Jeong-Hyon Ha - Academia.edu (original) (raw)
Papers by Jeong-Hyon Ha
Chemical Physics Letters, Feb 1, 2021
Background: A major hurdle in the use of exogenous stems cells for therapeutic regeneration of in... more Background: A major hurdle in the use of exogenous stems cells for therapeutic regeneration of injured myocardium remains the poor survival of implanted cells. To date, the delivery of stem cells into myocardium has largely focused on implantation of cell suspensions. Methodology and Principal Findings: We hypothesize that delivering progenitor cells in an aggregate form would serve to mimic the endogenous state with proper cell-cell contact, and may aid the survival of implanted cells. Microwell methodologies allow for the culture of homogenous 3D cell aggregates, thereby allowing cell-cell contact. In this study, we find that the culture of cardiac progenitor cells in a 3D cell aggregate augments cell survival and protects against cellular toxins and stressors, including hydrogen peroxide and anoxia/reoxygenation induced cell death. Moreover, using a murine model of cardiac ischemia-reperfusion injury, we find that delivery of cardiac progenitor cells in the form of 3D aggregates improved in vivo survival of implanted cells. Conclusion: Collectively, our data support the notion that growth in 3D cellular systems and maintenance of cell-cell contact improves exogenous cell survival following delivery into myocardium. These approaches may serve as a strategy to improve cardiovascular cell-based therapies.
Journal of Analytical Science and Technology, Sep 30, 2011
ABSTRACT Luminescence lifetimes of anion complexes of manganese (III) porphyrins incorporated in ... more ABSTRACT Luminescence lifetimes of anion complexes of manganese (III) porphyrins incorporated in the PVC polymer film were investigated by the time-correlated single photon counting (TCSPC) method. The tripquintet state lifetimes (tens of picoseconds) which had ...
Photothermal properties depend on the characteristics of energy transfer processes in solution. I... more Photothermal properties depend on the characteristics of energy transfer processes in solution. In this study, a time-resolved single beam thermal lens experiment in various solvents is employed to investigate the energy coupling effects which govern the energy transfer processes. Interestingly, it is observed that the behaviour of the photothermal propagation in solution depends on the property of solution and the concentration of solute in a single beam thermal lens configuration. These characteristics lead us to consider the solute-solvent coupling effects as well as the solvent-solvent interactions.
Rapid Communication in Photoscience
The Journal of Chemical Physics, 2006
The Journal of Chemical Physics, 2006
Journal of Analytical Science, Jan 1, 2011
ABSTRACT Luminescence lifetimes of anion complexes of manganese (III) porphyrins incorporated in ... more ABSTRACT Luminescence lifetimes of anion complexes of manganese (III) porphyrins incorporated in the PVC polymer film were investigated by the time-correlated single photon counting (TCSPC) method. The tripquintet state lifetimes (tens of picoseconds) which had ...
Chemical Physics, Jan 1, 2011
Journal of Analytical Science, Jan 1, 2011
ABSTRACT We measured thermally originated solid phase nonlinear optical properties of manganese p... more ABSTRACT We measured thermally originated solid phase nonlinear optical properties of manganese porphyrin-incorporated PVC polymer film using CW low-power Z-scan and optical power limiting methods. The nonlinear refractive index (n 2) of this porphyrin film is ...
Chemical Physics Letters, Jan 1, 2011
The effects of aqueous environments on the perchlorate infrared lineshape were investigated in va... more The effects of aqueous environments on the perchlorate infrared lineshape were investigated in various ionic solutions, including a polymeric polyvinyl chloride membrane and perchlorate coordinated to manganese(III) porphyrin, using the model frequency-frequency correlation function (FFCF). The perchlorate ligand moiety is considered a useful infrared probe in aqueous nanoscopic environments. We observed an asymmetric mode of the ligated perchlorate, in which the lineshape had a smaller bandwidth and faster dynamics than that of a 1 M perchlorate aqueous solution. In the 6 M solutions, we observed at least two conformations with faster dynamics than that of the 1 M solution, regardless of whether it was in the heterogeneous polymer matrix.
The Journal of …, Jan 1, 2010
Aromatic compounds with electron-donating or -accepting substituents exhibit interesting resonanc... more Aromatic compounds with electron-donating or -accepting substituents exhibit interesting resonance effects on a variety of chemical reactivities and optical properties. To understand such effects and the possible relationship between vibrational energy dissipation pathways and resonance structures of aromatic compounds, we studied ortho-, meta-, and para-substituted cyanophenols and their anionic forms in methanol by using time-and frequency-resolved pump-probe and two-dimensional IR spectroscopy, where the nitrile group acts as an IR probe. From the measured transient spectra and singular-value decomposition analyses, we found that there is a combination band whose frequency is very close to that of the nitrile stretch mode. Due to the difference in the lifetimes of these two mode excited states, the transient pump-probe spectra commonly show notable blue-shifting behaviors in time. Comparing the vibrational lifetimes of neutral cyanophenols and cyanophenoxide anions in methanol and carrying out quantum mechanical/molecular mechanical molecular dynamics simulations to study hydrogen-bonding dynamics, we found that the vibrational energy of the nitrile stretch mode initially relaxes to intramolecular degrees of freedom instead of solvent modes. Also, the vibrational anharmonic frequency shifts, intrinsic lifetimes, and bandwidths of the nitrile stretch mode and the combination mode in these molecular systems are fully characterized, and their relationships with resonance structures are discussed. It is believed that the present work sheds light on the intrinsic vibrational relaxation process of the nitrile stretch mode in cyanophenols, even in the case when their IR spectra are congested by the spectrally overlapping combination bands, and the resonance effects of aromatic compounds on vibrational dynamics and relaxation processes.
BULLETIN-KOREAN …, Jan 1, 2002
The Journal of chemical physics, Jan 1, 2009
By means of integrated and dispersed IR photon echo measurement methods, the vibrational dynamics... more By means of integrated and dispersed IR photon echo measurement methods, the vibrational dynamics of C-N stretch modes in 4-cyanophenol and 4-cyanophenoxide in methanol is investigated. The vibrational frequency-frequency correlation function ͑FFCF͒ is retrieved from the integrated photon echo signals by assuming that the FFCF is described by two exponential functions with about 400 fs and a few picosecond components. The excited state lifetimes of the C-N stretch modes of neutral and anionic 4-cyanophenols are 1.45 and 0.91 ps, respectively, and the overtone anharmonic frequency shifts are 25 and 28 cm −1 . At short waiting times, a notable underdamped oscillation, which is attributed to a low-frequency intramolecular vibration coupled to the CN stretch, in the integrated and dispersed vibrational echo as well as transient grating signals was observed. The spectral bandwidths of IR absorption and dispersed vibrational echo spectra of the 4-cyanophenoxide are significantly larger than those of its neutral form, indicating that the strong interaction between phenoxide and methanol causes large frequency fluctuation and rapid population relaxation. The resonance effects in a paradisubstituted aromatic compound would be of interest in understanding the conjugation effects and their influences on chemical reactivity of various aromatic compounds in organic solvents.
Journal of molecular structure, Jan 1, 2002
Photophysical properties of tetraphenylporphyrin (H 2 TPP), tetra(p-hydroxyphenyl)porphyrin ((p-O... more Photophysical properties of tetraphenylporphyrin (H 2 TPP), tetra(p-hydroxyphenyl)porphyrin ((p-OH) 4 TPPH 2 ), germanium(IV) tetraphenylporphyrin dichloride (GeTPPCl 2 ), and germanium(IV) tetra(p-hydroxyphenyl)porphyrin dichloride (Ge(p-OH) 4 TPPCl 2 ) have been investigated to elucidate the effects of para OH substituents on the free-base and the metalincorporated porphyrin p systems by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were correlated with various molecular aspects, such as extended p-conjugation, nonplanar structural distortion, and central heavy atoms. Changes to steady-state absorption and¯uorescence spectral characteristics of the OH-substituted porphyrin derivatives were attributed to the enhanced p-conjugation between phenyl ring and porphyrin p-electron system in the ground and the excited states. Such p-conjugation effects of the OH-substituted derivatives are greater when Ge(IV) is introduced into the core. The enhanced p-electron interaction of the OH-substituted derivatives in the excited state shortened the¯uorescence lifetimes but increased the¯uorescence quantum yields since the radiative rate was enhanced more than thē uorescence decay rate increased. The radiative decay rate of the OH-substituted Ge(IV) porphyrin is even greater due to more intensive p-conjugation of the metalloporphyrin in the excited state. The metal incorporation into the core also enhanced the nonradiative decay rates due to increased spin±orbit coupling and, consequently, reduced the¯uorescence lifetimes and quantum yields. However, the spin±orbit coupling effect is not as large as expected. On the other hand, the OH group substitution enhanced only the nonradiative decay rate of the Ge(IV) metalloporphyrin and did not increase that of the free base porphyrin. This is ascribed to much more intensive p-conjugation of the Ge(IV) metalloporphyrin in the excited state which may induce excited state charge transfer and structural distortion. q
BULLETIN-KOREAN …, Jan 1, 2001
The photophysical properties and the singlet oxygen generation efficiency of tetrathiarubyrin hav... more The photophysical properties and the singlet oxygen generation efficiency of tetrathiarubyrin have been investigated to elucidate the possibility of its use as a photodynamic therapy (PDT) photosensitizer by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were affected by various molecular aspects, such as extended π conjugation, structural distortion, and internal heavy atom. The steady-state electronic absorption spectrum was red-shifted due to the extended π -conjugation, and the spin orbital coupling was enhanced by the structural distortion and the internal heavy atom effect. As a result of the enhanced spin orbital coupling, the triplet quantum yield increased to 0.90 ± 0.10 and the triplet state lifetime was shortened to 7.0 ± 1.2 µs. Since the triplet state decays at a relatively faster rate, the efficiency of the oxygen quenching of the triplet state decreases. The singlet oxygen quantum yield was estimated to be 0.52 ± 0.02, which is somewhat lower than expected. On the other hand, the efficiency of singlet oxygen generation during the oxygen quenching of triplet state, f ∆ T , is near unity. Such high efficiency of singlet oxygen generation can be explained by the following two possible factors: The hydrogen bonding of ethanol which impedes the deactivation pathway of the charge transfer complex with oxygen to the ground state, the less probability of the aggregation formation.
…, Jan 1, 2003
Femtosecond time-resolved transient absorption studies have been performed to investigate the pho... more Femtosecond time-resolved transient absorption studies have been performed to investigate the photoinduced energy and electrontransfer processes in Zn(II)porphyrin ± Zn(II)chlorin ± fullerene triad in which energy and oxidation potential gradients are directed along the donor ± acceptor-linked arrays. Fast energy transfer (% 450 fs) from photoexcited Zn(II)porphyrin to Zn(II)chlorin was observed upon selective photoexcitation of Zn(II)porphyrin unit in the triad. In a nonpolar solvent such as toluene, the energy transfer from the excited singlet state of Zn(II)chlorin to fullerene occurs and is followed by the formation of an intermediate state with a time constant of nanoseconds, which was attributed to the intramolecular exciplex between Zn(II)chlorin and fullerene. In benzonitrile, on the other hand, the photoexcitation of the triad results in the fast electron transfer (< 1 ps) from photoexcited Zn(II)chlorin to fullerene. The generated charge-separated species recombine with a time constant of % 12 ps. The relatively fast charge separation and charge recombination rates imply that the strong electronic coupling between Zn(II)chlorin and fullerene moieties is probably induced by the folded conformation between Zn(II)chlorin and fullerene moieties which enhances direct through-space interaction between the proximately contacted p systems.
The Journal of …, Jan 1, 2003
... Hyun Sun Cho, Jae Kyu Song, Jeong-Hyon Ha, Sung Cho, and Dongho Kim* . Center for Ultrafast ... more ... Hyun Sun Cho, Jae Kyu Song, Jeong-Hyon Ha, Sung Cho, and Dongho Kim* . Center for Ultrafast Optical Characteristics Control and Department of Chemistry, Yonsei University, Seoul 120-749, Korea. Naoya Yoshida and Atsuhiro Osuka*. ...
Chemical Physics Letters, Feb 1, 2021
Background: A major hurdle in the use of exogenous stems cells for therapeutic regeneration of in... more Background: A major hurdle in the use of exogenous stems cells for therapeutic regeneration of injured myocardium remains the poor survival of implanted cells. To date, the delivery of stem cells into myocardium has largely focused on implantation of cell suspensions. Methodology and Principal Findings: We hypothesize that delivering progenitor cells in an aggregate form would serve to mimic the endogenous state with proper cell-cell contact, and may aid the survival of implanted cells. Microwell methodologies allow for the culture of homogenous 3D cell aggregates, thereby allowing cell-cell contact. In this study, we find that the culture of cardiac progenitor cells in a 3D cell aggregate augments cell survival and protects against cellular toxins and stressors, including hydrogen peroxide and anoxia/reoxygenation induced cell death. Moreover, using a murine model of cardiac ischemia-reperfusion injury, we find that delivery of cardiac progenitor cells in the form of 3D aggregates improved in vivo survival of implanted cells. Conclusion: Collectively, our data support the notion that growth in 3D cellular systems and maintenance of cell-cell contact improves exogenous cell survival following delivery into myocardium. These approaches may serve as a strategy to improve cardiovascular cell-based therapies.
Journal of Analytical Science and Technology, Sep 30, 2011
ABSTRACT Luminescence lifetimes of anion complexes of manganese (III) porphyrins incorporated in ... more ABSTRACT Luminescence lifetimes of anion complexes of manganese (III) porphyrins incorporated in the PVC polymer film were investigated by the time-correlated single photon counting (TCSPC) method. The tripquintet state lifetimes (tens of picoseconds) which had ...
Photothermal properties depend on the characteristics of energy transfer processes in solution. I... more Photothermal properties depend on the characteristics of energy transfer processes in solution. In this study, a time-resolved single beam thermal lens experiment in various solvents is employed to investigate the energy coupling effects which govern the energy transfer processes. Interestingly, it is observed that the behaviour of the photothermal propagation in solution depends on the property of solution and the concentration of solute in a single beam thermal lens configuration. These characteristics lead us to consider the solute-solvent coupling effects as well as the solvent-solvent interactions.
Rapid Communication in Photoscience
The Journal of Chemical Physics, 2006
The Journal of Chemical Physics, 2006
Journal of Analytical Science, Jan 1, 2011
ABSTRACT Luminescence lifetimes of anion complexes of manganese (III) porphyrins incorporated in ... more ABSTRACT Luminescence lifetimes of anion complexes of manganese (III) porphyrins incorporated in the PVC polymer film were investigated by the time-correlated single photon counting (TCSPC) method. The tripquintet state lifetimes (tens of picoseconds) which had ...
Chemical Physics, Jan 1, 2011
Journal of Analytical Science, Jan 1, 2011
ABSTRACT We measured thermally originated solid phase nonlinear optical properties of manganese p... more ABSTRACT We measured thermally originated solid phase nonlinear optical properties of manganese porphyrin-incorporated PVC polymer film using CW low-power Z-scan and optical power limiting methods. The nonlinear refractive index (n 2) of this porphyrin film is ...
Chemical Physics Letters, Jan 1, 2011
The effects of aqueous environments on the perchlorate infrared lineshape were investigated in va... more The effects of aqueous environments on the perchlorate infrared lineshape were investigated in various ionic solutions, including a polymeric polyvinyl chloride membrane and perchlorate coordinated to manganese(III) porphyrin, using the model frequency-frequency correlation function (FFCF). The perchlorate ligand moiety is considered a useful infrared probe in aqueous nanoscopic environments. We observed an asymmetric mode of the ligated perchlorate, in which the lineshape had a smaller bandwidth and faster dynamics than that of a 1 M perchlorate aqueous solution. In the 6 M solutions, we observed at least two conformations with faster dynamics than that of the 1 M solution, regardless of whether it was in the heterogeneous polymer matrix.
The Journal of …, Jan 1, 2010
Aromatic compounds with electron-donating or -accepting substituents exhibit interesting resonanc... more Aromatic compounds with electron-donating or -accepting substituents exhibit interesting resonance effects on a variety of chemical reactivities and optical properties. To understand such effects and the possible relationship between vibrational energy dissipation pathways and resonance structures of aromatic compounds, we studied ortho-, meta-, and para-substituted cyanophenols and their anionic forms in methanol by using time-and frequency-resolved pump-probe and two-dimensional IR spectroscopy, where the nitrile group acts as an IR probe. From the measured transient spectra and singular-value decomposition analyses, we found that there is a combination band whose frequency is very close to that of the nitrile stretch mode. Due to the difference in the lifetimes of these two mode excited states, the transient pump-probe spectra commonly show notable blue-shifting behaviors in time. Comparing the vibrational lifetimes of neutral cyanophenols and cyanophenoxide anions in methanol and carrying out quantum mechanical/molecular mechanical molecular dynamics simulations to study hydrogen-bonding dynamics, we found that the vibrational energy of the nitrile stretch mode initially relaxes to intramolecular degrees of freedom instead of solvent modes. Also, the vibrational anharmonic frequency shifts, intrinsic lifetimes, and bandwidths of the nitrile stretch mode and the combination mode in these molecular systems are fully characterized, and their relationships with resonance structures are discussed. It is believed that the present work sheds light on the intrinsic vibrational relaxation process of the nitrile stretch mode in cyanophenols, even in the case when their IR spectra are congested by the spectrally overlapping combination bands, and the resonance effects of aromatic compounds on vibrational dynamics and relaxation processes.
BULLETIN-KOREAN …, Jan 1, 2002
The Journal of chemical physics, Jan 1, 2009
By means of integrated and dispersed IR photon echo measurement methods, the vibrational dynamics... more By means of integrated and dispersed IR photon echo measurement methods, the vibrational dynamics of C-N stretch modes in 4-cyanophenol and 4-cyanophenoxide in methanol is investigated. The vibrational frequency-frequency correlation function ͑FFCF͒ is retrieved from the integrated photon echo signals by assuming that the FFCF is described by two exponential functions with about 400 fs and a few picosecond components. The excited state lifetimes of the C-N stretch modes of neutral and anionic 4-cyanophenols are 1.45 and 0.91 ps, respectively, and the overtone anharmonic frequency shifts are 25 and 28 cm −1 . At short waiting times, a notable underdamped oscillation, which is attributed to a low-frequency intramolecular vibration coupled to the CN stretch, in the integrated and dispersed vibrational echo as well as transient grating signals was observed. The spectral bandwidths of IR absorption and dispersed vibrational echo spectra of the 4-cyanophenoxide are significantly larger than those of its neutral form, indicating that the strong interaction between phenoxide and methanol causes large frequency fluctuation and rapid population relaxation. The resonance effects in a paradisubstituted aromatic compound would be of interest in understanding the conjugation effects and their influences on chemical reactivity of various aromatic compounds in organic solvents.
Journal of molecular structure, Jan 1, 2002
Photophysical properties of tetraphenylporphyrin (H 2 TPP), tetra(p-hydroxyphenyl)porphyrin ((p-O... more Photophysical properties of tetraphenylporphyrin (H 2 TPP), tetra(p-hydroxyphenyl)porphyrin ((p-OH) 4 TPPH 2 ), germanium(IV) tetraphenylporphyrin dichloride (GeTPPCl 2 ), and germanium(IV) tetra(p-hydroxyphenyl)porphyrin dichloride (Ge(p-OH) 4 TPPCl 2 ) have been investigated to elucidate the effects of para OH substituents on the free-base and the metalincorporated porphyrin p systems by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were correlated with various molecular aspects, such as extended p-conjugation, nonplanar structural distortion, and central heavy atoms. Changes to steady-state absorption and¯uorescence spectral characteristics of the OH-substituted porphyrin derivatives were attributed to the enhanced p-conjugation between phenyl ring and porphyrin p-electron system in the ground and the excited states. Such p-conjugation effects of the OH-substituted derivatives are greater when Ge(IV) is introduced into the core. The enhanced p-electron interaction of the OH-substituted derivatives in the excited state shortened the¯uorescence lifetimes but increased the¯uorescence quantum yields since the radiative rate was enhanced more than thē uorescence decay rate increased. The radiative decay rate of the OH-substituted Ge(IV) porphyrin is even greater due to more intensive p-conjugation of the metalloporphyrin in the excited state. The metal incorporation into the core also enhanced the nonradiative decay rates due to increased spin±orbit coupling and, consequently, reduced the¯uorescence lifetimes and quantum yields. However, the spin±orbit coupling effect is not as large as expected. On the other hand, the OH group substitution enhanced only the nonradiative decay rate of the Ge(IV) metalloporphyrin and did not increase that of the free base porphyrin. This is ascribed to much more intensive p-conjugation of the Ge(IV) metalloporphyrin in the excited state which may induce excited state charge transfer and structural distortion. q
BULLETIN-KOREAN …, Jan 1, 2001
The photophysical properties and the singlet oxygen generation efficiency of tetrathiarubyrin hav... more The photophysical properties and the singlet oxygen generation efficiency of tetrathiarubyrin have been investigated to elucidate the possibility of its use as a photodynamic therapy (PDT) photosensitizer by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were affected by various molecular aspects, such as extended π conjugation, structural distortion, and internal heavy atom. The steady-state electronic absorption spectrum was red-shifted due to the extended π -conjugation, and the spin orbital coupling was enhanced by the structural distortion and the internal heavy atom effect. As a result of the enhanced spin orbital coupling, the triplet quantum yield increased to 0.90 ± 0.10 and the triplet state lifetime was shortened to 7.0 ± 1.2 µs. Since the triplet state decays at a relatively faster rate, the efficiency of the oxygen quenching of the triplet state decreases. The singlet oxygen quantum yield was estimated to be 0.52 ± 0.02, which is somewhat lower than expected. On the other hand, the efficiency of singlet oxygen generation during the oxygen quenching of triplet state, f ∆ T , is near unity. Such high efficiency of singlet oxygen generation can be explained by the following two possible factors: The hydrogen bonding of ethanol which impedes the deactivation pathway of the charge transfer complex with oxygen to the ground state, the less probability of the aggregation formation.
…, Jan 1, 2003
Femtosecond time-resolved transient absorption studies have been performed to investigate the pho... more Femtosecond time-resolved transient absorption studies have been performed to investigate the photoinduced energy and electrontransfer processes in Zn(II)porphyrin ± Zn(II)chlorin ± fullerene triad in which energy and oxidation potential gradients are directed along the donor ± acceptor-linked arrays. Fast energy transfer (% 450 fs) from photoexcited Zn(II)porphyrin to Zn(II)chlorin was observed upon selective photoexcitation of Zn(II)porphyrin unit in the triad. In a nonpolar solvent such as toluene, the energy transfer from the excited singlet state of Zn(II)chlorin to fullerene occurs and is followed by the formation of an intermediate state with a time constant of nanoseconds, which was attributed to the intramolecular exciplex between Zn(II)chlorin and fullerene. In benzonitrile, on the other hand, the photoexcitation of the triad results in the fast electron transfer (< 1 ps) from photoexcited Zn(II)chlorin to fullerene. The generated charge-separated species recombine with a time constant of % 12 ps. The relatively fast charge separation and charge recombination rates imply that the strong electronic coupling between Zn(II)chlorin and fullerene moieties is probably induced by the folded conformation between Zn(II)chlorin and fullerene moieties which enhances direct through-space interaction between the proximately contacted p systems.
The Journal of …, Jan 1, 2003
... Hyun Sun Cho, Jae Kyu Song, Jeong-Hyon Ha, Sung Cho, and Dongho Kim* . Center for Ultrafast ... more ... Hyun Sun Cho, Jae Kyu Song, Jeong-Hyon Ha, Sung Cho, and Dongho Kim* . Center for Ultrafast Optical Characteristics Control and Department of Chemistry, Yonsei University, Seoul 120-749, Korea. Naoya Yoshida and Atsuhiro Osuka*. ...