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Dziurman G, Drzał A, Murzyn AA, Kmiec MM, Elas M, Krzykawska-Serda M. Pulse and CW EPR Oximetry Using Oxychip in Gemcitabine-Treated Murine Pancreatic Tumors. Mol Imaging Biol 2024; 26:473-483. [PMID: 37784004 PMCID: PMC11211198 DOI: 10.1007/s11307-023-01859-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 09/14/2023] [Accepted: 09/15/2023] [Indexed: 10/04/2023]
Abstract
PURPOSE The goal of this work was to compare pO2 measured using both continuous wave (CW) and pulse electron paramagnetic resonance (EPR) spectroscopy. The Oxychip particle spin probe enabled longitudinal monitoring of pO2 in murine pancreatic tumor treated with gemcitabine during the course of therapy. PROCEDURES Pancreatic PanO2 tumors were growing in the syngeneic mice, in the leg. Five doses of saline in control animals or gemcitabine were administered every 3 days, and pO2 was measured after each dose at several time points. Oxygen partial pressure was determined from the linewidth of the CW EPR signal (Bruker E540L) or from the T2 measured using the electron spin echo sequence (Jiva-25™). RESULTS The oxygen sensitivity was determined from a calibration curve as 6.1 mG/mm Hg in CW EPR and 68.5 ms-1/mm Hg in pulse EPR. A slight increase in pO2 of up to 20 mm Hg was observed after the third dose of gemcitabine compared to the control. The maximum delta pO2 during the therapy correlated with better survival. CONCLUSIONS Both techniques offer fast and reliable oximetry in vivo, allowing to follow the effects of pharmaceutic intervention.
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Affiliation(s)
- Gabriela Dziurman
- Department of Biophysics and Cancer Biology, Faculty of Biochemistry, Biophysics and Biotechnology Jagiellonian University, 7 Gronostajowa St., 30-387, Krakow, Poland
| | - Agnieszka Drzał
- Department of Biophysics and Cancer Biology, Faculty of Biochemistry, Biophysics and Biotechnology Jagiellonian University, 7 Gronostajowa St., 30-387, Krakow, Poland
| | - Aleksandra Anna Murzyn
- Department of Biophysics and Cancer Biology, Faculty of Biochemistry, Biophysics and Biotechnology Jagiellonian University, 7 Gronostajowa St., 30-387, Krakow, Poland
| | - Maciej Mikolaj Kmiec
- Department of Radiology, Geisel School of Medicine, Dartmouth College, 1 Rope Ferry Rd, Hanover, NH, 03755, USA
| | - Martyna Elas
- Department of Biophysics and Cancer Biology, Faculty of Biochemistry, Biophysics and Biotechnology Jagiellonian University, 7 Gronostajowa St., 30-387, Krakow, Poland
| | - Martyna Krzykawska-Serda
- Department of Biophysics and Cancer Biology, Faculty of Biochemistry, Biophysics and Biotechnology Jagiellonian University, 7 Gronostajowa St., 30-387, Krakow, Poland.
- Department of Radiation & Cellular Oncology, The University of Chicago, 5758 S Maryland Ave, Chicago, IL, 60637, USA.
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Gallez B. The Role of Imaging Biomarkers to Guide Pharmacological Interventions Targeting Tumor Hypoxia. Front Pharmacol 2022; 13:853568. [PMID: 35910347 PMCID: PMC9335493 DOI: 10.3389/fphar.2022.853568] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 06/23/2022] [Indexed: 12/12/2022] Open
Abstract
Hypoxia is a common feature of solid tumors that contributes to angiogenesis, invasiveness, metastasis, altered metabolism and genomic instability. As hypoxia is a major actor in tumor progression and resistance to radiotherapy, chemotherapy and immunotherapy, multiple approaches have emerged to target tumor hypoxia. It includes among others pharmacological interventions designed to alleviate tumor hypoxia at the time of radiation therapy, prodrugs that are selectively activated in hypoxic cells or inhibitors of molecular targets involved in hypoxic cell survival (i.e., hypoxia inducible factors HIFs, PI3K/AKT/mTOR pathway, unfolded protein response). While numerous strategies were successful in pre-clinical models, their translation in the clinical practice has been disappointing so far. This therapeutic failure often results from the absence of appropriate stratification of patients that could benefit from targeted interventions. Companion diagnostics may help at different levels of the research and development, and in matching a patient to a specific intervention targeting hypoxia. In this review, we discuss the relative merits of the existing hypoxia biomarkers, their current status and the challenges for their future validation as companion diagnostics adapted to the nature of the intervention.
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Kmiec MM, Hebert KA, Tse D, Hodge S, Williams BB, Schaner PE, Kuppusamy P. OxyChip embedded with radio-opaque gold nanoparticles for anatomic registration and oximetry in tissues. Magn Reson Med 2022; 87:1621-1637. [PMID: 34719047 PMCID: PMC8776570 DOI: 10.1002/mrm.29039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/07/2021] [Accepted: 09/18/2021] [Indexed: 11/07/2022]
Abstract
PURPOSE Electron paramagnetic resonance oximetry using the OxyChip as an implantable oxygen sensor can directly and repeatedly measure tissue oxygen levels. A phase I, first-in-human clinical study has established the safety and feasibility of using OxyChip for reliable and repeated measurements of oxygen levels in a variety of tumors and treatment regimens. A limitation in these studies is the inability to easily locate and identify the implanted probes in the tissue, particularly in the long term, thus limiting spatial/anatomical registration of the implant for proper interpretation of the oxygen data. In this study, we have developed and evaluated an enhanced oxygen-sensing probe embedded with gold nanoparticles (GNP), called the OxyChip-GNP, to enable visualization of the sensor using routine clinical imaging modalities. METHODS In vitro characterization, imaging, and histopathology studies were carried out using tissue phantoms, excised tissues, and in vivo animal models (mice and rats). RESULTS The results demonstrated a substantial enhancement of ultrasound and CT contrast using the OxyChip-GNP without compromising its electron paramagnetic resonance and oxygen-sensing properties or biocompatibility. CONCLUSIONS The OxyChips embedded with gold nanoparticles (OxyChip-GNP) can be readily identified in soft tissues using standard clinical imaging modalities such as CT, cone beam-CT, or ultrasound imaging while maintaining its capability to make repeated in vivo measurements of tissue oxygen levels over the long term. This unique capability of the OxyChip-GNP facilitates precisely localized in vivo oxygen measurements in the clinical setting.
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Affiliation(s)
- Maciej M. Kmiec
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine Dartmouth College Lebanon New Hampshire USA
| | - Kendra A. Hebert
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine Dartmouth College Lebanon New Hampshire USA
| | - Dan Tse
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine Dartmouth College Lebanon New Hampshire USA
| | - Sassan Hodge
- Thayer School of Engineering Dartmouth College Hanover New Hampshire USA
| | - Benjamin B. Williams
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine Dartmouth College Lebanon New Hampshire USA
- Thayer School of Engineering Dartmouth College Hanover New Hampshire USA
- Department of Medicine Dartmouth‐Hitchcock Medical Center Lebanon New Hampshire USA
| | - Philip E. Schaner
- Department of Medicine Dartmouth‐Hitchcock Medical Center Lebanon New Hampshire USA
| | - Periannan Kuppusamy
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine Dartmouth College Lebanon New Hampshire USA
- Thayer School of Engineering Dartmouth College Hanover New Hampshire USA
- Department of Medicine Dartmouth‐Hitchcock Medical Center Lebanon New Hampshire USA
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Schaner PE, Williams BB, Chen EY, Pettus JR, Schreiber WA, Kmiec MM, Jarvis LA, Pastel DA, Zuurbier RA, DiFlorio-Alexander RM, Paydarfar JA, Gosselin BJ, Barth RJ, Rosenkranz KM, Petryakov SV, Hou H, Tse D, Pletnev A, Flood AB, Wood VA, Hebert KA, Mosher RE, Demidenko E, Swartz HM, Kuppusamy P. First-In-Human Study in Cancer Patients Establishing the Feasibility of Oxygen Measurements in Tumors Using Electron Paramagnetic Resonance With the OxyChip. Front Oncol 2021; 11:743256. [PMID: 34660306 PMCID: PMC8517507 DOI: 10.3389/fonc.2021.743256] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Accepted: 09/07/2021] [Indexed: 01/23/2023] Open
Abstract
OBJECTIVE The overall objective of this clinical study was to validate an implantable oxygen sensor, called the 'OxyChip', as a clinically feasible technology that would allow individualized tumor-oxygen assessments in cancer patients prior to and during hypoxia-modification interventions such as hyperoxygen breathing. METHODS Patients with any solid tumor at ≤3-cm depth from the skin-surface scheduled to undergo surgical resection (with or without neoadjuvant therapy) were considered eligible for the study. The OxyChip was implanted in the tumor and subsequently removed during standard-of-care surgery. Partial pressure of oxygen (pO2) at the implant location was assessed using electron paramagnetic resonance (EPR) oximetry. RESULTS Twenty-three cancer patients underwent OxyChip implantation in their tumors. Six patients received neoadjuvant therapy while the OxyChip was implanted. Median implant duration was 30 days (range 4-128 days). Forty-five successful oxygen measurements were made in 15 patients. Baseline pO2 values were variable with overall median 15.7 mmHg (range 0.6-73.1 mmHg); 33% of the values were below 10 mmHg. After hyperoxygenation, the overall median pO2 was 31.8 mmHg (range 1.5-144.6 mmHg). In 83% of the measurements, there was a statistically significant (p ≤ 0.05) response to hyperoxygenation. CONCLUSIONS Measurement of baseline pO2 and response to hyperoxygenation using EPR oximetry with the OxyChip is clinically feasible in a variety of tumor types. Tumor oxygen at baseline differed significantly among patients. Although most tumors responded to a hyperoxygenation intervention, some were non-responders. These data demonstrated the need for individualized assessment of tumor oxygenation in the context of planned hyperoxygenation interventions to optimize clinical outcomes.
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Affiliation(s)
- Philip E. Schaner
- Department of Medicine, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Benjamin B. Williams
- Department of Medicine, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Eunice Y. Chen
- Department of Surgery, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Jason R. Pettus
- Department of Pathology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Wilson A. Schreiber
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Maciej M. Kmiec
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Lesley A. Jarvis
- Department of Medicine, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - David A. Pastel
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Rebecca A. Zuurbier
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Roberta M. DiFlorio-Alexander
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Joseph A. Paydarfar
- Department of Surgery, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Benoit J. Gosselin
- Department of Surgery, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Richard J. Barth
- Department of Surgery, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Kari M. Rosenkranz
- Department of Surgery, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Sergey V. Petryakov
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Huagang Hou
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Dan Tse
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Alexandre Pletnev
- Department of Chemistry, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Ann Barry Flood
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Victoria A. Wood
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Kendra A. Hebert
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Robyn E. Mosher
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Eugene Demidenko
- Department of Biomedical Data Science, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Harold M. Swartz
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
| | - Periannan Kuppusamy
- Department of Medicine, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
- Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
- Department of Chemistry, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, and Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
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Chen EY, Tse D, Hou H, Schreiber WA, Schaner PE, Kmiec MM, Hebert KA, Kuppusamy P, Swartz HM, Williams BB. Evaluation of a Refined Implantable Resonator for Deep-Tissue EPR Oximetry in the Clinic. APPLIED MAGNETIC RESONANCE 2021; 52:1321-1342. [PMID: 34744319 PMCID: PMC8570533 DOI: 10.1007/s00723-021-01376-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 06/11/2021] [Accepted: 06/17/2021] [Indexed: 05/04/2023]
Abstract
OBJECTIVES (1) Summarize revisions made to the implantable resonator (IR) design and results of testing to characterize biocompatibility;(2) Demonstrate safety of implantation and feasibility of deep tissue oxygenation measurement using electron paramagnetic resonance (EPR) oximetry. STUDY DESIGN In vitro testing of the revised IR and in vivo implantation in rabbit brain and leg tissues. METHODS Revised IRs were fabricated with 1-4 OxyChips with a thin wire encapsulated with two biocompatible coatings. Biocompatibility and chemical characterization tests were performed. Rabbits were implanted with either an IR with 2 oxygen sensors or a biocompatible-control sample in both the brain and hind leg. The rabbits were implanted with IRs using a catheter-based, minimally invasive surgical procedure. EPR oximetry was performed for rabbits with IRs. Cohorts of rabbits were euthanized and tissues were obtained at 1 week, 3 months, and 9 months after implantation and examined for tissue reaction. RESULTS Biocompatibility and toxicity testing of the revised IRs demonstrated no abnormal reactions. EPR oximetry from brain and leg tissues were successfully executed. Blood work and histopathological evaluations showed no significant difference between the IR and control groups. CONCLUSIONS IRs were functional for up to 9 months after implantation and provided deep tissue oxygen measurements using EPR oximetry. Tissues surrounding the IRs showed no more tissue reaction than tissues surrounding the control samples. This pre-clinical study demonstrates that the IRs can be safely implanted in brain and leg tissues and that repeated, non-invasive, deep-tissue oxygen measurements can be obtained using in vivo EPR oximetry.
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Affiliation(s)
- Eunice Y. Chen
- Section of Otolaryngology, Department of Surgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States and Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Dan Tse
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| | - Huagang Hou
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| | - Wilson A. Schreiber
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| | - Philip E. Schaner
- Section of Radiation Oncology, Department of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States and Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Maciej M. Kmiec
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| | - Kendra A. Hebert
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| | - Periannan Kuppusamy
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| | - Harold M. Swartz
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
- Section of Radiation Oncology, Department of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States and Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Benjamin B. Williams
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
- Section of Radiation Oncology, Department of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States and Geisel School of Medicine at Dartmouth, Hanover, NH
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Electrospun nanofiber-based cancer sensors: A review. Int J Pharm 2020; 583:119364. [DOI: 10.1016/j.ijpharm.2020.119364] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 04/20/2020] [Accepted: 04/21/2020] [Indexed: 12/27/2022]
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Estimation of pO2 histogram from a composite EPR Spectrum of multiple random implants. Biomed Microdevices 2019; 22:3. [DOI: 10.1007/s10544-019-0451-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Biocompatibility of Oxygen-Sensing Paramagnetic Implants. Cell Biochem Biophys 2019; 77:197-202. [PMID: 31444784 DOI: 10.1007/s12013-019-00881-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 08/06/2019] [Indexed: 12/31/2022]
Abstract
Oxygen-sensing implants, composed of paramagnetic microcrystals embedded in a biocompatible polymer, are increasingly being used for electron paramagnetic resonance (EPR) oximetry in animal models and human subjects. The implants are stable and designed to stay in the tissues for indefinite periods. However, it is not known whether the crystals that may be exposed on the surface of the implants or leached out from the implants will induce cytotoxicity thereby compromising their biocompatibility over the long term. The goal of the current study was to evaluate the cytotoxicity of the implants and crystalline particulates under in vitro conditions. Apoptosis and cell viability studies were performed using L6, a rat muscle cell line and AsPC-1, a cancer cell line derived from human pancreatic adenocarcinoma. The results indicated that neither the intact implants nor their components elicit cytotoxicity, thus establishing their biocompatibility for use in human subjects.
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Implantable microchip containing oxygen-sensing paramagnetic crystals for long-term, repeated, and multisite in vivo oximetry. Biomed Microdevices 2019; 21:71. [PMID: 31286244 DOI: 10.1007/s10544-019-0421-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
EPR oximetry is established as a viable method for measuring the tissue oxygen level (partial pressure of oxygen, pO2) in animal models; however, it has not yet been established for measurements in humans. EPR oximetry requires an oxygen-sensing paramagnetic probe (molecular or particulate) to be placed at the site/organ of measurement, which may pose logistical and safety concerns, including invasiveness of the probe-placement procedure as well as lack of temporal stability and sensitivity for long-term (repeated) measurements, and possible toxicity in the short- and long-term. In the past, we have developed an implantable oxygen-sensing probe, called OxyChip, which we have successfully established for oximetry in pre-clinical animal models (Hou et al. Biomed. Microdevices 20, 29, 2018). Currently, OxyChip is being evaluated in a limited clinical trial in cancer patients. A major limitation of OxyChip is that it is a large (1.4 mm3) implant and hence not suitable for measuring oxygen heterogeneity that may be present in solid tumors, chronic wounds, etc. In this report, we describe the development of a substantially smaller version of OxyChip (0.07 mm3 or 70 cubic micron), called mChip, that can be placed in the tissue of interest using a 23G syringe-needle with minimal invasiveness. Using in vitro and in vivo models, we have shown that the microchip provides adequate EPR sensitivity, stability, and biocompatibility and thus enables robust, repeated, and simultaneous measurement from multiple implants providing mean and median pO2 values in the implanted region. The mChips will be particularly useful for those applications that require repeated measurements of mean/median pO2 in superficial tissues and malignancies.
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Sato-Akaba H, Tseytlin M. Development of an L-band rapid scan EPR digital console. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 304:42-52. [PMID: 31100585 PMCID: PMC7549020 DOI: 10.1016/j.jmr.2019.05.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 06/05/2023]
Abstract
The development of a digital console for in-vivo rapid scan electron paramagnetic resonance (RS-EPR) spectroscopy and imaging is described in detail. The console was build using field programmable gate array (FGPA) technology that permits real-time control of the resonator and scanning magnetic fields during the measurements. Automatic resonator tuning and matching are achieved by implementing a digital feedback control system and using voltage-tunable capacitors. A band-pass subsampling method is used to directly digitize EPR signals at the carrier frequencies of about 1.2 GHz. The magnetic field scan waveforms, excitation EPR frequency, and sampling clock are all internally synchronized. Full-cycle RS-EPR signals are accumulated in the FPGA in real time without any time gaps. The result is the elimination of the re-arm time, during which data are not acquired. The proposed design in this manuscript has a small footprint and is relatively low cost. The FPGA-based RS-EPR system was tested using standard LiNc-BuO and tempone-d16 samples. The RS-EPR linewidth of the LiNc-BuO sample was consistent with an independent pulsed EPR measurement.
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Affiliation(s)
- Hideo Sato-Akaba
- Department of Systems Innovation, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Mark Tseytlin
- Department of Biochemistry, School of Medicine, West Virginia University, Morgantown, WV, USA
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Oxygenic photosynthesis: EPR study of photosynthetic electron transport and oxygen-exchange, an overview. Cell Biochem Biophys 2018; 77:47-59. [PMID: 30460441 DOI: 10.1007/s12013-018-0861-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 11/01/2018] [Indexed: 12/28/2022]
Abstract
In this review, we consider the applications of electron paramagnetic resonance (EPR) methods to the study of the relationships between the electron transport and oxygen-exchange processes in photosynthetic systems of oxygenic type. One of the purposes of this article is to encourage scientists to use the advantageous EPR oximetry approaches to study oxygen-related electron transport processes in photosynthetic systems. The structural organization of the photosynthetic electron transfer chain and the EPR approaches to the measurements of molecular oxygen (O2) with O2-sensitive species (nitroxide spin labels and solid paramagnetic particles) are briefly reviewed. In solution, the collision of O2 with spin probes causes the broadening of their EPR spectra and the reduction of their spin-lattice relaxation times. Based on these effects, tools for measuring O2 concentration and O2 diffusion in biological systems have been developed. These methods, named "spin-label oximetry," include not only nitroxide spin labels, but also other stable-free radicals with narrow EPR lines, as well as particulate probes with EPR spectra sensitive to molecular oxygen (lithium phthalocyanine, coals, and India ink). Applications of EPR approaches for measuring O2 evolution and consumption are illustrated using examples of photosynthetic systems of oxygenic type, chloroplasts in situ (green leaves), and cyanobacteria.
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Kmiec MM, Hou H, Lakshmi Kuppusamy M, Drews TM, Prabhat AM, Petryakov SV, Demidenko E, Schaner PE, Buckey JC, Blank A, Kuppusamy P. Transcutaneous oxygen measurement in humans using a paramagnetic skin adhesive film. Magn Reson Med 2018; 81:781-794. [PMID: 30277275 DOI: 10.1002/mrm.27445] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 06/11/2018] [Accepted: 06/11/2018] [Indexed: 01/20/2023]
Abstract
PURPOSE Transcutaneous oxygen tension (TcpO2 ) provides information about blood perfusion in the tissue immediately below the skin. These data are valuable in assessing wound healing problems, diagnosing peripheral vascular/arterial insufficiency, and predicting disease progression or the response to therapy. Currently, TcpO2 is primarily measured using electrochemical skin sensors, which consume oxygen and are prone to calibration errors. The goal of the present study was to develop a reliable method for TcpO2 measurement in human subjects. METHODS We have developed a novel TcpO2 oximetry method based on electron paramagnetic resonance (EPR) principles with an oxygen-sensing skin adhesive film, named the superficial perfusion oxygen tension (SPOT) chip. The SPOT chip is a 3-mm diameter, 60-μm thick circular film composed of a stable paramagnetic oxygen sensor. The chip is covered with an oxygen-barrier material on one side and secured on the skin by a medical adhesive transfer tape to ensure that only the oxygen that diffuses through the skin surface is measured. The method quantifies TcpO2 through the linewidth of the EPR spectrum. RESULTS Repeated measurements using a cohort of 10 healthy human subjects showed that the TcpO2 measurements were robust, reliable, and reproducible. The TcpO2 values ranged from 7.8 ± 0.8 to 22.0 ± 1.0 mmHg in the volar forearm skin (N = 29) and 8.1 ± 0.3 to 23.4 ± 1.3 mmHg in the foot (N = 86). CONCLUSIONS The results demonstrated that the SPOT chip can measure TcpO2 reliably and repeatedly under ambient conditions. The SPOT chip method could potentially be used to monitor TcpO2 in the clinic.
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Affiliation(s)
- Maciej M Kmiec
- Department of Radiology, Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire
| | - Huagang Hou
- Department of Radiology, Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire
| | - M Lakshmi Kuppusamy
- Department of Radiology, Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire
| | - Thomas M Drews
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts
| | - Anjali M Prabhat
- Department of Radiology, Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire
| | - Sergey V Petryakov
- Department of Radiology, Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire
| | - Eugene Demidenko
- Department of Biomedical Data Sciences, Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire
| | - Philip E Schaner
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire
| | - Jay C Buckey
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire
| | - Aharon Blank
- Schulich Faculty of Chemistry Technion, Israel Institute of Technology, Haifa, Israel
| | - Periannan Kuppusamy
- Department of Radiology, Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire.,Department of Chemistry, University of Massachusetts, Amherst, Massachusetts
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13
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Khramtsov VV. In Vivo Molecular Electron Paramagnetic Resonance-Based Spectroscopy and Imaging of Tumor Microenvironment and Redox Using Functional Paramagnetic Probes. Antioxid Redox Signal 2018; 28:1365-1377. [PMID: 29132215 PMCID: PMC5910053 DOI: 10.1089/ars.2017.7329] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
SIGNIFICANCE A key role of the tumor microenvironment (TME) in cancer progression, treatment resistance, and as a target for therapeutic intervention is increasingly appreciated. Among important physiological components of the TME are tissue hypoxia, acidosis, high reducing capacity, elevated concentrations of intracellular glutathione (GSH), and interstitial inorganic phosphate (Pi). Noninvasive in vivo pO2, pH, GSH, Pi, and redox assessment provide unique insights into biological processes in the TME, and may serve as a tool for preclinical screening of anticancer drugs and optimizing TME-targeted therapeutic strategies. Recent Advances: A reasonable radiofrequency penetration depth in living tissues and progress in development of functional paramagnetic probes make low-field electron paramagnetic resonance (EPR)-based spectroscopy and imaging the most appropriate approaches for noninvasive assessment of the TME parameters. CRITICAL ISSUES Here we overview the current status of EPR approaches used in combination with functional paramagnetic probes that provide quantitative information on chemical TME and redox (pO2, pH, redox status, Pi, and GSH). In particular, an application of a recently developed dual-function pH and redox nitroxide probe and multifunctional trityl probe provides unsurpassed opportunity for in vivo concurrent measurements of several TME parameters in preclinical studies. The measurements of several parameters using a single probe allow for their correlation analyses independent of probe distribution and time of measurements. FUTURE DIRECTIONS The recent progress in clinical EPR instrumentation and development of biocompatible paramagnetic probes for in vivo multifunctional TME profiling eventually will make possible translation of these EPR techniques into clinical settings to improve prediction power of early diagnostics for the malignant transition and for future rational design of TME-targeted anticancer therapeutics. Antioxid. Redox Signal. 28, 1365-1377.
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Affiliation(s)
- Valery V Khramtsov
- 1 In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University , Morgantown, West Virginia.,2 Department of Biochemistry, West Virginia University School of Medicine , Morgantown, West Virginia
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14
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Enomoto A, Qian C, Devasahayam N, Kishimoto S, Oshima N, Blackman B, Swenson RE, Mitchell JB, Koretsky AP, Krishna MC. Wireless implantable coil with parametric amplification for in vivo electron paramagnetic resonance oximetric applications. Magn Reson Med 2018; 80:2288-2298. [PMID: 29603378 DOI: 10.1002/mrm.27185] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 02/23/2018] [Accepted: 02/28/2018] [Indexed: 11/06/2022]
Abstract
PURPOSE To develop an implantable wireless coil with parametric amplification capabilities for time-domain electron paramagnetic resonance (EPR) spectroscopy operating at 300 MHz. METHODS The wireless coil and lithium phthalocyanine (LiPc), a solid paramagnetic probe, were each embedded individually in a biocompatible polymer polydimethoxysiloxane (PDMS). EPR signals from the LiPc embedded in PDMS (LiPc/PDMS) were generated by a transmit-receive surface coil tuned to 300 MHz. Parametric amplification was configured with an external pumping coil tuned to 600 MHz and placed between the surface coil resonator and the wireless coil. RESULTS Phantom studies showed significant enhancement in signal to noise using the pumping coil. However, no influence of the pumping coil on the oxygen-dependent EPR spectral linewidth of LiPc/PDMS was observed, suggesting the validity of parametric amplification of EPR signals for oximetry by implantation of the encapsulated wireless coil and LiPc/PDMS in deep regions of live objects. In vivo studies demonstrate the feasibility of this approach to longitudinally monitor tissue pO2 in vivo and also monitor acute changes in response to pharmacologic challenges. The encapsulated wireless coil and LiPc/PDMS engendered no host immune response when implanted for ∼3 weeks and were found to be well tolerated. CONCLUSIONS This approach may find applications for monitoring tissue oxygenation to better understand the pathophysiology associated with wound healing, organ transplantation, and ischemic diseases.
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Affiliation(s)
- Ayano Enomoto
- Radiation Biology Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Chunqi Qian
- Laboratory of Functional and Molecular Imaging, NINDS, NIH, Bethesda, Maryland.,Department of Radiology, Michigan State University, East Lansing, Michigan
| | | | - Shun Kishimoto
- Radiation Biology Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Nobu Oshima
- Urologic Oncology Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | | | - Rolf E Swenson
- Image Probe Development Center, NHLBI, NIH, Bethesda, Maryland
| | - James B Mitchell
- Radiation Biology Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, NINDS, NIH, Bethesda, Maryland
| | - Murali C Krishna
- Radiation Biology Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
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15
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16
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Hou H, Khan N, Kuppusamy P. Measurement of pO2 in a Pre-clinical Model of Rabbit Tumor Using OxyChip, a Paramagnetic Oxygen Sensor. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 977:313-318. [DOI: 10.1007/978-3-319-55231-6_41] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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17
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Abstract
EPR (electron paramagnetic resonance) based biological oximetry is a powerful tool that accurately and repeatedly measures tissue oxygen levels. In vivo determination of oxygen in tissues is crucial for the diagnosis and treatment of a number of diseases. Here, we report the first successful fabrication and remarkable properties of nanofiber sensors for EPR-oximetry applications. Lithium octa-n-butoxynaphthalocyanine (LiNc- BuO), an excellent paramagnetic oxygen sensor, was successfully encapsulated in 300-500 nm diameter fibers consisting of a core of polydimethylsiloxane (PDMS) and a shell of polycaprolactone (PCL) by electrospinning. This core-shell nanosensor (LiNc-BuO-PDMS-PCL) shows a linear dependence of linewidth versus oxygen partial pressure (pO2). The nanofiber sensors have response and recovery times of 0.35 s and 0.55 s, respectively, these response and recovery times are ~12 times and ~218 times faster than those previously reported for PDMS-LiNc-BuO chip sensors. This greater responsiveness is likely due to the high porosity and excellent oxygen permeability of the nanofibers. Electrospinning of the structurally flexible PDMS enabled the fabrication of fibers having tailored spin densities. Core-shell encapsulation ensures the non-exposure of embedded LiNc-BuO and mitigates potential biocompatibility concerns. In vitro evaluation of the fiber performed under exposure to cultured cells showed that it is both stable and biocompatible. The unique combination of biocompatibility due to the PCL 'shell,' the excellent oxygen transparency of the PDMS core, and the excellent oxygen-sensing properties of LiNc-BuO makes LiNc-BuO-PDMS-PCL platform promising for long-term oximetry and repetitive oxygen measurements in both biological systems and clinical applications.
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18
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Hou H, Khan N, Nagane M, Gohain S, Chen EY, Jarvis LA, Schaner PE, Williams BB, Flood AB, Swartz HM, Kuppusamy P. Skeletal Muscle Oxygenation Measured by EPR Oximetry Using a Highly Sensitive Polymer-Encapsulated Paramagnetic Sensor. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 923:351-357. [PMID: 27526163 DOI: 10.1007/978-3-319-38810-6_46] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We have incorporated LiNc-BuO, an oxygen-sensing paramagnetic material, in polydimethylsiloxane (PDMS), which is an oxygen-permeable, biocompatible, and stable polymer. We fabricated implantable and retrievable oxygen-sensing chips (40 % LiNc-BuO in PDMS) using a 20-G Teflon tubing to mold the chips into variable shapes and sizes for in vivo studies in rats. In vitro EPR measurements were used to test the chip's oxygen response. Oxygen induced linear and reproducible line broadening with increasing partial pressure (pO2). The oxygen response was similar to that of bare (unencapsulated) crystals and did not change significantly on sterilization by autoclaving. The chips were implanted in rat femoris muscle and EPR oximetry was performed repeatedly (weekly) for 12 weeks post-implantation. The measurements showed good reliability and reproducibility over the period of testing. These results demonstrated that the new formulation of OxyChip with 40 % LiNc-BuO will enable the applicability of EPR oximetry for long-term measurement of oxygen concentration in tissues and has the potential for clinical applications.
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Affiliation(s)
- H Hou
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA.
| | - N Khan
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - M Nagane
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - S Gohain
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - E Y Chen
- Department of Surgery, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - L A Jarvis
- Department of Medicine, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - P E Schaner
- Department of Medicine, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - B B Williams
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA.,Department of Medicine, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - A B Flood
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - H M Swartz
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA.,Department of Medicine, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - P Kuppusamy
- Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA. .,Department of Medicine, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA. .,Department of Radiology, EPR Center for the Study of Viable Systems, Geisel School of Medicine at Dartmouth, One Medical Center Drive, Lebanon, NH, 03766, USA.
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19
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Frank J, Gündel D, Drescher S, Thews O, Mäder K. Injectable LiNc-BuO loaded microspheres as in vivo EPR oxygen sensors after co-implantation with tumor cells. Free Radic Biol Med 2015; 89:741-9. [PMID: 26459034 DOI: 10.1016/j.freeradbiomed.2015.10.401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 10/03/2015] [Accepted: 10/08/2015] [Indexed: 10/22/2022]
Abstract
Electron paramagnetic resonance (EPR) oximetry is a technique which allows accurate and repeatable oxygen measurements. We encapsulated a highly oxygen sensitive particulate EPR spin probe into microparticles to improve its dispersibility and, hence, facilitate the administration. These biocompatible, non-toxic microspheres contained 5-10 % (w/w) spin probe and had an oxygen sensitivity of 0.60 ± 0.01 µT/mmHg. To evaluate the performance of the microparticles as oxygen sensors, they were co-implanted with syngeneic tumor cells in 2 different rat strains. Thus, tissue injury was avoided and the microparticles were distributed all over the tumor tissue. Dynamic changes of the intratumoral oxygen partial pressure during inhalation of 8 %, 21 %, or 100 % oxygen were monitored in vivo by EPR spectroscopy and quantified. Values were verified in vivo by invasive fluorometric measurements using Oxylite probes and ex vivo by pimonidazole adduct accumulation. There were no hints that the tumor physiology or tissue oxygenation had been altered by the microparticles. Hence, these microprobes offer great potential as oxygen sensors in preclinical research, not only for EPR spectroscopy but also for EPR imaging. For instance, the assessment of tissue oxygenation during therapeutic interventions might help understanding pathophysiological processes and lead to an individualized treatment planning or the use of formulations with hypoxia triggered release of active agents.
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Affiliation(s)
- Juliane Frank
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany
| | - Daniel Gündel
- Julius-Bernstein-Institute of Physiology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 6, 06112 Halle (Saale), Germany
| | - Simon Drescher
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany
| | - Oliver Thews
- Julius-Bernstein-Institute of Physiology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 6, 06112 Halle (Saale), Germany.
| | - Karsten Mäder
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany.
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20
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Khan N, Hou H, Swartz HM, Kuppusamy P. Direct and Repeated Measurement of Heart and Brain Oxygenation Using In Vivo EPR Oximetry. Methods Enzymol 2015; 564:529-52. [PMID: 26477264 DOI: 10.1016/bs.mie.2015.06.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Low level of oxygen (hypoxia) is a critical factor that defines the pathological consequence of several pathophysiologies, particularly ischemia, that usually occur following the blockage of a blood vessel in vital organs, such as brain and heart, or abnormalities in the microvasculature, such as peripheral vascular disease. Therefore, methods that can directly and repeatedly quantify oxygen levels in the brain and heart will significantly improve our understanding of ischemic pathologies. Importantly, such oximetry capability will facilitate the development of strategies to counteract low levels of oxygen and thereby improve outcome following stroke or myocardial infarction. In vivo electron paramagnetic resonance (EPR) oximetry has the capability to monitor tissue oxygen levels in real time. The method has largely been tested and used in experimental animals, although some clinical measurements have been performed. In this chapter, a brief overview of the methodology to repeatedly quantify oxygen levels in the brain and heart of experimental animal models, ranging from mice to swine, is presented. EPR oximetry requires a one-time placement of an oxygen-sensitive probe in the tissue of interest, while the rest of the procedure for reliable, accurate, and repeated measurements of pO2 (partial pressure of oxygen) is noninvasive and can be repeated as often as desired. A multisite oximetry approach can be used to monitor pO2 at many sites simultaneously. Building on significant advances in the application of EPR oximetry in experimental animal models, spectrometers have been developed for use in human subjects. Initial feasibility of pO2 measurement in solid tumors of patients has been successfully demonstrated.
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Affiliation(s)
- Nadeem Khan
- Department of Radiology, EPR Center for the Study of Viable Systems, Geisel School of Medicine at Dartmouth, Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Huagang Hou
- Department of Radiology, EPR Center for the Study of Viable Systems, Geisel School of Medicine at Dartmouth, Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Harold M Swartz
- Department of Radiology, EPR Center for the Study of Viable Systems, Geisel School of Medicine at Dartmouth, Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Periannan Kuppusamy
- Department of Radiology, EPR Center for the Study of Viable Systems, Geisel School of Medicine at Dartmouth, Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA.
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21
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Noninvasive monitoring of small intestinal oxygen in a rat model of chronic mesenteric ischemia. Cell Biochem Biophys 2014; 67:451-9. [PMID: 23636684 DOI: 10.1007/s12013-013-9611-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We noninvasively monitored the partial pressure of oxygen (pO2) in rat's small intestine using a model of chronic mesenteric ischemia by electron paramagnetic resonance oximetry over a 7-day period. The particulate probe lithium octa-n-butoxynaphthalocyanine (LiNc-BuO) was embedded into the oxygen permeable material polydimethyl siloxane by cast-molding and polymerization (Oxy-Chip). A one-time surgical procedure was performed to place the Oxy-Chip on the outer wall of the small intestine (SI). The superior mesenteric artery (SMA) was banded to ~30% of blood flow for experimental rats. Noninvasive measurement of pO2 was performed at the baseline for control rats or immediate post-banding and on days 1, 3, and 7. The SI pO2 for control rats remained stable over the 7-day period. The pO2 on day-7 was 54.5 ± 0.9 mmHg (mean ± SE). SMA-banded rats were significantly different from controls with a noted reduction in pO2 post banding with a progressive decline to a final pO2 of 20.9 ± 4.5 mmHg (mean ± SE; p = 0.02). All SMA-banded rats developed adhesions around the Oxy-Chip, yet remained asymptomatic. The hypoxia marker Hypoxyprobe™ was used to validate the low tissue pO2. Brown cytoplasmic staining was consistent with hypoxia. Mild brown staining was noted predominantly on the villus tips in control animals. SMA-banded rats had an extended region of hypoxic involvement in the villus with a higher intensity of cytoplasmic staining. Deep brown stainings of the enteric nervous system neurons and connective tissue both within layers and in the mesentery were noted. SMA-banded rats with lower pO2 values had a higher intensity of staining. Thus, monitoring SI pO2 using the probe Oxy-Chip provides a valid measure of tissue oxygenation. Tracking pO2 in conditions that produce chronic mesenteric ischemia will contribute to our understanding of intestinal tissue oxygenation and how changes impact symptom evolution and the trajectory of chronic disease.
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22
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Swartz HM, Williams BB, Zaki BI, Hartford AC, Jarvis LA, Chen EY, Comi RJ, Ernstoff MS, Hou H, Khan N, Swarts SG, Flood AB, Kuppusamy P. Clinical EPR: unique opportunities and some challenges. Acad Radiol 2014; 21:197-206. [PMID: 24439333 DOI: 10.1016/j.acra.2013.10.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 10/03/2013] [Accepted: 10/14/2013] [Indexed: 11/29/2022]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy has been well established as a viable technique for measurement of free radicals and oxygen in biological systems, from in vitro cellular systems to in vivo small animal models of disease. However, the use of EPR in human subjects in the clinical setting, although attractive for a variety of important applications such as oxygen measurement, is challenged with several factors including the need for instrumentation customized for human subjects, probe, and regulatory constraints. This article describes the rationale and development of the first clinical EPR systems for two important clinical applications, namely, measurement of tissue oxygen (oximetry) and radiation dose (dosimetry) in humans. The clinical spectrometers operate at 1.2 GHz frequency and use surface-loop resonators capable of providing topical measurements up to 1 cm depth in tissues. Tissue pO2 measurements can be carried out noninvasively and repeatedly after placement of an oxygen-sensitive paramagnetic material (currently India ink) at the site of interest. Our EPR dosimetry system is capable of measuring radiation-induced free radicals in the tooth of irradiated human subjects to determine the exposure dose. These developments offer potential opportunities for clinical dosimetry and oximetry, which include guiding therapy for individual patients with tumors or vascular disease by monitoring of tissue oxygenation. Further work is in progress to translate this unique technology to routine clinical practice.
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Affiliation(s)
- Harold M Swartz
- Department of Radiology, Geisel School of Medicine at Dartmouth, Dartmouth College, 48 Lafayette Street, Lebanon, NH 03766.
| | - Benjamin B Williams
- Department of Radiology, Geisel School of Medicine at Dartmouth, Dartmouth College, 48 Lafayette Street, Lebanon, NH 03766
| | - Bassem I Zaki
- Department of Medicine, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH
| | - Alan C Hartford
- Department of Medicine, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH
| | - Lesley A Jarvis
- Department of Medicine, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH
| | - Eunice Y Chen
- Department of Surgery, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH
| | - Richard J Comi
- Department of Medicine, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH
| | - Marc S Ernstoff
- Department of Medicine, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH
| | - Huagang Hou
- Department of Radiology, Geisel School of Medicine at Dartmouth, Dartmouth College, 48 Lafayette Street, Lebanon, NH 03766
| | - Nadeem Khan
- Department of Radiology, Geisel School of Medicine at Dartmouth, Dartmouth College, 48 Lafayette Street, Lebanon, NH 03766
| | - Steven G Swarts
- Dept. of Radiation Oncology, University of Florida, Gainesville, FL
| | - Ann B Flood
- Department of Radiology, Geisel School of Medicine at Dartmouth, Dartmouth College, 48 Lafayette Street, Lebanon, NH 03766
| | - Periannan Kuppusamy
- Department of Radiology, Geisel School of Medicine at Dartmouth, Dartmouth College, 48 Lafayette Street, Lebanon, NH 03766
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23
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Swartz HM, Hou H, Khan N, Jarvis LA, Chen EY, Williams BB, Kuppusamy P. Advances in probes and methods for clinical EPR oximetry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 812:73-79. [PMID: 24729217 DOI: 10.1007/978-1-4939-0620-8_10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
EPR oximetry, which enables reliable, accurate, and repeated measurements of the partial pressure of oxygen in tissues, provides a unique opportunity to investigate the role of oxygen in the pathogenesis and treatment of several diseases including cancer, stroke, and heart failure. Building on significant advances in the in vivo application of EPR oximetry for small animal models of disease, we are developing suitable probes and instrumentation required for use in human subjects. Our laboratory has established the feasibility of clinical EPR oximetry in cancer patients using India ink, the only material presently approved for clinical use. We now are developing the next generation of probes, which are both superior in terms of oxygen sensitivity and biocompatibility including an excellent safety profile for use in humans. Further advances include the development of implantable oxygen sensors linked to an external coupling loop for measurements of deep-tissue oxygenations at any depth, overcoming the current limitation of 10 mm. This paper presents an overview of recent developments in our ability to make meaningful measurements of oxygen partial pressures in human subjects under clinical settings.
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Affiliation(s)
- Harold M Swartz
- EPR Center for the Study of Viable Systems, The Geisel School of Medicine at Dartmouth, Lebanon, NH, 03766, USA.
| | - Huagang Hou
- EPR Center for the Study of Viable Systems, Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, 48 Lafayette Street, HB 7785, Lebanon, NH, 03766, USA
| | - Nadeem Khan
- EPR Center for the Study of Viable Systems, Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, 48 Lafayette Street, HB 7785, Lebanon, NH, 03766, USA
| | - Lesley A Jarvis
- Department of Medicine, Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA
| | - Eunice Y Chen
- Department of Surgery, Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA
| | - Benjamin B Williams
- EPR Center for the Study of Viable Systems, Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, 48 Lafayette Street, HB 7785, Lebanon, NH, 03766, USA
| | - Periannan Kuppusamy
- EPR Center for the Study of Viable Systems, Department of Radiology, Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, 48 Lafayette Street, HB 7785, Lebanon, NH, 03766, USA
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Repeated assessment of orthotopic glioma pO(2) by multi-site EPR oximetry: a technique with the potential to guide therapeutic optimization by repeated measurements of oxygen. J Neurosci Methods 2011; 204:111-117. [PMID: 22079559 DOI: 10.1016/j.jneumeth.2011.10.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/29/2011] [Accepted: 10/27/2011] [Indexed: 01/27/2023]
Abstract
Tumor hypoxia plays a vital role in therapeutic resistance. Consequently, measurements of tumor pO(2) could be used to optimize the outcome of oxygen-dependent therapies, such as, chemoradiation. However, the potential optimizations are restricted by the lack of methods to repeatedly and quantitatively assess tumor pO(2) during therapies, particularly in gliomas. We describe the procedures for repeated measurements of orthotopic glioma pO(2) by multi-site electron paramagnetic resonance (EPR) oximetry. This oximetry approach provides simultaneous measurements of pO(2) at more than one site in the glioma and contralateral cerebral tissue. The pO(2) of intracerebral 9L, C6, F98 and U251 tumors, as well as contralateral brain, were measured repeatedly for five consecutive days. The 9L glioma was well oxygenated with pO(2) of 27-36 mm Hg, while C6, F98 and U251 glioma were hypoxic with pO(2) of 7-12mm Hg. The potential of multi-site EPR oximetry to assess temporal changes in tissue pO(2) was investigated in rats breathing 100% O(2). A significant increase in F98 tumor and contralateral brain pO(2) was observed on day 1 and day 2, however, glioma oxygenation declined on subsequent days. In conclusion, EPR oximetry provides the capability to repeatedly assess temporal changes in orthotopic glioma pO(2). This information could be used to test and optimize the methods being developed to modulate tumor hypoxia. Furthermore, EPR oximetry could be potentially used to enhance the outcome of chemoradiation by scheduling treatments at times of increase in glioma pO(2).
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25
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Challenges to intestinal pO₂ measurement using EPR. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 701:37-44. [PMID: 21445767 DOI: 10.1007/978-1-4419-7756-4_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Acute and chronic intestinal ischemia has been linked to the development of gastrointestinal symptoms such as abdominal pain, nausea and vomiting, bowel dysfunction and more seriously, the complications of sepsis, shock and death. Advances in electron paramagnetic resonance (EPR) oximetry have resulted in accurate and reliable in vivo measurement of the partial pressure of oxygen (pO(2)) in solid organs (e.g., muscle, heart) [1], but has yet to be tested in thin walled organs such as intestine. Our ultimate goal is to noninvasively monitor intestinal pO(2) during acute and chronic intestinal ischemia in a rat model. A series of experiments to deliver oxygen-sensitive indicator probes to the small/large intestine by intravenous, luminal and wall injection, as well as direct placement of a solid probe against the outer intestinal wall were attempted. Only the LiNc:BuO:PDMS chip sutured to the peritoneal wall and in direct contact with the intestine allowed for noninvasive pO(2) measurement by EPR. However, the validity of site-specific intestinal pO(2) measurement could not be confirmed and the obtained pO(2) value likely reflected peritoneal cavity oxygenation. Developing methods for probe placement on or inside the intestinal wall are needed for noninvasive, site-specific intestinal pO(2) measurement by EPR to track changes during acute and chronic intestinal ischemia.
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26
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Meenakshisundaram G, Eteshola E, Blank A, Lee SC, Kuppusamy P. A molecular paramagnetic spin-doped biopolymeric oxygen sensor. Biosens Bioelectron 2010; 25:2283-9. [PMID: 20371170 PMCID: PMC2866758 DOI: 10.1016/j.bios.2010.03.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 03/01/2010] [Accepted: 03/08/2010] [Indexed: 11/15/2022]
Abstract
Electron paramagnetic resonance (EPR) oximetry is a powerful technique capable of providing accurate, reliable, and repeated measurements of tissue oxygenation, which is crucial to the diagnosis and treatment of several pathophysiological conditions. Measurement of tissue pO(2) by EPR involves the use of paramagnetic, oxygen-sensitive probes, which can be either soluble (molecular) in nature or insoluble paramagnetic materials. Development of innovative strategies to enhance the biocompatibility and in vivo application of these oxygen-sensing probes is crucial to the growth and clinical applicability of EPR oximetry. Recent research efforts have aimed at encapsulating particulate probes in bioinert polymers for the development of biocompatible EPR probes. In this study, we have developed novel EPR oximetry probes, called perchlorotriphenylmethyl triester (PTM-TE):polydimethyl siloxane (PDMS) chips, by dissolving and incorporating the soluble (molecular) EPR probe, PTM-TE, in an oxygen-permeable polymer matrix, PDMS. We demonstrate that such incorporation (doping) of PTM-TE in PDMS enhanced its oxygen sensitivity several fold. The cast-molding method of fabricating chips enabled them to be made with increasing amounts of PTM-TE (spin density). Characterization of the spin distribution within the PDMS matrix, using EPR micro-imaging, revealed potential inhomogeneties, albeit with no adverse effect on the oxygen-sensing characteristics of PTM-TE:PDMS. The chips were resistant to autoclaving or in vitro oxidoreductant treatment, thus exhibiting excellent in vitro biostability. Our results establish PTM-TE:PDMS as a viable probe for biological oxygen-sensing, and also validate the incorporation of soluble probes in polymer matrices as an innovative approach to the development of novel probes for EPR oximetry.
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Affiliation(s)
- Guruguhan Meenakshisundaram
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Edward Eteshola
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - Aharon Blank
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 32000, Israel
| | - Stephen C. Lee
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - Periannan Kuppusamy
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
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Pandian RP, Meenakshisundaram G, Bratasz A, Eteshola E, Lee SC, Kuppusamy P. An implantable Teflon chip holding lithium naphthalocyanine microcrystals for secure, safe, and repeated measurements of pO2 in tissues. Biomed Microdevices 2010; 12:381-7. [PMID: 20058084 PMCID: PMC2860037 DOI: 10.1007/s10544-009-9394-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Lithium naphthalocyanine (LiNc) is a crystalline material that has significant potential as a probe for EPR (electron paramagnetic resonance)-based biological oximetry (Pandian et al. J. Mater. Chem. 19:4138-4147, 2009a). However, implantation of LiNc crystals in tissues in raw or neat form is undesirable since dispersion of crystals in tissue may lead to loss of EPR signal, while also exacerbating biocompatibility concerns due to tissue exposure. To overcome these concerns, we have encapsulated LiNc crystals in an oxygen-permeable polymer, Teflon AF 2400 (TAF). Fabrication of TAF films incorporating LiNc particles (denoted as LiNc:TAF chip) was carried out using solvent-evaporation techniques. The EPR linewidth of LiNc:TAF chip was linearly dependent on oxygen-partial pressure (pO(2)) and did not change significantly relative to neat LiNc crystals. LiNc:TAF chip responded to changes in pO(2) reproducibly, enabling dynamic measurements of oxygenation in real time. The LiNc:TAF chips were stable in tissues for more than 2 months and were capable of providing repeated measurements of tissue oxygenation for extended periods of time. The results demonstrated that the newly fabricated, highly oxygen-sensitive LiNc:TAF chip will enhance the applicability of EPR oximetry for long-term and clinical applications.
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Affiliation(s)
- Ramasamy P. Pandian
- Center for Biomedical and EPR Spectroscopy Imaging, Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University, 420 West 12th Avenue, Room 114, Columbus, OH 43210, USA
| | - Guruguhan Meenakshisundaram
- Center for Biomedical and EPR Spectroscopy Imaging, Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University, 420 West 12th Avenue, Room 114, Columbus, OH 43210, USA
| | - Anna Bratasz
- Center for Biomedical and EPR Spectroscopy Imaging, Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University, 420 West 12th Avenue, Room 114, Columbus, OH 43210, USA
| | - Edward Eteshola
- Department of Biomedical Engineering, Davis Heart and Lung Research Institute, The Ohio State University, 420 West 12th Avenue, Room 114, Columbus, OH 43210, USA
| | - Stephen C. Lee
- Department of Biomedical Engineering, Davis Heart and Lung Research Institute, The Ohio State University, 420 West 12th Avenue, Room 114, Columbus, OH 43210, USA
| | - Periannan Kuppusamy
- Center for Biomedical and EPR Spectroscopy Imaging, Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University, 420 West 12th Avenue, Room 114, Columbus, OH 43210, USA,
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28
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Ahmad R, Kuppusamy P. Theory, instrumentation, and applications of electron paramagnetic resonance oximetry. Chem Rev 2010; 110:3212-36. [PMID: 20218670 PMCID: PMC2868962 DOI: 10.1021/cr900396q] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Rizwan Ahmad
- Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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29
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Blank A, Halevy R, Shklyar M, Shtirberg L, Kuppusamy P. ESR micro-imaging of LiNc-BuO crystals in PDMS: spatial and spectral grain distribution. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 203:150-155. [PMID: 20045659 DOI: 10.1016/j.jmr.2009.12.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 12/13/2009] [Accepted: 12/14/2009] [Indexed: 05/28/2023]
Abstract
Microcrystals of lithium octa-n-butoxynaphthalocyanine (LiNc-BuO) in a bio-compatible and oxygen-permeable polymer matrix of poly-dimethyl-siloxane (PDMS) can be used for repetitive non-invasive imaging of oxygen in live specimens by means of mm-scale electron spin resonance (ESR) imaging. This probe denoted as "oxychip" was characterized by high-resolution mum-scale ESR microcopy to reveal the fine details of its spatial and spectral properties. The ESR micro-images of a typical oxychip device showed that while the spatial distribution of the microcrystals in the polymer is fairly homogenous (as revealed by optical microscopy), the ESR signal originates only from a very few dominant crystals. Furthermore, spectral-spatial analysis in a microcrystal and a sub-microcrystal spatial resolution reveals that each crystal has a slightly different g-factor and also exhibits variations in linewidth, possibly due to the slightly different individual crystallization process.
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Affiliation(s)
- Aharon Blank
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 32000, Israel.
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30
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Meenakshisundaram G, Pandian RP, Eteshola E, Lee SC, Kuppusamy P. A paramagnetic implant containing lithium naphthalocyanine microcrystals for high-resolution biological oximetry. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 203:185-9. [PMID: 20006529 PMCID: PMC2822061 DOI: 10.1016/j.jmr.2009.11.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 10/02/2009] [Accepted: 11/20/2009] [Indexed: 05/21/2023]
Abstract
Lithium naphthalocyanine (LiNc) is a microcrystalline EPR oximetry probe with high sensitivity to oxygen [R.P. Pandian, M. Dolgos, C. Marginean, P.M. Woodward, P.C. Hammel, P.T. Manoharan, P. Kuppusamy, Molecular packing and magnetic properties of lithium naphthalocyanine crystal: hollow channels enabling permeability and paramagnetic sensitivity to molecular oxygen J. Mater. Chem. 19 (2009) 4138-4147]. However, direct implantation of the crystals in the tissue for in vivo oxygen measurements may be hindered by concerns associated with their direct contact with the tissue/cells and loss of EPR signal due to particle migration in the tissue. In order to address these concerns, we have developed encapsulations (chips) of LiNc microcrystals in polydimethyl siloxane (PDMS), an oxygen-permeable, bioinert polymer. Oximetry evaluation of the fabricated chips revealed that the oxygen sensitivity of the crystals was unaffected by encapsulation in PDMS. Chips were stable against sterilization procedures or treatment with common biological oxidoreductants. In vivo oxygen measurements established the ability of the chips to provide reliable and repeated measurements of tissue oxygenation. This study establishes PDMS-encapsulated LiNc as a potential probe for long-term and repeated measurements of tissue oxygenation.
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Affiliation(s)
- Guruguhan Meenakshisundaram
- Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210
| | - Ramasamy P. Pandian
- Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210
| | - Edward Eteshola
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210
| | - Stephen C. Lee
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210
| | - Periannan Kuppusamy
- Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210
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