{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T05:05:32Z","timestamp":1792040732706,"version":"4.4.0"},"reference-count":37,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2025,8,29]],"date-time":"2025-08-29T00:00:00Z","timestamp":1756425600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"European Union Next Generation EU","award":["BG-RRP-2.004-0008"],"award-info":[{"award-number":["BG-RRP-2.004-0008"]}]},{"name":"Austrian Science Fund (FWF)","award":["BG-RRP-2.004-0008"],"award-info":[{"award-number":["BG-RRP-2.004-0008"]}]},{"name":"University of Vienna","award":["BG-RRP-2.004-0008"],"award-info":[{"award-number":["BG-RRP-2.004-0008"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Iron(III) (Fe(III)) complexes have recently emerged as safer alternatives to magnetic resonance imaging (MRI) contrast agents (CAs), reigniting interest in biomedical research. Although gadolinium Gd(III)-based contrast agents (CAs) have been widely used in MRI over the past four decades, their use in the current clinical routine is severely constrained due to concerns about high toxicity and environmental impact. Research is now focusing on synthesizing safer contrast agents with alternative paramagnetic ions like Fe(III) or Mn(II). MRI CAs with integrated potent therapeutic moieties may offer synergistic advantages over traditional contrast agents in clinical use. The study explored the use of salinomycin-ferrihydrite composites as possible effective ensembles of imaging and therapeutic units in the same molecule, evaluating their anticancer activity and influence on the signal in MRI. The composites were characterized using M\u00f6ssbauer spectroscopy and ICP-MS for iron content determination. The in vitro relaxivity measurements in a high-field MR scanner demonstrated the potency of the composites as T2 enhancers. The antitumor activity of one selected Sal-ferrihydrite composite was tested in three human cancer cell lines: A549 (non-small cell lung cancer); SW480 (colon cancer); and CH1\/PA1 (ovarian teratocarcinoma) by the MTT cell viability assay. The new Sal-ferrihydrite composite showed a pronounced cytotoxicity in all three human cancers in line with enhanced signal in MRI, which makes it a promising candidate for future biomedical applications. The superior cytotoxic effect, together with the strong signal enhancement, makes these compounds promising candidates for further detailed investigations as future theranostic agents.<\/jats:p>","DOI":"10.3390\/ijms26178405","type":"journal-article","created":{"date-parts":[[2025,8,29]],"date-time":"2025-08-29T16:42:21Z","timestamp":1756485741000},"page":"8405","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["First In Vitro Characterization of Salinomycinic Acid-Containing Two-Line Ferrihydrite Composites with Pronounced Antitumor Activity as MRI Contrast Agents"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0312-6461","authenticated-orcid":false,"given":"Irena","family":"Pashkunova-Martic","sequence":"first","affiliation":[{"name":"Preclinical Imaging Laboratory, Department of Biomedical Imaging and Image-Guided Therapy, Division of Molecular and Structural Preclinical Imaging, Medical University of Vienna & General Hospital of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria"},{"name":"Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Strasse 42, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1830-8113","authenticated-orcid":false,"given":"Joachim","family":"Friske","sequence":"additional","affiliation":[{"name":"Preclinical Imaging Laboratory, Department of Biomedical Imaging and Image-Guided Therapy, Division of Molecular and Structural Preclinical Imaging, Medical University of Vienna & General Hospital of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniela","family":"Paneva","sequence":"additional","affiliation":[{"name":"Institute of Catalysis, Bulgarian Academy of Sciences, Acad. 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Georgi Bonchev Str., Bldg. 11, 1113 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michaela","family":"Hejl","sequence":"additional","affiliation":[{"name":"Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Strasse 42, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7945-1426","authenticated-orcid":false,"given":"Michael","family":"Jakupec","sequence":"additional","affiliation":[{"name":"Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Strasse 42, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0975-9051","authenticated-orcid":false,"given":"Simone","family":"Braeuer","sequence":"additional","affiliation":[{"name":"Institute of Analytical Chemistry, Department of Natural Sciences and Sustainable Resources, BOKU University, Muthgasse 18, 1190 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4173-548X","authenticated-orcid":false,"given":"Peter","family":"Dorkov","sequence":"additional","affiliation":[{"name":"Research and Development Department, Biovet Ltd., 4550 Peshtera, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bernhard K.","family":"Keppler","sequence":"additional","affiliation":[{"name":"Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Strasse 42, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thomas H.","family":"Helbich","sequence":"additional","affiliation":[{"name":"Preclinical Imaging Laboratory, Department of Biomedical Imaging and Image-Guided Therapy, Division of Molecular and Structural Preclinical Imaging, Medical University of Vienna & General Hospital of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3213-2046","authenticated-orcid":false,"given":"Juliana","family":"Ivanova","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Sofia University \u201cSt. Kliment Ohridski\u201d, Kozjak Str., 1, 1407 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1633","DOI":"10.1039\/D2QI02665A","article-title":"A systematic investigation of the NMR relaxation properties of Fe(III)-EDTA derivatives and their potential as MRI contrast agents","volume":"10","author":"Nucera","year":"2023","journal-title":"Inorg. 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