"Space—the final frontier." This preamble to a well-known television series captures the challenge encountered not only in space travel adventures, but also in the field of porous materials, which aims to control the size, shape and uniformity of the porous space and the atoms and molecules that define it. The past decade has seen significant advances in the ability to fabricate new porous solids with ordered structures from a wide range of different materials. This has resulted in materials with unusual properties and broadened their application range beyond the traditional use as catalysts and adsorbents. In fact, porous materials now seem set to contribute to developments in areas ranging from microelectronics to medical diagnosis.

Ordered porous materials for emerging applications

Photodynamic therapy involves administration of a tumor-localizing photosensitizing agent, which may require metabolic synthesis (i.e., a prodrug), followed by activation of the agent by light of a specific wavelength. This therapy results in a sequence of photochemical and photobiologic processes that cause irreversible photodamage to tumor tissues. Results from preclinical and clinical studies conducted worldwide over a 25-year period have established photodynamic therapy as a useful treatment approach for some cancers. Since 1993, regulatory approval for photodynamic therapy involving use of a partially purified, commercially available hematoporphyrin derivative compound (Photofrin) in patients with early and advanced stage cancer of the lung, digestive tract, and genitourinary tract has been obtained in Canada, The Netherlands, France, Germany, Japan, and the United States. We have attempted to conduct and present a comprehensive review of this rapidly expanding field. Mechanisms of subcellular and tumor localization of photosensitizing agents, as well as of molecular, cellular, and tumor responses associated with photodynamic therapy, are discussed. Technical issues regarding light dosimetry are also considered.

Photodynamic Therapy

Metal–organic frameworks (MOFs) display a wide range of luminescent behaviors resulting from the multifaceted nature of their structure. In this critical review we discuss the origins of MOF luminosity, which include the linker, the coordinated metal ions, antenna effects, excimer and exciplex formation, and guest molecules. The literature describing these effects is comprehensively surveyed, including a categorization of each report according to the type of luminescence observed. Finally, we discuss potential applications of luminescent MOFs. This review will be of interest to researchers and synthetic chemists attempting to design luminescent MOFs, and those engaged in the extension of MOFs to applications such as chemical, biological, and radiation detection, medical imaging, and electro-optical devices (141 references).

Luminescent Metal–Organic Frameworks

A. Water Exchange 2326 B. Proton Exchange 2327 C. Electronic Relaxation 2327 D. Relaxivity 2331 E. Outerand Second-Sphere Relaxivity 2334 F. Methods of Improving Relaxivity 2336 V. Macromolecular Conjugates 2336 A. Introduction 2336 B. General Conjugation Methods 2336 C. Synthetic Linear Polymers 2336 D. Synthetic Dendrimer-Based Agents 2338 E. Naturally Occurring Polymers (Proteins, Polysaccharides, and Nucleic Acids) 2339

https://mriquestions.com/uploads/3/4/5/7/34572113/lauffer_1999_review.pdf

Gadolinium(III) Chelates as MRI Contrast Agents: Structure, Dynamics, and Applications

Metal Organic Frameworks in Biomedicine Patricia Horcajada,* Ruxandra Gref, Tarek Baati, Phoebe K. Allan, Guillaume Maurin, Patrick Couvreur, G erard F erey, Russell E. Morris, and Christian Serre* Institut Lavoisier, UMR CNRS 8180, Universit e de Versailles St-Quentin en Yvelines, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France Facult e de Pharmacie, UMR CNRS 8612, Universit e Paris-Sud, 92296 Châtenay-Malabry Cedex, France Institut Charles Gerhardt Montpellier, UMR CNRS 5253, Universit e Montpellier 2, 34095 Montpellier cedex 05, France EaStChem School of Chemistry, University of St. Andrews Purdie Building, St Andrews, KY16 9ST U.K.

Metal-organic frameworks in biomedicine.

RATIONALE AND OBJECTIVES The authors evaluate MS-325, a new albumin-targeted magnetic resonance imaging (MRI) contrast agent, for its pharmacokinetics, biodistribution, and elimination characteristics in multiple animal species. METHODS Studies were performed in rats, rabbits, and nonhuman primates at intravenous doses ranging from 0.025 to 0.20 mmol/kg. Concentrations of MS-325 in blood, urine, feces, and organs were determined using gadolinium-153-labeled MS-325 and gamma counting or by using non-labeled MS-325 and inductively coupled plasma atomic emission spectrometry. RESULTS In rabbits and nonhuman primates, MS-325 is approximately 85% to 95% bound to serum proteins and, as a result, exhibits low volume of distribution (Vd) values, 0.11 to 0.14 L/kg, and a long elimination half-life (Te1/2), 2 to 3 hours. Some dose-dependence in the parameters is apparent in rabbits. MS-325 is eliminated primarily through the renal system in non-human primates. In contrast, the behavior of MS-325 in rats is different, exhibiting increased biliary excretion, a larger Vd value, and a shorter Te1/2. CONCLUSIONS The pharmacokinetics and elimination profile of MS-325, including vascular retention and renal excretion, are favorable for use in humans as an intravascular contrast agent for MRI.

Preclinical evaluation of the pharmacokinetics, biodistribution, and elimination of MS-325, a blood pool agent for magnetic resonance imaging.

Clinically relevant relaxivity enhancement of a magnetic resonance imaging (MRI) contrast agent has been achieved by using prodrug Gd3+ complexes (see picture, DTPA=diethylenetriaminepentaaceto). Enzymatic cleavage of lysine residues from the prodrug exposes a group that has a high affinity to human serum albumin and promotes enhanced relaxivity, thus enabling the detection of targets at submicromolar concentrations.

Enzyme-Activated Gd3+ Magnetic Resonance Imaging Contrast Agents with a Prominent Receptor-Induced Magnetization Enhancement

Preparation and water relaxation properties of proteins labeled with paramagnetic metal chelates.

MS-325: a small-molecule vascular imaging agent for magnetic resonance imaging.

To assess the effectiveness of an intravascular contrast agent, MS-325, for enhancing the vascular signal in coronary MR angiograms, six minipigs were studied using a three-dimensional, gradient-echo sequence with retrospective respiratory gating. To suppress the myocardial signal, preparatory RF pulses were applied before data acquisition. With the administration of MS-325, the blood signal-to-noise ratio increased by 97-276%, depending on the region of interest in which the blood signal was measured and the precontrast imaging sequence structures. The blood/myocardium contrast-to-noise ratio also significantly increased. High-resolution images (0.58 x 0.58 x 1 mm3) obtained from postmortem pig hearts demonstrated the potential delineation of coronary arteries with MS-325. In conclusion, this study supports further evaluation of the utility of MS-325 in improving coronary MR angiography in humans.

Randall B. Lauffer

Papers

Preclinical evaluation of the pharmacokinetics, biodistribution, and elimination of MS-325, a blood pool agent for magnetic resonance imaging.

Enzyme-Activated Gd3+ Magnetic Resonance Imaging Contrast Agents with a Prominent Receptor-Induced Magnetization Enhancement

Preparation and water relaxation properties of proteins labeled with paramagnetic metal chelates.

MS-325: a small-molecule vascular imaging agent for magnetic resonance imaging.

Three‐dimensional MRI of coronary arteries using an intravascular contrast agent