Keio University · Engineering
Professor Yuki Hiruta's research lab specializes in the design and development of advanced fluorescent probes and stimuli-responsive materials for biomedical and analytical applications. The lab focuses on creating smart polymers and optical sensors that respond to physiological stimuli such as temperature, pH, and specific metal ions (e.g., Mg²⁺, Ag⁺, Hg²⁺), with an emphasis on ratiometric and near-infrared (NIR) fluorescence for high-contrast, multi-color imaging. Key research directions include the synthesis of selective, stable, and biocompatible probes for real-time monitoring of intracellular dynamics and the engineering of functional materials for applications in drug delivery and high-performance liquid chromatography (HPLC).
Figures are computed from collected data and may differ slightly.
Poly(<i>N</i>-isopropylacrylamide) (PNIPAAm)-based temperature-responsive fluorescence polymer probes were developed using radical polymerization, with 3-mercaptopropionic acid as the chain-transfer agent, followed by activation of terminal carboxyl groups with <i>N</i>-hydroxysuccinimide and reaction with 5-aminofluorescein (FL). The lower critical solution temperatures (LCSTs) of the resulting fluorescent polymer probes differed depending on the copolymer composition, and had a sharp phase-tra
Two distyryl-BODIPY-based NIR red-shifting ratiometric fluorescent probes are reported: KBHR-1 for pH and KBAHgR-1 for Ag(+) and Hg(2+). KBHR-1 showed a red-shifting ratiometric response to pH in the NIR region. The identical fluorophore core structure applied to KBAHgR-1 with a different recognition moiety resulted in a ratiometric response to Ag(+) and Hg(2+) in the NIR region.
The magnesium ion (Mg<sup>2+</sup>) is an essential cation to maintain proper cellular activities. To visualize the dynamics and functions of Mg<sup>2+</sup>, there is a great need for the development of Mg<sup>2+</sup>-selective fluorescent probes. However, conventional Mg<sup>2+</sup> fluorescent probes are falling behind in low selectivity and poor fluorescence color variation. In this report, to make available a distinct color window for multi-color imaging, we designed and synthesized highl
Long-term stable ratiometric fluorescent optical pH sensors (optodes) based on double sol–gel silica layers are prepared with the first layer embedding two types of quantum dots (QDs) and the second layer embedding light-absorbing pH indicators. The sensors are fabricated by a simple general sol–gel spin-coating method. The resulting double-layer pH optodes are designed as having long Stokes shift as well as ratiometric fluorescence emission response to pH in aqueous solutions of varying pH valu
Dual responsive polymeric micelle enabled selective intracellular uptake with thermal stimulation and effective release of doxorubicin at acidic endosomal pH.
Temperature-responsive polymers incorporating molecular-recognition sites were developed as stationary phases for high-performance liquid chromatography (HPLC). The grafted stationary phases consisted of functional copolymers composed of N-isopropylacrylamide (NIPAAm) and N-acryloyl aromatic amino acid methyl esters, i.e., phenylalanine and tryptophan methyl esters (Phe-OMe and Trp-OMe). Three novel temperature-responsive polymers, P(NIPAAm-co-Phe-OMe5), P(NIPAAm-co-Phe-OMe10), and P(NIPAAm-co-T
Bioluminescence (BL) imaging, which utilizes light emitted through the enzymatic reaction of luciferase oxidizing its substrate luciferin, enables sensitive and noninvasive monitoring of life phenomena. Herein, we developed a series of caged furimazine (FMZ) derivatives by introducing a protective group at the C-3 position and a hydroxy group at the C-6 phenyl ring to realize long-term live-cell BL imaging based on the NanoLuc (NLuc)/NanoKAZ (NKAZ)-FMZ system. The membrane permeability and cytot
Even using the same homo poly(<italic>N</italic>-isopropylacrylamide) immobilized silica beads as stationary phases, terminal functional group and chain length significantly affected temperature-dependent elution behavior of steroids.
Bioluminescence is a powerful imaging modality for monitoring biological phenomena both in vitro and in vivo. Bioluminescence imagin (BLI) is becoming a seamless imaging technology covering the range from cells to organs of small animals. Long-term imaging at the single cell level would lead to a true understanding of the dynamics of life phenomena. This work presents a long-term single cell bioluminescence imaging technology accomplished with C-3 position protected furimazines (FMZs), a CTZ ana
A prediction model for cloud point was built by a combination of materials informatics and chemical insight.
Poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) is a water-soluble polymer in which multiple short ethylene glycol (EG) chains are grafted along the hydrophobic methyl methacrylate backbone. We investigated whether POEGMA could be used as a drug carrier for tumor diagnosis. For this purpose, we synthesized POEGMA derivatives with different molecular weights (11, 21, and 30 kDa) and EG side chain lengths, and labeled them with radioisotopes (indium-111; 111In) or fluorescence dyes
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