Publications by authors named "I-Chia Chen"

Article Synopsis
  • Colloidal gold nanoparticles (AuNPs) are critical for chemical sensing and therapeutic applications, necessitating effective surface functionalization for stability in biological environments.
  • Traditional methods use thiol groups for bonding, but these can be complex and not resilient to certain conditions, leading to the exploration of alkyne derivatives as a preferable alternative.
  • The study shows that alkyne derivatives provide easier preparation, higher stability, and better conjugation efficiency, and highlights their effectiveness in detecting hydrogen peroxide and streptavidin proteins.
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In this study, a series of BiTeX (X = Cl, Br, I) photocatalysts were successfully synthesized via a simple hydrothermal method. The synthesis process involved dissolving BiX and Te powder in toluene to identify the most efficient material for photocatalytic activity. The main objective of this approach is to facilitate the conversion of carbon dioxide into sustainable solar fuels, such as alcohols and hydrocarbons, offering an appealing solution to address environmental concerns and energy crises.

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Article Synopsis
  • - The study examined the triplet transitions in various light-emitting materials like rose bengal and several iridium compounds using advanced spectroscopy techniques.
  • - The samples were excited using a 355 nm laser, leading to efficient movement from their singlet to triplet excited states, revealing specific absorption bands corresponding to these transitions.
  • - Distinct absorption bands were identified for each material, with rose bengal showing a band at 9400 cm, while iridium compounds showed bands at around 7500-7700 cm, indicating different contributions from metal-to-ligand charge transfer mechanisms.
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Semiconductor crystals have generally shown facet-dependent electrical, photocatalytic, and optical properties. These phenomena have been proposed to result from the presence of a surface layer with bond-level deviations. To provide experimental evidence of this structural feature, synchrotron X-ray sources are used to obtain X-ray diffraction (XRD) patterns of polyhedral cuprous oxide crystals.

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Nitrite (NO) is one of the common salts in aqueous aerosols, and its photolytic products, nitric oxide (NO) and hydroxyl radical (OH), have potential for use in the oxidation of organic matter, such as dissolved formaldehyde, methanediol (CH(OH)), which is regarded as the precursor of atmospheric formic acid. In this work, the simulation of UVA irradiation in an aqueous mixture of NaNO/CH(OH) was carried out continuous exposure with a 365 nm LED lamp, and the reaction evolutions were probed by and real-time infrared and Raman spectroscopy, which provided multiplexity in the identification of the relevant species and the corresponding reaction evolution. Although performing infrared absorption measurements in aqueous solution seemed impracticable due to the strong interference of water, the multiplexity of the vibrational bands of parents and products in the non-interfered infrared regimes and the conjunction with Raman spectroscopy still make it possible to perform and real-time characterization of the photolytic reaction in the aqueous phase, supplementary to chromatographic approaches.

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Using low-wavenumber Raman spectroscopy in combination with theoretical calculations solid-state density functional theory (DFT)-D3, we studied the vibrational structures and interaction with solvent of poly-l-proline and the oligoproline P12 series. The P12 series includes P12, the positively charged amino acid residue (arginine and lysine) N-terminus proline oligomers RP11 and KP11, and the C-terminus P11R and P11K. We assigned the spring-type phonon mode to 74-76 cm bands for the PPI and PPII conformers and the carbonyl group ring-opening mode 122 cm in the PPI conformer of poly-l-proline.

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The electronic and vibrational structures of trinickel metal string complexes [Ni(dpa)X] (X = Cl, NCS) were investigated using both theoretical calculations and spectroscopic methods. We used the density functional theory (DFT) method B3LYP*-D3, including less exact exchange energy and the van der Waals interaction of metal ions, to obtain the geometries and vibrational structures, which were found to be in excellent agreement with the experimental data. The ground state of Ni(dpa)X is an antiferromagnetic (AF) singlet state, and the next state is a quintet state, which was detected using temperature-dependent Raman spectroscopy under a magnetic field.

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Background/purpose: Pediatric obstructive sleep apnea (OSA) might be a serious cause of neurocognitive deficits, behavioral changes, and craniofacial disharmony in children at very young age with mild type of OSA. This study aims to examine the effect of mild OSA on craniofacial morphology as well as dental arch morphology and characteristics in preschool children.

Materials And Methods: The test group comprised 16 preschool children (11 boys, 5 girls; mean age: 5.

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A method for the catalytic α-arylation of indolin-3-ones was developed. The catalytic system comprising Pd(dba) and PAd was found to be optimal for the transformation. The protocol features broad functional group compatibility in that a range of arylated indoxyl derivatives bearing a fully substituted carbon center was synthesized with high efficiency.

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Covalently circularized nanodiscs using circular membrane scaffold protein (MSP) serve as a suitable membrane mimetic for transmembrane proteins by providing stability and tunability in lipid compositions, providing controllable biological environments for targeted proteins. In this work, monomeric bacteriorhodopsin (mbR) was embedded in lipid nanodiscs of different lipid compositions using negatively charged lipid dioleoyl phosphatidylglycerol (DOPG) and the zwitterion lipid dioleoyl phosphatidylcholine (DOPC), and the events associated with the retinal Schiff base, including the thermal isomerization during the dark adaptation, photoisomerization, and deprotonation, were investigated. The retinal thermal isomerization from all-, 15- to the 13-, 15- configuration during the dark adaptation was accelerated in the DOPG bilayer, whereas the processes in the DOPC bilayer and in Triton X-100 micelles were similar.

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The facet-dependent redox reactions of diruthenium metal-string complexes by gold nanoparticles (AuNPs) are explored by using the surface-enhanced Raman scattering (SERS) technique. Gold nano-rhombic dodecahedrons (AuRDs), gold nanocubes (AuNCs), and gold octahedrons (AuOhs) with exclusive facets {110}, {100}, and {111}, respectively, were synthesized. These AuNPs linked face-to-face by metal-string complexes RuM(dpa)Cl (dpa = dipyridyl amino, M = Ni, Cu) with chloride axial ligands serve as both SERS substrates and reducing agents in the reactions.

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Objectives: Neurosyphilis, an infectious neuroinflammatory disorder, could cause diverse neuropsychiatric symptoms mimicking disorders of schizophrenia and dementia; hence, it is known as the "chameleon of psychiatry." Here, we present a subject with neurosyphilis with schizophrenic features and share the treatment outcome.

Methods: A 42-year-old single man had schizophrenic-like features and cognitive dysfunction for 1 year.

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Preparing transmembrane protein in controllable lipid bilayers is essential for unravelling the coupling of the environments and its dynamic functions. Monomerized bacteriorhodopsin (mbR) embedded in covalently circularized nanodiscs was prepared with dimyristoylphosphatidylglycerol (DMPG) lipid and circular membrane scaffold proteins of two different sizes, cE3D1 and cΔ H5, respectively. The retinal photoisomerization kinetics and thermodynamic photocycle were examined by femtosecond and nanosecond transient absorption, respectively, covering the time scale from femtoseconds to hundreds of milliseconds.

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Introduction: Sleep problems, neuro-developmental development, and sleep-disordered-breathing (SDB), are reported as more prevalent in premature infants than in full-term infants. We investigated the relationship between neuro-development, and SDB in preterm infants at 24 months corrected age (CA) with a narrow palatal presentation over time.

Methods: We enrolled infants 40 weeks or younger at birth collecting obstetric and birth data.

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Making use of temperature-controlled thiation as a key operation, a simple route to 2-aminothiophenes or thieno[2,3- c]isothiazoles has been newly developed wherein the 2-aminothiophene nucleus was formed through an initial formation of thioamide followed by a 5-exo-dig addition to the tethered alkyne; however, under harsher thermal conditions, excess sulfur-transferring reagents enabled further oxidative thiation to generate the corresponding thieno[2,3- c]isothiazoles.

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Synthesis and characterization of two dodecacopper(I) extended metal atom chains (EMAC) assembled by two hexadentate bis(pyridylamido)amidinate-supported hexacopper(I) string complexes (monomers) via the ligand-unsupported cuprophilicity are described. In addition to short unsupported Cu-Cu contacts, two hexacopper fragments in these two dodecacopper EMACs show a bent conformation based on X-ray crystallography. Compared with their THF-bound hexacopper(I) monomers and protonated ligands, these ligand-unsupported cuprophilic interactions are shown to be weak by Raman spectroscopy.

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We developed a new method by enclosing the complex tris(2-phenylpyridinato-N,C2')Iridium(III), Ir(ppy) with surfactant cetyltrimethylammonium bromide (CATB), coated with a thin layer of silica then bonded to the surface of silver nanoparticle. These samples were used to acquire surface-enhanced Raman scattering (SERS) spectra. The thickness of silica layer was controlled to have efficient phosphorescence quenching and Raman enhancement by metal nanoparticle.

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In this paper, we present a novel charge-free fluorescence-switchable near-infrared (IR) dye based on merocyanine for target specific imaging. In contrast to the typical bathochromic shift approach by extending π-conjugation, the bathochromic shift of our merocyanine dye to the near-IR region is due to an unusual S- cis diene conformer. This is the first example where a fluorescent dye adopts the stable S- cis conformation.

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Herein, the excited-state dynamics of an extended metal atom chain complex, Cr(dpa)Cl (dpa = dipyridylamide), in tetrahydrofuran solution were investigated using femtosecond transient absorption spectroscopy. Upon excitation at a wavelength of 330 nm, two distinct excited-state absorption species with varied dynamics were identified and assigned to the symmetric (s-) and unsymmetric (u-) Cr(dpa)Cl. The major species is s-Cr(dpa)Cl that undergoes rapid conversion at less than 100 fs from the ligand-centred π-π* state, which is the initially accessed state, to the metal-centred d-d state and then vibrational cooling accompanying the structural relaxation at a time constant ∼2.

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We used transient absorption and time-correlated single photon counting (TCSPC) techniques to investigate the charge transfer reaction in monosilylene-spaced aminostyrene stilbene monomer. With 266 nm excitation, both stilbene (sti) and aminostyrene (ast) moieties were excited. In nonpolar solvents, the transient absorption band centered at 600 nm appeared promptly and is assigned to the excited state of sti*; this state relaxes at time constant 1.

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We studied the excited-state dynamics of trans-4-(N-arylamino)stilbenes with aryl = phenyl (p1H), 4-methoxyphenyl (p1OM), or 4-cyanophenyl (p1CN) in solvents of varied polarity and viscosity by using femtosecond transient absorption and time-correlated single photon counting techniques. In nonpolar solvents the decay is triexponential, in which the rapid component corresponds to vibrational cooling combined with solvation, the intermediate temporal component 41-120 ps to trans-cis isomerization, and the long one ∼1 ns to fluorescence decay of the S state. The S state has a delocalized geometry and charge-transfer characteristics, corresponding to a planar intramolecular charge transfer (PICT) state.

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Article Synopsis
  • A new series of conjugated compounds featuring a -SCH₂- linkage were created from imidazole and coumarin derivatives through chemical methods.
  • Out of twenty synthesized imidazole-coumarin conjugates, three showed promising effectiveness (EC50 values of 5.1-8.4 μM) and a high level of selectivity (>20) against the hepatitis C virus.
  • Structural modifications, like adding a hydrogen atom to the N(1) position of the imidazole and specific substituents on the coumarin, significantly enhanced the compounds' potency and selectivity, offering insights for developing new antiviral agents.
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In this paper, we introduce a general design to construct fluorescence-switching probes by using conjugates of a fluorescent molecular rotor and protein specific ligands for the selective protein detection and real-time tracking of protein degradation in living cells. Upon the interaction of the ligand with the protein ligand-binding domain, the crowded surroundings restrict the bond rotation of the fluorescent molecular rotor to trigger the emission of a strong fluorescence signal, which is reduced upon the addition of a competitive ligand or after protein degradation. With this probe design, two fluorescent probes for MGMT and hCAII proteins were constructed and applied for detecting the endogenous proteins in living cells.

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In this communication, we report a general strategy to create fluorescence switchable probes, where a small molecule ligand is conjugated to a fluorescent molecular rotor, for the selective detection of proteins through a non-enzymatic process. In the presence of target proteins, bond rotation of the molecular rotor is restricted, thereby triggering the emission of strong fluorescence.

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Chikungunya virus (CHIKV) is an arbovirus that was first recognized in an epidemic form in East Africa in 1952-1953. The virus is primarily transmitted through mosquitoes and the resulting disease, chikungunya fever, is found in nearly 40 countries. Neither an effective vaccine nor a specific antiviral drug exists for treatments of chikungunya fever.

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