Noninvasive in Vivo Monitoring of Drug Release and Polymer Erosion from Biodegradable Polymers by EPR Spectroscopy and NMR Imaging

Mäder, Karsten; Bačić, Goran; Domb, Abraham J.; Elmalak, Omar; Langer, Robert; Swartz, Harold M.

doi:10.1021/js9505105

Cited by 90 publications

(49 citation statements)

References 20 publications

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“…Aliphatic and aromatic homo -and copolymers were irradiated at 2.5 Mrad dose and the change in properties was monitored before and after irradiation. Properties such as molecular weight, melting temperature, and heat of fusion remained the same, and 1 HNMRand FTIR spectra of the polymer were also similar before and after irradiation [34,89] . Using the same concept, these studies were extended for saturated and unsaturated polyanhydrides [90] .…”

Section: Mechanical Polyanhydrides Show Poor Mechanical Properties mentioning

confidence: 69%

Polyanhydrides

Domb¹,

Jain²,

Kumar³

2011

Handbook of Biodegradable Polymers

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Section: Mechanical Polyanhydrides Show Poor Mechanical Properties mentioning

confidence: 69%

Polyanhydrides

Domb¹,

Jain²,

Kumar³

2011

Handbook of Biodegradable Polymers

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“…in which the paramagnetic species are located. [130][131][132][133] The key technical advances that were necessary to develop in vivo applications of EPR were: (1) instrumental development of spectrometers operating at low frequency (typically between 200 MHz and 1.5 GHz) suitable for use with animals; (2) development of detectors suitable for in vivo studies; (3) identification and development of paramagnetic compounds with properties suited for particular application (especially for the measurement of pO 2 ); and (4) improved methods for data acquisition and analysis.…”

Section: Short Relaxation Timesmentioning

confidence: 99%

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

2004

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This review paper attempts to provide an overview of the principles and techniques that are often termed electron paramagnetic resonance (EPR) oximetry. The paper discusses the potential of such methods and illustrates they have been successfully applied to measure oxygen tension, an essential parameter of the tumor microenvironment. To help the reader understand the motivation for carrying out these measurements, the importance of tumor hypoxia is first discussed: the basic issues of why a tumor is hypoxic, why these hypoxic microenvironments promote processes driving malignant progression and why hypoxia dramatically influences the response of tumors to cytotoxic treatments will be explained. The different methods that have been used to estimate the oxygenation in tumors will be reviewed. To introduce the basics of EPR oximetry, the specificity of in vivo EPR will be discussed by comparing this technique with NMR and MRI. The different types of paramagnetic oxygen sensors will be presented, as well as the methods for recording the information (EPR spectroscopy, EPR imaging, dynamic nuclear polarization). Several applications of EPR for characterizing tumor oxygenation will be illustrated, with a special emphasis on pharmacological interventions that modulate the tumor microenvironment. Finally, the challenges for transposing the method into the clinic will also be discussed.

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“…whether the implant is degrading uniformly or from the edges), and the pH within the implant. 34,107,108 Similarly the monitoring of the polymerization process in bone cement formation could be followed to provide direct information on the status of this complex therapeutic intervention. 109 It is likely that in vivo EPR could be of great practical use for both the development of implanted therapeutic systems and for monitoring the status of implants in individual patients.…”

Section: Characterization Of Drug Delivery Systemsmentioning

confidence: 99%

Clinical applications of EPR: overview and perspectives

et al. 2004

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The development and use of in vivo techniques for strictly experimental applications in animals has been very successful, and these results now have made possible some very attractive potential clinical applications. The area with the most obvious immediate, effective and widespread clinical use is oximetry, where EPR almost uniquely can make repeated and accurate measurements of pO 2 in tissues. Such measurements can provide clinicians with information that can impact directly on diagnosis and therapy, especially for oncology, peripheral vascular disease and wound healing. The other area of immediate and timely importance is the unique ability of in vivo EPR to measure clinically significant exposures to ionizing radiation 'after-the-fact', such as may occur due to accidents, terrorism or nuclear war. There are a number of other capabilities of in vivo EPR that also potentially could become extensively used in human subjects. In pharmacology the unique capabilities of in vivo EPR to detect and characterize free radicals could be applied to measure free radical intermediates from drugs and oxidative process. A closely related area of potential widespread applications is the use of EPR to measure nitric oxide. These often unique capabilities, combined with the sensitivity of EPR spectra to the immediate environment (e.g. pH, molecular motion, charge) have already resulted in some very productive applications in animals and these are likely to expand substantially in the near future. They should provide a continually developing base for extending clinical uses of in vivo EPR. The challenges for achieving full implementation include adapting the spectrometer for safe and comfortable measurements in human subjects, achieving sufficient sensitivity for measurements at the sites of the pathophysiological processes that are being measured, and establishing a consensus on the clinical value of the measurements.

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Noninvasive in Vivo Monitoring of Drug Release and Polymer Erosion from Biodegradable Polymers by EPR Spectroscopy and NMR Imaging

Cited by 90 publications

References 20 publications

Polyanhydrides

Polyanhydrides

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

Clinical applications of EPR: overview and perspectives

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