Near-infrared fluorescence (NIRF) thermometry is an emerging method for the noncontact measurement of deep temperatures. Fluorescence-lifetime-based methods are effective because they are unaffected by optical loss due to excitation or detection paths. Moreover, the physiological changes in body temperature in deep tissues and their pharmacological effects are yet to be fully explored.
View Article and Find Full Text PDFLuminescence 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, Nd/Yb/Er-doped YO nanomaterials with a diameter of 200 nm were prepared as phosphors for temperature distribution measurement of fluids at different temperatures.
View Article and Find Full Text PDFFatty acids play various physiological roles owing to their diverse structural characteristics, such as hydrocarbon chain length (HCL) and degree of saturation (DS). Although the distribution of fatty acids in biological tissues is associated with lipid metabolism, in situ imaging tools are still lacking for HCL and DS. Here, we introduce a framework of near-infrared (1000-1400 nm) hyperspectral label-free imaging with machine learning analysis of the fatty acid HCL and DS distribution in the liver at each pixel, in addition to the previously reported total lipid content.
View Article and Find Full Text PDFJ Biomed Mater Res B Appl Biomater
January 2024
Micelles have been extensively used in biomedicine as potential carriers of hydrophobic fluorescent dyes. Their small diameters can potentially enable them to evade recognition by the reticuloendothelial system, resulting in prolonged circulation. Nevertheless, their lack of stability in physiological environments limits the imaging utility of micelles.
View Article and Find Full Text PDFSignificance: Determining the extent of gastric cancer (GC) is necessary for evaluating the gastrectomy margin for GC. Additionally, determining the extent of the GC that is not exposed to the mucosal surface remains difficult. However, near-infrared (NIR) can penetrate mucosal tissues highly efficiently.
View Article and Find Full Text PDFWe developed a small MRI/NIR-II probe to target HER2 (tetanucleotide) breast cancer cells. The probe is composed of PLGA--PEG micelles encapsulated NIR-II, and Gd-DOTA is conjugated at the border of PLGA/PEG. Herceptin was then conjugated to carboxyl residues of PLGA--PEG chains.
View Article and Find Full Text PDFMultimodal imaging is attractive in biomedical research because it can provide multidimensional information about objects that individual techniques cannot accomplish. In particular, combining over one-thousand-nanometer near-infrared (OTN-NIR) fluorescence and magnetic resonance (MR) imaging is promising for detecting lesions with high sensitivity and structural information. Herein, we describe the development of a bimodal OTN-NIR/MRI probe from gadolinium-tetraazacyclododecanetetraacetic acid (Gd-DOTA) conjugated poly(lactic--glycolic acid)--poly(ethylene glycol) copolymer (PLGA--PEG) micelle encapsulated IR-1061 at two different locations.
View Article and Find Full Text PDFThaumatin is an intensely sweet-tasting protein. Its sweetness persists when heated under acidic conditions, but disappears when heated at a pH above 7.0.
View Article and Find Full Text PDFOver-thousand-nanometer (OTN) near-infrared (NIR) fluorophores are useful for biological deep imaging because of the reduced absorption and scattering of OTN-NIR light in biological tissues. IR-1061, an OTN-NIR fluorescent dye, has a hydrophobic and cationic backbone in its molecular structure, and a non-polar counter ion, BF . Because of its hydrophobicity, IR-1061 needs to be encapsulated in a hydrophobic microenvironment, such as a hydrophobic core of polymer micelles, shielded with a hydrophilic shell for bioimaging applications.
View Article and Find Full Text PDFOrganic molecules that emit near-infrared (NIR) fluorescence at wavelengths above 1000 nm, also known as the second NIR (NIR-II) biological window, are expected to be applied to optical imaging of deep tissues. The study of molecular states of NIR-II dye and its optical properties are important to yield well-controlled fluorescent probes; however, no such study has been conducted yet. Among the two major absorption peaks of the NIR-II dye, IR-1061, the ratio of the shorter wavelength (900 nm) to the longer one (1060 nm) increased with an increase in the dye concentration in tetrahydrofuran, suggesting that the 900 nm peak is due to the dimer formation of IR-1061.
View Article and Find Full Text PDFThe refraction of fluorescence from the inside of a sample at the surface results in fluctuations in fluorescence computed tomography (CT). We evaluated the influence of the difference in refractive index (RI) between the sample body and the surroundings on fluorescence CT results. The brightest fluorescent point is away from the correct point on the tomograms owing to the refraction.
View Article and Find Full Text PDFMultimodal imaging can provide multidimensional information for understanding concealed microstructures or bioprocesses in biological objects. The combination of over-1000 nm near-infrared (OTN-NIR) fluorescence imaging and magnetic resonance (MR) imaging is promising in providing high sensitivity and structural information of lesions. This combination can be facilitated by the development of an imaging probe.
View Article and Find Full Text PDFWe designed a biodegradable hybrid nanostructure for near-infrared (NIR)-induced photodynamic therapy (PDT) using an ultrasmall upconversion (UC) phosphor (β-NaYF:Yb, Er nanoparticle: NPs) and a hydrocarbonized rose bengal (CRB) dye, a hydrophobized rose bengal (RB) derivative. The UC-NPs were encapsulated along with CRB in the hydrophobic core of the micelle composed of poly(ethylene glycol) (PEG)--poly(ε-caprolactone) (PCL). The UC-NPs were well shielded from the aqueous environment, owing to the encapsulation in the hydrophobic PCL core, to efficiently emit green UC luminescence by avoiding the quenching by the hydroxyl groups.
View Article and Find Full Text PDFNear 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.
View Article and Find Full Text PDFIn this study, a laparoscopic imaging device and a light source able to select wavelengths by bandpass filters were developed to perform multispectral imaging (MSI) using over 1000 nm near-infrared (OTN-NIR) on regions under a laparoscope. Subsequently, MSI (wavelengths: 1000-1400 nm) was performed using the built device on nine live mice before and after tumor implantation. The normal and tumor pixels captured within the mice were used as teaching data sets, and the tumor-implanted mice data were classified using a neural network applied following a leave-one-out cross-validation procedure.
View Article and Find Full Text PDFRare-earth-doped nanoparticles (NPs), such as NaGdF nanocrystals doped with light-emitting rare earth ions, are promising bimodal probes that allow the integration of over 1000 nm near-infrared (OTN-NIR; NIR-II/III) fluorescence imaging and magnetic resonance imaging (MRI) of live bodies. A precise control of the particle size is the key factor for achieving a high signal-to-noise ratio in both NIR fluorescence and MR images and for regulating their function in the body. In this study, size-controlled NaGdF:Yb, Er NPs prepared by stepwise crystal growth were used for in vivo bimodal imaging.
View Article and Find Full Text PDFLipid distribution in the liver provides crucial information for diagnosing the severity of fatty liver and fatty liver-associated liver cancer. Therefore, a noninvasive, label-free, and quantitative modality is eagerly anticipated. We report near-infrared hyperspectral imaging for the quantitative visualization of lipid content in mouse liver based on partial least square regression (PLSR) and support vector regression (SVR).
View Article and Find Full Text PDFThe diagnosis of gastrointestinal stromal tumor (GIST) using conventional endoscopy is difficult because submucosal tumor (SMT) lesions like GIST are covered by a mucosal layer. Near-infrared hyperspectral imaging (NIR-HSI) can obtain optical information from deep inside tissues. However, far less progress has been made in the development of techniques for distinguishing deep lesions like GIST.
View Article and Find Full Text PDFOne of the most commonly used near infrared (NIR) dyes is indocyanine green (ICG), which has been extensively used for NIR bioimaging, photothermal and photodynamic therapy. However, upon excitation this dye can react with molecular oxygen to form singlet oxygen (SO), which can then cleave ICG to form non-fluorescent debris. In order to reduce the reaction between ICG and oxygen, we used energy transfer (ET) between the former and the NIR dye IR-1061.
View Article and Find Full Text PDFArraying individual extracellular vesicles (EVs) on a chip is expected one of the promising approaches for investigating their inherent properties. In this study, we immobilized individual EVs on a surface using a nanopatterned tethering chip-based versatile platform. A microfluidic device was used to ensure soft, reproducible exposure of the EVs over the whole chip surface.
View Article and Find Full Text PDFContactless thermal imaging generally relies on mid-infrared cameras and fluorescence imaging with temperature-sensitive phosphors. Fluorescent thermometry in the near-infrared (NIR) region is an emerging technique for analysing deep biological tissues but still requires observation depth calibration. We present an NIR fluorescence time-gated imaging (TGI) thermometry technology based on fluorescence lifetime, an intrinsic fluorophore time constant unrelated to observation depth.
View Article and Find Full Text PDFOne of the sweetest proteins found in tropical fruits (with a threshold of 50 nM), thaumatin, is also used commercially as a sweetener. Our previous study successfully produced the sweetest thaumatin mutant (D21N), designated hyper-sweet thaumatin, which decreases the sweetness threshold to 31 nM. To investigate why the D21N mutant is sweeter than wild-type thaumatin, we compared the structure of the D21N mutant solved at a subatomic resolution of 0.
View Article and Find Full Text PDFWe present a hybrid nanofabrication technology for realizing single-crystalline metal nanoparticle ensembles, such as trimers, heptamers and periodic arrays; well-suited for nanoplasmonics applications. Top-down engineered nanotemplates result in the deterministic formation of isolated polycrystalline gold islands with precise volume and position, which are transformed into single-crystalline nanoparticles using bottom-up self-assembly based on nanotemplate-guided thermal dewetting.
View Article and Find Full Text PDFAutonomous transport and release of bacterial cells by self-propelled micromotors were achieved. The motors consisted of zinc and platinum hemispheres formed on polystyrene beads and moved as a result of simultaneous redox reactions occurring on both metal ends. The highly negative redox potential of zinc enabled the selection of a wide variety of organic redox compounds as fuels, such as methanol and p-benzoquinone.
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