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1.
J Am Chem Soc ; 143(9): 3306-3311, 2021 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-33636078

RESUMO

Octaaryl-substituted bisquinodimethanes (BQDs) with a zigzag structure were designed as redox-switchable molecules that undergo four-electron oxidation to produce tetracationic pentacenes with a doubly twisted structure. In contrast to one-stage four-electron oxidation of BQDs, stepwise two-electron reduction of tetracationic pentacenes occurs to give dicationic anthracenes and then the original BQDs, step-by-step. Since both tetracations and dications exhibit near-infrared (NIR) absorptions (-1400 nm) based on an intramolecular charge-transfer interaction, changes in not only their structures but also their UV-vis-NIR spectra can be controlled by redox stimuli. In this Communication, we present an unprecedented one-step π-extension to pentacene from non-fused benzene rings by oxidation, and subsequent two-stage deannulation to benzene rings via anthracene upon reduction. All structures were determined by single-crystal X-ray analyses, and their properties were characterized by spectroscopic and theoretical studies.

2.
Chem Asian J ; 15(7): 1147-1155, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32030909

RESUMO

When the 1,1,4,4-tetraanilinobutadiene skeleton is attached with two halogenated aryl units at the 2,3-positions, they undergo facile two-electron oxidation to give stable dicationic dyes which exhibit a near-infrared (NIR) absorption whereas the neutral dienes show only pale color. Therefore, a distinct electrochromic response with an absorption change in the NIR region is achieved, which is attracting considerable recent attention from the viewpoint of bioimaging. Herein, we demonstrate that the redox potentials of the 1,1,4,4-tetraanilinobutadiene can be precisely controlled by the donating properties of the amino group on the aniline unit as well as the number of halogen atoms on the aryl units at 2,3-positions on the butadiene. In contrast, the NIR absorption bands mainly depend on the number of halogen atoms irrespective to the donating properties of aniline unit. Thus, the hexaarylbutadiene skeleton is proven to be a versatile scaffold to develop less-explored organic NIR electrochromic materials, whose redox and spectroscopic properties can be finely tuned by modifying/attaching the proper substituents.

3.
Nat Commun ; 11(1): 446, 2020 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-31974383

RESUMO

Afterglow luminescent probes with high signal-to-background ratio show promise for in vivo imaging; however, such probes that can be selectively delivered into target sites and switch on afterglow luminescence remain limited. We optimize an organic electrochromic material and integrate it into near-infrared (NIR) photosensitizer (silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) and (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]) containing nanoparticles, developing an H2S-activatable NIR afterglow probe (F12+-ANP). F12+-ANP displays a fast reaction rate (1563 ± 141 M-1 s-1) and large afterglow turn-on ratio (~122-fold) toward H2S, enabling high-sensitivity and -specificity measurement of H2S concentration in bloods from healthy persons, hepatic or colorectal cancer patients. We further construct a hepatic-tumor-targeting and H2S-activatable afterglow probe (F12+-ANP-Gal) for noninvasive, real-time imaging of tiny subcutaneous HepG2 tumors (<3 mm in diameter) and orthotopic liver tumors in mice. Strikingly, F12+-ANP-Gal accurately delineates tumor margins in excised hepatic cancer specimens, which may facilitate intraoperative guidance of hepatic cancer surgery.


Assuntos
Carcinoma Hepatocelular/diagnóstico por imagem , Sulfeto de Hidrogênio/análise , Neoplasias Hepáticas/diagnóstico por imagem , Substâncias Luminescentes/química , Imagem Molecular/métodos , Animais , Neoplasias Colorretais/sangue , Cistationina beta-Sintase/análise , Cistationina beta-Sintase/metabolismo , Cistationina gama-Liase/análise , Cistationina gama-Liase/metabolismo , Células Hep G2 , Humanos , Sulfeto de Hidrogênio/sangue , Sulfeto de Hidrogênio/química , Neoplasias Hepáticas/sangue , Neoplasias Hepáticas Experimentais/diagnóstico por imagem , Substâncias Luminescentes/síntese química , Camundongos Endogâmicos BALB C , Nanopartículas/química , Fármacos Fotossensibilizantes/química , Polímeros/química , Compostos de Vinila/química , Ensaios Antitumorais Modelo de Xenoenxerto
4.
J Xray Sci Technol ; 21(2): 147-59, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23694908

RESUMO

In proton density-weighted (PDW) MR imaging, the patterns of signal intensity vary depending on the imaged material, and change with the flip angle (FA) applied to the imaged material. The correlation between the pre-determined FA and the actual FA applied to imaged objects was investigated using 4 types of phantoms having different dielectric properties. PDW images were acquired using the spin-echo (SE) method and different pre-determined FA. Dependency of the signal intensity distribution in the phantom on the pre-determined FA differed among phantoms: patterns for water and 0.402 w/w% saline solution phantoms changed with the pre-determined FA, whereas those for olive oil and 4.02 w/w% saline solution phantoms were barely affected by the pre-determined FA. Causes of these phenomena were considered to be the differences between the pre-determined FA and the actual FA among the phantoms; differences were also influenced by the positioning of the phantom. Our study showed that the actual FA in the phantom is greater than the pre-determined FA in high permittivity media, whereas it is reduced by an increased conductivity of the media.


Assuntos
Condutividade Elétrica , Imagem por Ressonância Magnética/métodos , Modelos Teóricos , Processamento de Sinais Assistido por Computador , Campos Eletromagnéticos , Processamento de Imagem Assistida por Computador , Imagens de Fantasmas
5.
Med Phys ; 40(3): 032303, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23464335

RESUMO

PURPOSE: A 3.0-T MRI phantom (called the CAGN-3.0T phantom) having human-equivalent relaxation times and human-equivalent conductivity was developed. METHODS: The ingredients of the phantom are carrageenan (as a gelatinizer), agarose (as a T2-relaxation modifier), GdCl3 (as a T1-relaxation modifier), NaCl (as a conductivity modifier), and NaN3 (as an antiseptic). Numerous samples with varying concentrations of agarose, GdCl3, and NaCl were prepared, and T1 and T2 values were measured using 3.0-T MRI. RESULTS: The T1 values of the CAGN-3.0T phantom were unaffected by NaCl, while the T2 values were only slightly affected. Based on the measured data, empirical formulae were devised to express the relationships between the concentrations of agarose, GdCl3, and NaCl and the relaxation times. The formula for expressing the conductivity of the CAGN-3.0T phantom was obtained. CONCLUSIONS: By adjustments to the concentrations of agarose, GdCl3, and NaCl, the relaxation times and conductivity of almost all types of human tissues can be simulated by CAGN-3.0T phantoms. The phantoms have T1 values of 395-2601 ms, T2 values of 29-334 ms, and conductivity of 0.27-1.26 S/m when concentrations of agarose, GdCl3, and NaCl are varied from 0 to 2.0 w/w%, 0 to 180 µmol/kg, and 0 to 0.7 w/w%, respectively. The CAGN-3.0T phantom has sufficient strength to replicate the torso without using reinforcing agents, and can be cut with a knife into any shape.


Assuntos
Imagem por Ressonância Magnética/instrumentação , Imagens de Fantasmas , Impedância Elétrica , Gadolínio/química , Humanos , Sefarose/química , Cloreto de Sódio/química
6.
Acta Med Okayama ; 66(3): 203-11, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22729100

RESUMO

Magnetic resonance imaging (MRI) visualization of metallic stent lumens is possible if the stent structure counteracts eddy currents in the lumen induced by the radio frequency magnetic field, B(1). To examine the effectiveness of various stent designs in counteracting eddy currents, we anchored eight copper stent models and 2 commercially available nickel-titanium alloy (Nitinol) stents in a gel phantom, perpendicular or parallel to the direction of B(1). A mesh stent lumen showed hypointensity irrespective of its alignment relative to B(1). A solenoid stent lumen showed hypointensity with the stent axis parallel to B(1), but it had the same signal intensity as outside the lumen when perpendicular to B(1). A Moebius stent lumen showed no signal reduction, irrespective of alignment relative to B(1). Lumens of the commercially available stents showed hypointensity regardless of alignment relative to B(1). Computer simulation revealed that the signal intensities of the stents corresponded to magnetic flux densities of B(1) in the stents, which are modified by the structure of the stent. While in vivo MRI viewing of a Moebius stent lumen is likely possible regardless of axis alignment, inherent structural weakness may be problematic. As a more practical choice, the solenoid stent is easier to manufacture and generates no hypointensive signal when the axis is parallel to B(0).


Assuntos
Imagem por Ressonância Magnética , Stents , Simulação por Computador , Humanos , Campos Magnéticos , Ondas de Rádio
7.
Med Phys ; 38(11): 6336-42, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22047398

RESUMO

PURPOSE: A 3.0-T MRI phantom having human-tissue-equivalent relaxation times was developed. METHODS: The ingredients of the phantom are carrageenan (for gelatinization), GdCl(3) (as a T(1)-relaxation modifier), agarose (as a T(2)-relaxation modifier), and NaN(3) (as an antiseptic agent). Numerous samples with varying concentrations of GdCl(3) and agarose were prepared, and T(1) and T(2) were measured using 3.0-T MRI. RESULTS: Relaxation times of the phantom samples ranged from 395 to 2601 ms for T(1) values and 29 to 334 ms for T(2) values. Based on the measured results, empirical formulae were devised to express the relationships between the concentrations of relaxation modifiers and relaxation times. CONCLUSIONS: Adjustment of GdCl(3) and agarose concentrations allows arbitrary setting of relaxation times, and the creation of a phantom that can mimic relaxation times of human-tissue. Carrageenan is considered the most suitable as a gelling agent for an MRI phantom, as it permits the relatively easy and inexpensive production of a large phantom such as for the human torso, and which can be easily shaped with a knife.


Assuntos
Imagem por Ressonância Magnética/métodos , Imagens de Fantasmas , Carragenina , Gráficos por Computador , Humanos , Sefarose , Fatores de Tempo
8.
Magn Reson Med Sci ; 7(3): 131-40, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18827456

RESUMO

PURPOSE: We conceived a 2-stage heating method to dissolve the ingredients of magnetic resonance (MR) imaging phantoms to overcome issues of uneven quality in conventional MR imaging phantoms, and we evaluated uniformity and the reproducibility of our method. METHODS: We used a 3-liter capacity, column-shaped, enamel-coated porcelain container to produce a muscle-equivalent phantom (diameter, 160 mm; height, 100 mm; volume, 2 liters). The phantom contained: 1) carrageenan as a gelling agent; 2) agarose as a T2 modifier; 3) GdCl3 as a T1 modifier; 4) NaN3 as an antiseptic; and 5) distilled water. We applied both direct heating and 2-stage heating of pre-soaked materials. We placed powdered materials directly into hot water for direct heating but soaked them in water one day before use (post-swelling) in 2-stage heating. The materials in the container were melted in a silicone oil bath of 120 or 140 degrees C under various conditions, then allowed to gel by natural cooling. We observed the resulting gel phantoms macroscopically using a CCD camera and evaluated their uniformity by microscopy and MR imaging. RESULTS: We found it necessary to raise the temperature inside the phantom to 100.0 degrees C, to produce a uniform gel with stable homogeneity and few bubbles. Use of an enamel-coated porcelain container required setting the temperature of the oil bath at 140 degrees C. CONCLUSION: A uniform and reproducible human tissue-equivalent phantom with few bubbles can be manufactured using our 2-stage heating method, which employs pre-soaking in a silicone oil bath at 140 degrees C for 30 min. We then added the swollen carrageenan to the agarose solution, which heating the temperature to 140 degrees C for 30 min while continuously stirring at 120 rpm, following with natural cooling.


Assuntos
Desenho de Equipamento , Análise de Falha de Equipamento , Imagem por Ressonância Magnética/instrumentação , Imagens de Fantasmas , Calefação/métodos , Controle de Qualidade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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