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Kras EA, Cineus R, Crawley MR, Morrow JR. Macrocyclic complexes of Fe(III) with mixed hydroxypropyl and phenolate or amide pendants as T 1 MRI probes. Dalton Trans 2024; 53:4154-4164. [PMID: 38318938 PMCID: PMC10897765 DOI: 10.1039/d3dt04013e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 01/29/2024] [Indexed: 02/07/2024]
Abstract
High-spin Fe(III) complexes of 1,4,7-triazacyclononane (TACN) with mixed oxygen donor pendants including hydroxypropyl, phenolate or amide groups are prepared for study as T1 MRI probes. Complexes with two hydroxypropyl pendants and either amide (Fe(TOAB)) or phenolate (Fe(PTOB)) groups are compared to an analog with three hydroxypropyl groups (Fe(NOHP)), in order to study the effect of the third pendant on the coordination sphere as probed by solution chemistry, relaxivity and structural studies. Solution studies show that Fe(PTOB) has two ionizations with the phenol pendant deprotonating with a pKa of 1.7 and a hydroxypropyl pendent with pKa of 6.3. The X-ray crystal structure of [Fe(PTOB)]Br2 features a six-coordinate complex with two bound hydroxypropyl groups, and a phenolate in a distorted octahedral geometry. The Fe(TOAB) complex has a single deprotonation, assigned to a hydroxypropyl group with a pKa value of 7.0. Both complexes are stabilized as high-spin Fe(III) in solution as shown by their effective magnetic moments and Fe(III)/Fe(II) redox potentials of -390 mV and -780 mV versus NHE at pH 7 and 25 °C for Fe(TOAB) and Fe(PTOB) respectively. Both Fe(PTOB) and Fe(TOAB) are kinetically inert to dissociation under a variety of challenges including phosphate/carbonate buffer, one equivalent of ZnCl2, two equivalents of transferrin or 100 mM HCl, or at basic pH values over 24 h at 37 °C. The r1 relaxivity of Fe(TOAB) at 1.4 T, pH 7.4 and 33 °C is relatively low at 0.6 mM-1 s-1 whereas the r1 relaxivity of Fe(PTOB) is more substantial and shows an increase of 2.5 fold to 2.5 mM-1 s-1 at acidic pH. The increase in relaxivity at acidic pH is attributed to protonation of the phenolate group to provide an additional pathway for proton relaxation.
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Affiliation(s)
- Elizabeth A Kras
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, NY 14260, USA.
| | - Roy Cineus
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, NY 14260, USA.
| | - Matthew R Crawley
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, NY 14260, USA.
| | - Janet R Morrow
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, NY 14260, USA.
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Chowdhury MSI, Kras EA, Turowski SG, Spernyak JA, Morrow JR. Liposomal MRI probes containing encapsulated or amphiphilic Fe(III) coordination complexes. Biomater Sci 2023; 11:5942-5954. [PMID: 37470467 DOI: 10.1039/d3bm00029j] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
Liposomes containing high-spin Fe(III) coordination complexes were prepared towards the production of T1 MRI probes with improved relaxivity. The amphiphilic Fe(III) complexes were anchored into the liposome with two alkyl chains to give a coordination sphere containing mixed amide and hydroxypropyl pendant groups. The encapsulated complex contains a macrocyclic ligand with three phosphonate pendants, [Fe(NOTP)]3-, which was chosen for its good aqueous solubility. Four types of MRI probes were prepared including those with intraliposomal Fe(III) complex (LipoA) alone, amphiphilic Fe(III) complex (LipoB), both intraliposomal and amphiphilic complex (LipoC) or micelles formed with amphiphilic complex. Water proton relaxivities r1 and r2 were measured and compared to a small molecule macrocyclic Fe(III) complex containing similar donor groups. Micelles of the amphiphilic Fe(III) complex had proton relaxivity values (r1 = 2.6 mM-1 s-1) that were four times higher than the small hydrophilic analog. Liposomes with amphiphilic Fe(III) complex (LipoB) have a per iron relaxivity of 2.6 mM-1 s-1 at pH 7.2, 34 °C at 1.4 T whereas liposomes containing both amphiphilic and intraliposomal Fe(III) complexes (lipoC) have r1 of 0.58 mM-1 s-1 on a per iron basis consistent with quenching of the interior Fe(III) complex relaxivity. Liposomes containing only encapsulated [Fe(NOTP)]3- have a lowered r1 of 0.65 mM-1 s-1 per iron complex. Studies show that the biodistribution and clearance of the different types liposomal nanoparticles differ greatly. LipoB is a blood pool agent with a long circulation time whereas lipoC is cleared more rapidly through both renal and hepatobiliary pathways. These clearance differences are consistent with lower stability of LipoC compared to LipoB.
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Affiliation(s)
- Md Saiful I Chowdhury
- Department of Chemistry, University at Buffalo, The State University of New York, Amherst, NY 14260, USA.
| | - Elizabeth A Kras
- Department of Chemistry, University at Buffalo, The State University of New York, Amherst, NY 14260, USA.
| | - Steven G Turowski
- Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, Buffalo, New York 14263, USA
| | - Joseph A Spernyak
- Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, Buffalo, New York 14263, USA
| | - Janet R Morrow
- Department of Chemistry, University at Buffalo, The State University of New York, Amherst, NY 14260, USA.
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Hu P, Mo H, Song S, Wu J, Li J, Shen J. An iron(III) complex-based supramolecular organic framework (SOF) as a theranostic platform via magnetic resonance imaging-guided chemotherapy. J Mater Chem B 2023; 11:4799-4807. [PMID: 37194355 DOI: 10.1039/d2tb02551e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
It is crucially important to explore the additional metal-endowed functions of supramolecular organic frameworks (SOFs) for expanding their applications. In this work we have reported the performance of a SOF (designated as Fe(III)-SOF) as a theranostic platform via magnetic resonance imaging (MRI)-guided chemotherapy. The Fe(III)-SOF may be used as an MRI contrast agent for cancer diagnosis because the building unit (iron complex) contains high spin iron(III) ions. Additionally, the Fe(III)-SOF may also be used as a drug carrier because it possesses stable internal voids. We loaded doxorubicin (DOX) into the Fe(III)-SOF to obtain a DOX@Fe(III)-SOF. The Fe(III)-SOF showed good loading content (16.3%) and high loading efficiency (65.2%) for DOX. Additionally, the DOX@Fe(III)-SOF had a relatively modest relaxivity value (r2 = 19.745 mM-1 s-1) and exhibited the strongest negative contrast (darkest) at 12 h of post-injection. Furthermore, the DOX@Fe(III)-SOF effectively inhibited tumor growth and showed high anticancer efficiency. In addition, the Fe(III)-SOF was biocompatible and biosafe. Therefore, the Fe(III)-SOF was an excellent theranostic platform and may have potential applications in tumor diagnosis and treatment in the future. We believe that this work will initiate extensive research endeavors not only on the development of SOFs, but also on the construction of theranostic platforms based on SOFs.
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Affiliation(s)
- Pengpeng Hu
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Engineering Research Center for Biomedical Function Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.
| | - Hong Mo
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Engineering Research Center for Biomedical Function Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.
| | - Saijie Song
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Engineering Research Center for Biomedical Function Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.
| | - Jing Wu
- Nanjing Customs District Industrial Products Inspection Center, Nanjing 210019, China
| | - Jihui Li
- Shenyang Institute of Industrial Technology, Shenyang 110000, China
| | - Jian Shen
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Engineering Research Center for Biomedical Function Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.
- Jiangsu Engineering Research Center of Interfacial Chemistry, Nanjing University, Nanjing, 210023, China
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Duraiyarasu M, Kumaran SS, Mayilmurugan R. Alkyl Chain Appended Fe(III) Catecholate Complex as a Dual-Modal T1 MRI-NIR Fluorescence Imaging Agent via Second Sphere Water Interactions. ACS Biomater Sci Eng 2023. [PMID: 37141045 DOI: 10.1021/acsbiomaterials.3c00203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The C12-alkyl chain-conjugated Fe(III) catecholate complex [Fe(C12CAT)3]3-, Fe(C12CAT)3 [C12CAT = N-(3,4-dihydroxyphenethyl)dodecanamide], was synthesized and characterized, reported as a dual-modal T1-MRI and an optical imaging probe. The DFT-optimized structure of Fe(C12CAT)3 reveals a distorted octahedral coordination geometry around the high spin Fe(III) center. The formation constant (-log K) of Fe(C12CAT)3 was calculated as 45.4. The complex exhibited r1-relaxivity values of 2.31 ± 0.12 and 1.52 ± 0.06 mM-1 s-1 at 25 and 37 °C, respectively, on 1.41 T at pH 7.3 via second-sphere water interactions. The interaction of Fe(C12CAT)3 with human serum albumin showed concomitant enhancement of r1-relaxivity to 6.44 ± 0.15 mM-1 s-1. The MR phantom images are significantly brighter and directly correlate to the concentration of Fe(C12CAT)3. Adding an external fluorescent marker IR780 dye to Fe(C12CAT)3 leads to the formation of self-assembly by C12-alkyl chains. It resulted in the fluorescence quenching of the dye, and its critical aggregation concentration was calculated as 70 μM. The aggregated matrix of Fe(C12CAT)3 and IR780 dye is spherical, with an average hydrodynamic diameter of 189.5 nm. This self-assembled supramolecular system is found to be non-fluorescent and was "turn-on" under acidic pH via dissociation of aggregates. The r1-relaxivity is found to be unchanged during the matrix aggregation and disaggregation. The probe showed MRI ON and fluorescent OFF under physiological conditions and MRI ON and fluorescent ON under acidic pH. The cell viability experiments showed that the cells are 80% viable at 1 mM probe concentration. Fluorescence experiments and MR phantom images showed that Fe(C12CAT)3 is a potential dual model imaging probe to visualize the acidic pH environment of the cells.
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Affiliation(s)
- Maheshwaran Duraiyarasu
- Department of Chemistry, and Department of Bioscience & Biomedical Engineering, Indian Institute of Technology Bhilai, Raipur, Chattisgarh 492015, India
| | - S Senthil Kumaran
- Department of NMR, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029, India
| | - Ramasamy Mayilmurugan
- Department of Chemistry, and Department of Bioscience & Biomedical Engineering, Indian Institute of Technology Bhilai, Raipur, Chattisgarh 492015, India
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Morrow JR, Raymond JJ, Chowdhury MSI, Sahoo PR. Redox-Responsive MRI Probes Based on First-Row Transition-Metal Complexes. Inorg Chem 2022; 61:14487-14499. [PMID: 36067522 DOI: 10.1021/acs.inorgchem.2c02197] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The presence of multiple oxidation and spin states of first-row transition-metal complexes facilitates the development of switchable MRI probes. Redox-responsive probes capitalize on a change in the magnetic properties of the different oxidation states of the paramagnetic metal ion center upon exposure to biological oxidants and reductants. Transition-metal complexes that are useful for MRI can be categorized according to whether they accelerate water proton relaxation (T1 or T2 agents), induce paramagnetic shifts of 1H or 19F resonances (paraSHIFT agents), or are chemical exchange saturation transfer (CEST) agents. The various oxidation state couples and their properties as MRI probes are summarized with a focus on Co(II)/Co(III) or Fe(II)/Fe(III) complexes as small molecules or as liposomal agents. Solution studies of these MRI probes are reviewed with an emphasis on redox changes upon treatment with oxidants or with enzymes that are physiologically important in inflammation and disease. Finally, we outline the challenges of developing these probes further for in vivo MRI applications.
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Affiliation(s)
- Janet R Morrow
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
| | - Jaclyn J Raymond
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
| | - Md Saiful I Chowdhury
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
| | - Priya Ranjan Sahoo
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
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Kras EA, Snyder EM, Sokolow GE, Morrow JR. Distinct Coordination Chemistry of Fe(III)-Based MRI Probes. Acc Chem Res 2022; 55:1435-1444. [PMID: 35482819 DOI: 10.1021/acs.accounts.2c00102] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
ConspectusContrast agents are used in approximately 40% of all magnetic resonance imaging (MRI) procedures to improve the quality of the images based on the distribution and dynamic clearance of the agent. To date, all clinically approved contrast agents are Gd(III) coordination complexes that serve to shorten the longitudinal (T1) and transverse (T2) proton relaxation times of water. Recent interest in replacing Gd with biologically relevant metal ions such as Mn or Fe has led to increased interest in the aqueous coordination chemistry of their complexes. In this Account, we focus on high-spin Fe(III) complexes that have been recently reported as MRI contrast agents or probes in our laboratory.The highly Lewis acidic Fe(III) center has distinct coordination chemistry in aqueous solutions, facilitating alternative strategies in the design of MRI probes. To illustrate this, we describe different classes of Fe(III) MRI probes with a focus on macrocyclic complexes and multinuclear complexes such as self-assembled metal organic polyhedra (MOP). Our initial efforts focused on macrocyclic complexes of Fe(III) in order to tune spin and oxidation states with the goal of stabilizing high-spin Fe(III) in reducing biological environments. Our probes feature six-coordinate Fe(III) complexes of 1,4,7-triazacyclononane with hydroxypropyl, phosphonate, or carboxylate pendant groups to produce Fe(III) complexes that shorten proton T1 times predominantly from second-sphere or outer-sphere interactions at neutral pH. Analogues with pentadentate macrocyclic ligands have an inner-sphere water that does not exchange rapidly on the NMR time scale, yet these complexes are effective relaxation agents. Fe(III) macrocyclic complexes in this class can be modified to modulate their biodistribution and pharmacokinetic clearance in mice. The goal of these studies is for the Fe(III) agents to clear as extracellular fluid agents and produce profiles similar to those of Gd agents. Finally, studies of multimeric Fe(III) complexes are of interest to produce probes that give large proton relaxivity. In this approach the two Fe(III) centers are connected through aryl linkers as demonstrated for several macrocyclic complexes. Even more tightly connected Fe(III) centers are produced in a Fe(III) self-assembled cage with relaxivity of 21 mM-1 s-1 at 4.7 T, 37 °C in the presence of serum albumin to which it is tightly bound. This cage enhances contrast of the vasculature as a blood pool agent and accumulates in tumors. Finally, we present our perspectives on the further development of Fe(III) complexes for various applications in MRI.
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Affiliation(s)
- Elizabeth A. Kras
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
| | - Eric M. Snyder
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
| | - Gregory E. Sokolow
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
| | - Janet R. Morrow
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
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Xue SS, Pan Y, Pan W, Liu S, Li N, Tang B. Bioimaging agents based on redox-active transition metal complexes. Chem Sci 2022; 13:9468-9484. [PMID: 36091899 PMCID: PMC9400682 DOI: 10.1039/d2sc02587f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 07/27/2022] [Indexed: 11/21/2022] Open
Abstract
Detecting the fluctuation and distribution of various bioactive species in biological systems is of great importance in determining diseases at their early stages. Metal complex-based probes have attracted considerable attention in bioimaging applications owing to their unique advantages, such as high luminescence, good photostability, large Stokes shifts, low toxicity, and good biocompatibility. In this review, we summarized the development of redox-active transition metal complex-based probes in recent five years with the metal ions of iron, manganese, and copper, which play essential roles in life and can avoid the introduction of exogenous metals into biological systems. The designing principles that afford these complexes with optical or magnetic resonance (MR) imaging properties are elucidated. The applications of the complexes for bioimaging applications of different bioactive species are demonstrated. The current challenges and potential future directions of these probes for applications in biological systems are also discussed. This review summarizes transition metal complexes as bioimaging agents in optical and magnetic resonance imaging.![]()
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Affiliation(s)
- Shan-Shan Xue
- College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Centre of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University Jinan 250014 P. R. China
| | - Yingbo Pan
- College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Centre of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University Jinan 250014 P. R. China
| | - Wei Pan
- College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Centre of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University Jinan 250014 P. R. China
| | - Shujie Liu
- College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Centre of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University Jinan 250014 P. R. China
| | - Na Li
- College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Centre of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University Jinan 250014 P. R. China
| | - Bo Tang
- College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Centre of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University Jinan 250014 P. R. China
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