| POLYMERS Vol.62 No.6 |
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COVER STORY
Molecular Imaging and Polymer |
| COVER STORY: Highlight Reviews |
| Ultrasound Theranostics | Kazuo MARUYAMA |
| <Abstract> The combination of ultrasound and bubble liposomes is a good tool for “theranostics” due to their multi-potency for diagnostics with sonography and for therapeutics with induced cavitation. Keywords: Ultrasound / Theranostics / Micro Bubble / Liposome / DDS / Gene Delivery |
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| Development of Tumor Imaging Agents Consisting of Amphiphilic Block Copolymers | Koji MIKI |
| <Abstract> Advances in diagnostic instrumentation and analytical technique in tumor detection are accelerating the development of tumor imaging agents including polymeric self-assemblies consisting of amphiphilic block copolymers. Tumor-specific accumulation of polymeric self-assemblies via passive tumor-targeting is one of practical benefits to obtain high-contrast images. To detect small-sized tumors, the performance of polymeric imaging agents has been improved by designing the structures of amphiphilic block copolymers and their self-assemblies precisely. In this review, an overview of amphiphilic block copolymers for tumor detection utilizing magnetic resonance imaging, positron emission tomography, computed tomography, ultrasonography, near-infrared fluorescence imaging, and photoacoustic imaging will be presented. Keywords: Tumor Imaging / Contrast Agent / Polymeric Self-Assembly / Amphiphilic Block Copolymer |
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| Detection and Imaging of Protein Activity with Dynamic Self-Assembling Turn-on Nanoprobes | Yousuke TAKAOKA, Itaru HAMACHI |
| <Abstract> Specific detection or imaging protein biomarkers in cells or in vivo potentially contributes to basic biological research and therapeutic/diagnostic applications. Recently, several groups have reported unique supramolecular strategies for detection and/or imaging of proteins using self-assembling nanomaterials. Here we focus on these attractive nanomaterials for turn-on sensing and profiling of proteins in live cell, as well as in vitro. Keywords: Protein / 19F-NMR/MRI / Fluorescence / Imaging / Nanoparticle / Supramolecular Chemistry |
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| COVER STORY: Topics and Products |
| Chemical Transmitter Imaging Using Aptamer Sensor | Shinsuke SANDO |
| <Abstract> Nucleic acid aptamer is a functional biopolymer that can bind to target molecules. Because of high affinity and specificity to targets in water, there has been an attention on application of aptamers to biosensors. However, cellular application has been very limited. We have applied fluorescent aptamer sensors for molecular imaging of chemical transmitters, especially those working in brain. The fluorescent aptamer sensor, which was anchored in live cell surfaces, functioned as a biosensor for fluorescence imaging of chemical molecules at the cell surface. By using the cell-surface anchored fluorescent aptamer sensor, we achieved a real-time imaging of chemical transmitter dynamics released from rat astrocyte cells. This approach could expand the research field of aptamer biosensors. Keywords: Fluorescence Imaging / Chemical Sensor / Chemical Transmitter / Aptamer / Cell Surface |
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| Developments of Macromolecular MRI Contrast Agents | Satoru KARASAWA, Noboru KOGA |
| <Abstract> We report herein our approaches using macromolecules and assemblies carrying metal and organic spins as magnetic resonance image (MRI) contrast agents. Core-shell type hyperbranched polymers carrying manganese complexes (HPS200-8-MnDO3A-DEA), and lipophilic urenylbenzene derivatives (EgnCmU-TEMPO) and DNA oligomers incorporated stable organic radical, TEMPO, were prepared as macromolecular MRI contrast agents. A HPS polymer, HPS200-8-MnDO3A-DEA, was evaluated by in vivo MRI measurement and revealed to function as an MRI agent. EgnCmU-TEMPO derivatives having PEG and alkyl chains exhibited LCST phenomena in water and were found to have the relaxivity in response to heat and pH. Furthermore, TEMPO-DNA micelle locating TEMPO near a core of micelle was found to have the relaxivity higher than that for GdDOTA at 42 MHz and 1.0 T. Keywords: MRI Contrast Agents / Maclomolecules / Manganese / TEMPO / Organic Spin / Relaxivity |
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| Development of Nano-Sized Polyion Complex Vesicle “PICsomes” and its Application to Bioimaging and Nano-Physiology | Akihiro KISHIMURA |
| <Abstract> To gain more insights of structural and physicochemical features of sick parts in our body, we need to investigate our body from the nanoscopic viewpoint. Some appropriate tools are required for this purpose, or nano-physiology, particularly to visualize the affected part at the nanoscopic level. Recently, we have developed polyion complex vesicles “PICsomes” mainly based on the electrostatic interaction between oppositely charged block copolymers. Remarkable features of PICsomes were demonstrated, such as unilamellar structure with uniform thickness, tunable size over the range of 100-400 nm, easy loading of water-dispersible materials, semi-permeability, excellent blood circulation in mice, and so on. Detailed biodistribution of PICsomes with different sizes was examined in tumor-bearing mice. Critical size of nanocarriers (～150 nm) discriminating the permeability into normal and tumor tissues was determined by the use of long-circulating PICsomes as a ruler. This result clearly shows potential utility of PICsomes in the filed of “nano-physiology”, considering the compatibility of PICsomes with various bioimaging probes. Keywords: Drug Delivery System / Block Copolymers / Vesicles / Polyion Complexes / Bioimaging / Nano-Physiology |
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| X-Ray CT and MRI Using PEGylated Dendrimers | Chie KOJIMA |
| <Abstract> There are a lot of imaging techniques such as X-ray CT (computed tomography) and MRI (magnetic resonance imaging). Imaging agents with small molecular weight are rapidly excluded from the body, whereas macromolecular imaging agents are more useful. Dendrimers are synthetic globular macromolecules with well-defined structure, multiple terminal groups and inner space. Additionally, polyethylene glycol (PEG) modification to dendrimers is indispensable for biomedical applications. In this paper, X-ray CT imaging and MRI based on PEGylated dendrimers are shown. First, we prepared gold nanoparticle (Au NP)-loaded PEGylated dendrimers for X-ray CT imaging. Interestingly, Au NP has photo-thermogenic property, which is applicable to photothermal therapy. Thus, Au NP-loaded PEGylated dendrimers are useful in both, therapy and diagnosis, named theragnosis. Next, we prepared Gd-chelate-conjugated PEGylated dendrimers. This dendrimer shows higher MR signals than the chelate itself. Blood pool and heart were enhanced by the Gd-chelate-conjugated PEGylated dendrimer. Because some imaging probes can be attached to the dendrimers, dendrimers are potent multimodal imaging agents. Keywords: Dendrimer / PEGylation / X-Ray CT / MRI / In Vivo Imaging |
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| Polymer Science and I: A Personal Account |
| Sometimes We have to Hold Our Ground | Shiki YAGAI |
| <Abstract> From my experience living and working with an Indian student for two months, I learned new discoveries elude us if we compromise our goals. |
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| Front-Line Polymer Science |
| Nanomatrix Structure and Properties of Natural Rubber | Seiichi KAWAHARA |
| <Abstract> Nanomatrix structure, consisting of a dispersoid of a major component and a matrix of a minor component, was formed in natural rubber, after removal of all proteins from the rubber. It was found to be a unique nano-phase separated structure by both field-emission scanning electron microscopy equipped with focused ion beam (FIB-SEM) and transmission electron micro-tomography (TEMT). Dramatic increases in mechanical properties and proton-conductivity were associated with the formation of the nanomatrix structure. Based on the results, the nanomatrix of non-rubber components such as proteins and phospholipids was found to be inherently formed in natural rubber, in which natural rubber particles of about 1μm in average diameter were dispersed. It was proven that the nanomatrix structure played an important role in the outstanding mechanical properties of natural rubber. Some applications of the nanomatrix structure were shown for composites of natural rubber with inorganic fillers. Keywords: Natural Rubber / Nanomatrix Structure / Nanomatrix / Proteins / Phospholipids / Latex / Terminal Units / Graft-Copolymerization |
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