Med."},{"issue":"23","key":"2026081811213895400_cit15","doi-asserted-by":"publisher","first-page":"6415","DOI":"10.1039\/C5CS00784D","article-title":"New Insights\ninto the Pretargeting Approach to Image and Treat Tumours","volume":"45","author":"Patra","year":"2016","journal-title":"Chem. Soc. Rev."},{"issue":"10","key":"2026081811213895400_cit16","doi-asserted-by":"publisher","first-page":"1553","DOI":"10.2967\/jnumed.117.189944","article-title":"Pretargeted Imaging and Therapy","volume":"58","author":"Altai","year":"2017","journal-title":"J. Nucl. Med."},{"issue":"4","key":"2026081811213895400_cit17","doi-asserted-by":"publisher","DOI":"10.3390\/ijms21041496","article-title":"Manipulating the in Vivo Behaviour\nOf68ga with Tris\u00ad(Hydroxypyridinone)\nChelators: Pretargeting and Blood Clearance","volume":"21","author":"Imberti","year":"2020","journal-title":"Int. J. Mol. Sci."},{"issue":"25","key":"2026081811213895400_cit18","doi-asserted-by":"publisher","first-page":"7068","DOI":"10.1039\/c1cc12123e","article-title":"Efficient\nBifunctional Gallium-68 Chelators for Positron\nEmission Tomography: Tris\u00ad(Hydroxypyridinone) Ligands","volume":"47","author":"Berry","year":"2011","journal-title":"Chem. Commun."},{"key":"2026081811213895400_cit19","doi-asserted-by":"publisher","first-page":"4299","DOI":"10.1039\/c8dt04454f","article-title":"Tuning\nthe Properties of Tris\u00ad(Hydroxypyridinone) Ligands: Efficient 68 Ga\nChelators for PET Imaging","volume":"48","author":"Imberti","year":"2019","journal-title":"Dalton Trans."},{"issue":"4","key":"2026081811213895400_cit20","doi-asserted-by":"publisher","DOI":"10.3390\/biomedicines9040367","article-title":"Nhs-Functionalized Thp Derivative for Efficient Synthesis\nof Kit-Based Precursors For68 Ga Labeled Pet Probes","volume":"9","author":"Floresta","year":"2021","journal-title":"Biomedicines"},{"issue":"7","key":"2026081811213895400_cit21","doi-asserted-by":"publisher","first-page":"1276","DOI":"10.1021\/acs.bioconjchem.0c00401","article-title":"Ga-THP-Pam: A Bisphosphonate PET\nTracer with Facile Radiolabeling and Broad Calcium Mineral Affinity","volume":"32","author":"Keeling","year":"2021","journal-title":"Bioconjug Chem."},{"issue":"1","key":"2026081811213895400_cit22","doi-asserted-by":"publisher","DOI":"10.1186\/s13550-017-0336-6","article-title":"Simple,\nMild, One-Step Labelling of Proteins with Gallium-68\nUsing a Tris\u00ad(Hydroxypyridinone) Bifunctional Chelator: A 68Ga-THP-ScFv\nTargeting the Prostate-Specific Membrane Antigen","volume":"7","author":"Nawaz","year":"2017","journal-title":"EJNMMI Res."},{"issue":"4","key":"2026081811213895400_cit23","doi-asserted-by":"publisher","first-page":"625","DOI":"10.2967\/jnumed.117.199554","article-title":"Cold Kit for Prostate-Specific\nMembrane Antigen (PSMA) PET Imaging: Phase 1 Study of 68Ga-Tris (Hydroxypyridinone)-PSMA\nPET\/CT in Patients with Prostate Cancer","volume":"59","author":"Hofman","year":"2018","journal-title":"J.\nNucl. Med."},{"issue":"8","key":"2026081811213895400_cit24","doi-asserted-by":"publisher","first-page":"1270","DOI":"10.2967\/jnumed.117.191882","article-title":"68Ga-THP-PSMA:\nA PET Imaging Agent for Prostate Cancer Offering Rapid, Room-Temperature,\n1-Step Kit-Based RaDiolabeling","volume":"58","author":"Young","year":"2017","journal-title":"J. Nucl. Med."},{"issue":"2","key":"2026081811213895400_cit25","doi-asserted-by":"publisher","first-page":"289","DOI":"10.1021\/bc9801124","article-title":"Targeting Folate Receptor with Folate\nLinked to Extremities of Poly\u00ad(Ethylene Glycol)-Grafted Liposomes:\nIn Vitro Studies","volume":"10","author":"Gabizon","year":"1999","journal-title":"Bioconjug Chem."},{"issue":"2","key":"2026081811213895400_cit26","doi-asserted-by":"publisher","first-page":"309","DOI":"10.1021\/acs.bioconjchem.5b00335","article-title":"New Tris\u00ad(Hydroxypyridinone)\nBifunctional Chelators Containing Isothiocyanate Groups Provide a\nVersatile Platform for Rapid One-Step Labeling and PET Imaging with\n68Ga3+","volume":"27","author":"Ma","year":"2016","journal-title":"Bioconjug Chem."},{"issue":"1","key":"2026081811213895400_cit27","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-023-41149-7","article-title":"68Ga-Bisphosphonates\nfor the Imaging\nof Extraosseous Calcification by Positron Emission Tomography","volume":"13","author":"Keeling","year":"2023","journal-title":"Sci. Rep"},{"issue":"2\u20133","key":"2026081811213895400_cit28","doi-asserted-by":"publisher","first-page":"243","DOI":"10.1016\/0014-5793(96)00452-8","article-title":"Insertion of Poly\u00ad(Ethylene Glycol) Derivatized Phospholipid\ninto Pre-Formed Liposomes Results in Prolonged in Vivo Circulation\nTime","volume":"386","author":"Uster","year":"1996","journal-title":"FEBS Lett."},{"issue":"1\u20132","key":"2026081811213895400_cit29","doi-asserted-by":"publisher","first-page":"49","DOI":"10.1016\/S0168-3659(03)00295-5","article-title":"Controlled\nTargeting of Liposomal Doxorubicin via the Folate Receptor in Vitro","volume":"92","author":"Saul","year":"2003","journal-title":"J. Controlled Release"},{"issue":"2","key":"2026081811213895400_cit30","doi-asserted-by":"publisher","DOI":"10.3390\/pharmaceutics10020057","article-title":"Impact of Particle\nSize and Polydispersity Index on\nthe Clinical Applications of Lipidic Nanocarrier Systems","volume":"10","author":"Danaei","year":"2018","journal-title":"Pharmaceutics"},{"issue":"2","key":"2026081811213895400_cit31","doi-asserted-by":"publisher","first-page":"401","DOI":"10.1016\/0009-8981(72)90059-9","article-title":"The Behaviour\nof Tracer Gallium-67\ntowards Serum Proteins","volume":"39","author":"Gunasekera","year":"1972","journal-title":"Clin. Chim. Acta"},{"issue":"4","key":"2026081811213895400_cit32","doi-asserted-by":"publisher","first-page":"803","DOI":"10.1021\/bi00352a011","article-title":"Thermodynamics\nof Gallium Complexation by Human Lactoferrin","volume":"25","author":"Harris","year":"1986","journal-title":"Biochemistry"},{"issue":"12","key":"2026081811213895400_cit33","doi-asserted-by":"publisher","first-page":"1727","DOI":"10.2967\/jnumed.120.257527","article-title":"A Phase II, Open-Label\nStudy to Assess Safety and Management Change Using 68 Ga-THP PSMA\nPET\/CT in Patients with High-Risk Primary Prostate Cancer or Biochemical\nRecurrence After Radical Treatment: The PRONOUNCED Study","volume":"62","author":"Afaq","year":"2021","journal-title":"J. Nucl. Med."},{"issue":"1","key":"2026081811213895400_cit34","doi-asserted-by":"publisher","first-page":"219","DOI":"10.1016\/j.ymthe.2018.10.006","article-title":"In Vivo PET Tracking of 89 Zr-Labeled V\u03b39V\u03b42\nT Cells to Mouse Xenograft Breast Tumors Activated with Liposomal\nAlendronate","volume":"27","author":"Man","year":"2019","journal-title":"Mol. Ther."},{"issue":"9","key":"2026081811213895400_cit35","doi-asserted-by":"publisher","first-page":"3867","DOI":"10.7150\/thno.40403","article-title":"PET\nImaging of Liposomal Glucocorticoids Using 89Zr-Oxine: Theranostic\nApplications in Inflammatory Arthritis","volume":"10","author":"Gawne","year":"2020","journal-title":"Theranostics"},{"issue":"3","key":"2026081811213895400_cit36","doi-asserted-by":"publisher","first-page":"996","DOI":"10.1016\/S0022-3565(24)39325-5","article-title":"Preclinical and\nClinical Evidence for Disappearance of Long-Circulating Characteristics\nof Polyethylene Glycol Liposomes at Low Lipid Dose","volume":"293","author":"Laverman","year":"2000","journal-title":"J. Pharmacol. Exp. Ther."},{"issue":"1","key":"2026081811213895400_cit37","doi-asserted-by":"publisher","first-page":"60","DOI":"10.5507\/bp.2014.052","article-title":"Selected68Ga-Siderophores\nVersus68Ga-Colloid And68Ga-Citrate: Biodistribution and Small Animal\nImaging in Mice","volume":"159","author":"Petrik","year":"2015","journal-title":"Biomed. Pap."},{"issue":"1","key":"2026081811213895400_cit38","doi-asserted-by":"publisher","first-page":"102","DOI":"10.1007\/s11307-013-0654-7","article-title":"68Ga-Triacetylfusarinine\nC and 68Ga-Ferrioxamine\ne for Aspergillus Infection Imaging: Uptake Specificity in Various\nMicroorganisms","volume":"16","author":"Petrik","year":"2014","journal-title":"Mol. Imaging Biol."},{"issue":"1","key":"2026081811213895400_cit39","doi-asserted-by":"publisher","first-page":"71","DOI":"10.2174\/1874471011205010071","article-title":"68 Ga-Citrate-PET\nfor Diagnostic Imaging of Infection in Rats and for Intra-Abdominal\nInfection in a Patient","volume":"5","author":"Kumar","year":"2011","journal-title":"Curr. Radiopharm."},{"issue":"5","key":"2026081811213895400_cit40","doi-asserted-by":"publisher","first-page":"435","DOI":"10.1016\/0883-2897(89)90053-6","article-title":"Gallium Radiopharmaceutical\nChemistry","volume":"16","author":"Green","year":"1989","journal-title":"Int. J. Rad. Appl. Instrum. B."},{"issue":"3","key":"2026081811213895400_cit41","first-page":"282","article-title":"Gallium: Mechanisms","volume":"21","author":"Hoffer","year":"1980","journal-title":"J. Nucl. Med."},{"issue":"1","key":"2026081811213895400_cit42","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1186\/2191-219X-1-14","article-title":"Uptake of\n68gallium in Atherosclerotic Plaques in LDLR\u2013\/\u2013ApoB100\/100\nMice","volume":"1","author":"Silvola","year":"2011","journal-title":"EJNMMI Res."}],"container-title":["ACS Omega"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/acsomega.4c10050","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/10\/19\/19379\/40828365\/ao4c10050.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/10\/19\/19379\/40828365\/ao4c10050.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T17:37:52Z","timestamp":1787074672000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/acsodf\/article\/10\/19\/19379\/3654157\/Exploring-In-Vivo-Metal-Chelation-as-an-Approach"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,5,7]]},"references-count":42,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2025,5,7]]},"published-print":{"date-parts":[[2025,5,20]]}},"URL":"https:\/\/doi.org\/10.1021\/acsomega.4c10050","relation":{},"ISSN":["2470-1343"],"issn-type":[{"value":"2470-1343","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,5,7]]}}}