Introduction to Transparency

Soga, Kohei

doi:10.1007/978-981-15-9627-8_1

Cited by 7 publications

(9 citation statements)

References 18 publications

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“…Compared with other modalities of anatomical and molecular imaging, such as X-ray, magnetic resonance imaging (MRI), positron emission tomography, single-photon emission computed tomography [15], and ultrasonography [16], fluorescence imaging has the advantages of no ionizing radiation exposure as well as high sensitivity and temporal resolution. Bio-applications of fluorescence imaging are hampered mainly by the limitations of observation depth owing to the effects of light scattering and absorption by biological tissues [17,18]. Although it is difficult to obtain pathophysiological information at the whole-body level using visible light (wavelength range of 380−700 nm) owing to its limited biological transparency of less than 2−3 mm, near-infrared (NIR) light (wavelength range of 700−2500 nm) is being used for deep in vivo imaging owing to its high transparency in biological tissues [18].…”

Section: Near-infrared Fluorescence Materialsmentioning

confidence: 99%

“…Bio-applications of fluorescence imaging are hampered mainly by the limitations of observation depth owing to the effects of light scattering and absorption by biological tissues [17,18]. Although it is difficult to obtain pathophysiological information at the whole-body level using visible light (wavelength range of 380−700 nm) owing to its limited biological transparency of less than 2−3 mm, near-infrared (NIR) light (wavelength range of 700−2500 nm) is being used for deep in vivo imaging owing to its high transparency in biological tissues [18]. For example, fluorescent dyes, such as indocyanine green (ICG) and methylene blue, which work in the NIR-I wavelength range (700−900 nm), have been clinically applied as contrast agents for blood and lymphatic vessels [19,20]; however, their observation depth is still less than 10 mm.…”

Section: Near-infrared Fluorescence Materialsmentioning

confidence: 99%

“…For example, fluorescent dyes, such as indocyanine green (ICG) and methylene blue, which work in the NIR-I wavelength range (700−900 nm), have been clinically applied as contrast agents for blood and lymphatic vessels [19,20]; however, their observation depth is still less than 10 mm. On the other hand, in the >1000 nm (over-thousand-nanometer: OTN) NIR region, even though the optical absorption owing to water molecular vibration is larger than that in the conventional NIR-I region, the reduction in scattering by biological tissues [21,22] improves the observation depth to several centimeters [18].…”

Section: Near-infrared Fluorescence Materialsmentioning

confidence: 99%

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Controlling Molecular Dye Encapsulation in the Hydrophobic Core of Core–Shell Nanoparticles for In Vivo Imaging

Umezawa

Ueya²,

Ichihashi

et al. 2023

Biomedical Materials & Devices

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Polymeric nanoparticles with a hydrophobic core are valuable biomedical materials with potential applications in in vivo imaging and drug delivery. These materials are effective at protecting vulnerable molecules, enabling them to serve their functions in hydrophilic physiological environments; however, strategies that allow the chemical composition and molecular weight of polymers to be tuned, forming nanoparticles to control the functional molecules, are lacking. In this article, we review strategies for designing core–shell nanoparticles that enable the effective and stable encapsulation of functional molecules for biomedical applications. IR-1061, which changes its optical properties in response to the microenvironment are useful for in vitro screening of the in vivo stability of polymeric nanoparticles. An in vitro screening test can be performed by dispersing IR-1061-encapsulated polymer nanoparticles in water, saline, buffer solution, aqueous protein solution, etc., and measuring the absorption spectral changes. Through the screening, the effects of the polarity, molecular weight, and the chiral structure of polymers consisting of polymer nanoparticles on their stability have been revealed. Based on the findings presented here, more methodologies for the effective application of various biomolecules and macromolecules with complex high-dimensional structures are expected to be developed.

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Section: Near-infrared Fluorescence Materialsmentioning

confidence: 99%

Section: Near-infrared Fluorescence Materialsmentioning

confidence: 99%

Section: Near-infrared Fluorescence Materialsmentioning

confidence: 99%

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Controlling Molecular Dye Encapsulation in the Hydrophobic Core of Core–Shell Nanoparticles for In Vivo Imaging

Umezawa

Ueya²,

Ichihashi

et al. 2023

Biomedical Materials & Devices

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“…Light in the near infrared (NIR) wavelength region exhibits high optical transmittance to living organisms and has been attracting increasing attention for applications in biomedical photonics. With a specific focus on this region ever since 2005, the authors have been developing NIR-emitting probes for biomedical photonics, such as fluorescence bioimaging, photodynamic therapy, and thermometry [ 1 ]. NIR light, as a photon, has a smaller amount of energy than that in visible light, resulting in narrow energy separations between an excited state and a ground state in optical transitions of the luminescence systems.…”

Section: Design Basics Of Near Infrared Fluorescent Nanostructurementioning

confidence: 99%

“…For bioimaging, organic dyes, quantum dot-, carbon nanotube-, and trivalent lanthanide (Ln 3+ )-containing inorganic nanoparticles are the major phosphors that emit NIR light [ 1 ]. Our recent review on the design of fluorescent materials with Ln 3+ ions discussed the thermal interaction between Ln 3+ ions, as luminescence centers, and surrounding atoms, ions, and molecules [ 2 ].…”

Section: Design Basics Of Near Infrared Fluorescent Nanostructurementioning

confidence: 99%

Near Infrared Fluorescent Nanostructure Design for Organic/Inorganic Hybrid System

Okubo¹,

Umezawa²,

Soga³

2021

Biomedicines

Self Cite

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Near infrared (NIR) light offers high transparency in biological tissue. Recent advances in NIR fluorophores including organic dyes and lanthanide-doped inorganic nanoparticles have realized the effective use of the NIR optical window for in vivo bioimaging and photodynamic therapy. The narrow energy level intervals used for electronic transition that involves NIR light, however, give rise to a need for guidelines for reducing heat emission in luminescence systems, especially in the development of organic/inorganic hybrid structures. This review presents an approach for employing the polarity and vibrational energy of ions and molecules that surround the luminescence centers for the development of such hybrid nanostructures. Multiphonon relaxation theory, formulated for dealing with heat release in ionic solids, is applied to describe the vibrational energy in organic or molecular systems, referred to as phonon in this review, and we conclude that surrounding the luminescence centers either with ions with low vibrational energy or molecules with small chemical polarity is the key to bright luminescence. NIR photoexcited phosphors and nanostructures in organic/inorganic mixed systems, designed based on the guidelines, for photodynamic therapy are reviewed.

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Temperature imaging inside fluid devices using a ratiometric near infrared (NIR-II/III) fluorescent Y2O3: Nd3+, Yb3+, Er3+ nanothermometer

Umezawa,

Haraguchi,

Sugawara

et al. 2024

ANAL. SCI.

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Luminescence thermometry is a non-contact method that can measure surface temperatures and the temperature of the area where the fluorescent probe is located, allowing temperature distribution visualizations with a camera. Ratiometric fluorescence thermometry, which uses the intensity ratio of fluorescence peaks at two wavelengths with different fluorescence intensity dependencies, is an excellent method for visualizing temperature distributions independent of the fluorophore spatial concentration, excitation light intensity and absolute fluorescence intensity. Herein, Nd3+/Yb3+/Er3+-doped Y2O3 nanomaterials with a diameter of 200 nm were prepared as phosphors for temperature distribution measurement of fluids at different temperatures. The advantages of this designed fluorescent material include non-aggregation in water and the fact that its near-infrared (NIR) fluorescence excitation (808 nm) is not absorbed by water, thereby minimizing sample heating upon irradiation. Under optical excitation at 808 nm, the ratio of the fluorescence intensities of Yb3+ (IYb; 975 nm) and Er3+ (IEr; 1550 nm), which exhibited different temperature responses, indicated the temperature distribution inside the fluid device. Thus, this technique using Nd3+/Yb3+/Er3+-doped Y2O3 is expected to be applied for temperature distribution mapping analysis inside fluidic devices as a ratiometric NIR fluorescence thermometer, which is unaffected by laser-induced heating. Graphical abstract

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Introduction to Transparency

Cited by 7 publications

References 18 publications

Controlling Molecular Dye Encapsulation in the Hydrophobic Core of Core–Shell Nanoparticles for In Vivo Imaging

Controlling Molecular Dye Encapsulation in the Hydrophobic Core of Core–Shell Nanoparticles for In Vivo Imaging

Near Infrared Fluorescent Nanostructure Design for Organic/Inorganic Hybrid System

Temperature imaging inside fluid devices using a ratiometric near infrared (NIR-II/III) fluorescent Y2O3: Nd3+, Yb3+, Er3+ nanothermometer

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