1
|
Shaw MA, Poncelet M, Viswakarma N, Vallerini GP, Hameed S, Gluth TD, Geldenhuys WJ, Hoblitzell EH, Eubank TD, Epel B, Kotecha M, Driesschaert B. SOX71, A Biocompatible Succinyl Derivative of the Triarylmethyl Radical OX071 for In Vivo Quantitative Oxygen Mapping Using Electron Paramagnetic Resonance. Mol Imaging Biol 2024; 26:542-552. [PMID: 37945971 PMCID: PMC11078887 DOI: 10.1007/s11307-023-01869-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/27/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023]
Abstract
PURPOSE This study aimed to develop a biocompatible oximetric electron paramagnetic resonance (EPR) spin probe with reduced self-relaxation, and sensitivity to oxygen for a higher signal-to-noise ratio and longer relaxation times at high oxygen concentration, compared to the reference spin probe OX071. PROCEDURES SOX71 was synthesized by succinylation of the twelve alcohol groups of OX071 spin probe and characterized by EPR at X-Band (9.5 GHz) and at low field (720 MHz). The biocompatibility of SOX71 was tested in vitro and in vivo in mice. A pharmacokinetic study was performed to determine the best time frame for EPR imaging. Finally, a proof-of-concept EPR oxygen imaging was performed on a mouse model of a fibrosarcoma tumor. RESULTS SOX71 was synthesized in one step from OX071. SOX71 exhibits a narrow line EPR spectrum with a peak-to-peak linewidth of 66 mG, similar to OX071. SOX71 does not bind to albumin nor show cell toxicity for the concentrations tested up to 5 mM. No toxicity was observed after systemic delivery via intraperitoneal injection in mice at twice the dose required for EPR imaging. After the injection, the probe is readily absorbed into the bloodstream, with a peak blood concentration half an hour, post-injection. Then, the probe is quickly cleared by the kidney with a half-life of ~ 45 min. SOX71 shows long relaxation times under anoxic condition (T1e = 9.5 µs and T2e = 5.1 µs; [SOX71] = 1 mM in PBS at 37 °C, pO2 = 0 mmHg, 720 MHz). Both the relaxation rates R1e and R2e show a decreased sensitivity to pO2, leading to twice longer relaxation times under room air conditions (pO2 = 159 mmHg) compared to OX071. This is ideal for oxygen imaging in samples with a wide range of pO2. Both the relaxation rates R1e and R2e show a decreased sensitivity to self-relaxation compared to OX071, with a negligible effect of the probe concentration on R1e. SOX71 was successfully applied to image oxygen in a tumor. CONCLUSION SOX71, a succinylated derivative of OX071 was synthesized, characterized, and applied for in vivo EPR tumor oxygen imaging. SOX71 is highly biocompatible, and shows decreased sensitivity to oxygen and self-relaxation. This first report suggests that SOX71 is superior to OX071 for absolute oxygen mapping under a broad range of pO2 values.
Collapse
Affiliation(s)
- Misa A Shaw
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV, 26506, USA
- In Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA
- West Virginia Clinical and Translational Sciences Institute, Morgantown, WV, 26506, USA
| | - Martin Poncelet
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV, 26506, USA
- In Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA
| | - Navin Viswakarma
- Oxygen Measurement Core, O2M Technologies, LLC, Chicago, IL, 60612, USA
| | | | - Safa Hameed
- Oxygen Measurement Core, O2M Technologies, LLC, Chicago, IL, 60612, USA
| | - Teresa D Gluth
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV, 26506, USA
- In Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA
| | - Werner J Geldenhuys
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV, 26506, USA
- Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA
| | - Emily H Hoblitzell
- Department of Microbiology, Immunology, and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV, 26506, USA
| | - Timothy D Eubank
- In Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA
- West Virginia Clinical and Translational Sciences Institute, Morgantown, WV, 26506, USA
- Department of Microbiology, Immunology, and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV, 26506, USA
- West Virginia University Cancer Institute, West Virginia University, Morgantown, WV, 26506, USA
| | - Boris Epel
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL, 60637, USA
| | - Mrignayani Kotecha
- Oxygen Measurement Core, O2M Technologies, LLC, Chicago, IL, 60612, USA.
| | - Benoit Driesschaert
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV, 26506, USA.
- In Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA.
- West Virginia Clinical and Translational Sciences Institute, Morgantown, WV, 26506, USA.
- Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA.
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL, 60637, USA.
| |
Collapse
|
2
|
Moore W, Huffman JL, Driesschaert B, Eaton SS, Eaton GR. Impact of Chlorine Substitution on Electron Spin Relaxation of a Trityl Radical. APPLIED MAGNETIC RESONANCE 2022; 53:797-808. [PMID: 35601029 PMCID: PMC9122340 DOI: 10.1007/s00723-021-01405-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
A perchlorotriarylmethyl tricarboxylic acid radical 99% enriched in 13C at the central carbon (13C1-PTMTC) was characterized in phosphate buffered saline solution (pH = 7.2) (PBS) at ambient temperature. Samples immobilized in 1:1 PBS:glycerol or in 9:1 trehalose:sucrose were studied as a function of temperature. Isotope enrichment at C1 creates a trityl that can be used to accurately measure microscopic viscosity. Understanding of the impact of the 13C hyperfine interaction on electron spin relaxation is important for application of this trityl in oximetry and distance measurements. The anisotropic 13C1 hyperfine couplings (Ax = Ay = 24 ± 2 MHz, Az = 200 ± 1 MHz) are larger than for the related 13C1-perdeuterated Finland trityl (13C1-dFT) and the g anisotropy (gx = 2.0013, gy = 2.0016, gz = 2.0042) is slightly larger than for 13C1-dFT. The tumbling correlation times (τR) for 13C1-PTMTC are 0.20 ± 0.02 ns in PBS and 0.40 ± 0.05 ns in 3:1 PBS:glycerol, which are shorter than for 13C1-dFT in the same solutions. T1 for 13C1-PTMTC is 3.5 ± 0.5 μs in PBS and 5.3 ± 0.4 μs in 3:1 PBS:glycerol, which are shorter than for 13C1-dFT due to faster tumbling, larger anisotropy of the 13C1 hyperfine, and about 30% larger contribution from the local mode. In immobilized samples T1 for 13C1-PTMTC is similar to that for 13C1-dFT and other trityls without chlorine or 13C1 substituents, indicating that the 13C1 and Cl substituents on the phenyl rings have little impact on T1. The temperature dependence of T1 was modeled with contributions from the direct, Raman, and local mode processes. Broadening of CW linewidths of about 0.6 G in fluid solution and about 2 G in rigid lattice is attributed to unresolved 35,37Cl hyperfine couplings.
Collapse
Affiliation(s)
- Whylder Moore
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Justin L. Huffman
- Department of Pharmaceutical Sciences, School of Pharmacy & In Vivo Multifunctional Magnetic Resonance Center, West Virginia University, Morgantown, WV 26506, USA
| | - Benoit Driesschaert
- Department of Pharmaceutical Sciences, School of Pharmacy & In Vivo Multifunctional Magnetic Resonance Center, West Virginia University, Morgantown, WV 26506, USA
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| |
Collapse
|
3
|
Moore W, McPeak JE, Poncelet M, Driesschaert B, Eaton SS, Eaton GR. 13C isotope enrichment of the central trityl carbon decreases fluid solution electron spin relaxation times. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 318:106797. [PMID: 32769018 PMCID: PMC7492462 DOI: 10.1016/j.jmr.2020.106797] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 05/19/2023]
Abstract
Electron spin relaxation times for perdeuterated Finland trityl 99% enriched in 13C at the central carbon (13C1-dFT) were measured in phosphate buffered saline (pH = 7.2) (PBS) solution at X-band. The anisotropic 13C1 hyperfine (Ax = Ay = 18 ± 2, Az = 162 ± 1 MHz) and g values (2.0033, 2.0032, 2.00275) in a 9:1 trehalose:sucrose glass at 293 K and in 1:1 PBS:glycerol at 160 K were determined by simulation of spectra at X-band and Q-band. In PBS at room temperature the tumbling correlation time, τR, is 0.29 ± 0.02 ns. The linewidths are broadened by incomplete motional averaging of the hyperfine anisotropy and T2 is 0.13 ± 0.02 µs, which is shorter than the T2 ~ 3.8 µs for natural abundance dFT at low concentration in PBS. T1 for 13C1-dFT in deoxygenated PBS is 5.9 ± 0.5 µs, which is shorter than for natural abundance dFT in PBS (16 µs) but much longer than in air-saturated solution (0.48 ± 0.04 µs). The tumbling dependence of T1 in PBS, 3:1 PBS:glycerol (τR = 0.80 ± 0.05 ns, T1 = 9.7 ± 0.7 µs) and 1:1 PBS:glycerol (τR = 3.4 ± 0.3 ns, T1 = 12.0 ± 1.0 µs) was modeled with contributions to the relaxation predominantly from modulation of hyperfine anisotropy and a local mode. The 1/T1 rate for the 1% 12C1-dFT in the predominantly 13C labeled sample is about a factor of 6 more strongly concentration dependent than for natural abundance 12C1-trityl, which reflects the importance of Heisenberg exchange with molecules with different resonance frequencies and faster relaxation rates. In glassy matrices at 160 K, T1 and Tm for 13C1-dFT are in good agreement with previously reported values for 12C1-dFT consistent with the expectation that modulation of nuclear hyperfine does not contribute to electron spin relaxation in a rigid lattice.
Collapse
Affiliation(s)
- Whylder Moore
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Joseph E McPeak
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Martin Poncelet
- Department of Pharmaceutical Sciences, School of Pharmacy & In Vivo Multifunctional Magnetic Resonance Center, West Virginia University, Morgantown, WV 26506, USA
| | - Benoit Driesschaert
- Department of Pharmaceutical Sciences, School of Pharmacy & In Vivo Multifunctional Magnetic Resonance Center, West Virginia University, Morgantown, WV 26506, USA
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA.
| |
Collapse
|
4
|
Chen NT, Barth ED, Lee TH, Chen CT, Epel B, Halpern HJ, Lo LW. Highly sensitive electron paramagnetic resonance nanoradicals for quantitative intracellular tumor oxymetric images. Int J Nanomedicine 2019; 14:2963-2971. [PMID: 31118615 PMCID: PMC6503311 DOI: 10.2147/ijn.s194779] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 03/11/2019] [Indexed: 01/25/2023] Open
Abstract
Purpose: Tumor oxygenation is a critical parameter influencing the efficacy of cancer therapy. Low levels of oxygen in solid tumor have been recognized as an indicator of malignant progression and metastasis, as well as poor response to chemo- and radiation therapy. Being able to measure oxygenation for an individual's tumor would provide doctors with a valuable way of identifying optimal treatments for patients. Methods: Electron paramagnetic resonance imaging (EPRI) in combination with an oxygen-measuring paramagnetic probe was performed to measure tumor oxygenation in vivo. Triarylmethyl (trityl) radical exhibits high specificity, sensitivity, and resolution for quantitative measurement of O2 concentration. However, its in vivo applications in previous studies have been limited by the required high dosage, its short half-life, and poor intracellular permeability. To address these limitations, we developed high-capacity nanoformulated radicals that employed fluorescein isothiocyanate-labeled mesoporous silica nanoparticles (FMSNs) as trityl radical carriers. The high surface area nanostructure and easy surface modification of physiochemical properties of FMSNs enable efficient targeted delivery of highly concentrated, nonself-quenched trityl radicals, protected from environmental degradation and dilution. Results: We successfully designed and synthesized a tumor-targeted nanoplatform as a carrier for trityl. In addition, the nanoformulated trityl does not affect oxygen-sensing capacity by a self-relaxation or broadening effect. The FMSN-trityl exhibited high sensitivity/response to oxygen in the partial oxygen pressure range from 0 to 155 mmHg. Furthermore, MSN-trityl displayed outstanding intracellular oxygen mapping in both in vitro and in vivo animal studies. Conclusion: The highly sensitive nanoformulated trityl spin probe can profile intracellular oxygen distributions of tumor in a real-time and quantitative manner using in vivo EPRI.
Collapse
Affiliation(s)
- Nai-Tzu Chen
- Institute of New Drug Development, China Medical University, Taichung 40402, Taiwan
| | - Eugene D Barth
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.,Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA
| | - Tsung-Hsi Lee
- Department of Biological Science and Technology, China Medical University, Taichung 40402, Taiwan
| | - Chin-Tu Chen
- Department of Radiology, University of Chicago, Chicago, IL 60637 USA
| | - Boris Epel
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.,Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA
| | - Howard J Halpern
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.,Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA
| | - Leu-Wei Lo
- Department of Radiology, University of Chicago, Chicago, IL 60637 USA.,Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan 35053, Taiwan
| |
Collapse
|