Browsing by Author "Wu, Chia-Yan"

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Photodissociation dynamics of fluorobenzene (C6H5F) at 157 and 193 nm: Branching ratios and distributions of kinetic energy
(2006-10-14)
Lee, Shih-Huang
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Wu, Chia-Yan
;
Yang, Sheng-Kai
;
Lee, Yuan-Pern
;
應用化學系
Following photodissociation of fluorobenzene (C6H5F) at 193 and 157 nm, we detected the products with fragmentation-translational spectroscopy by utilizing a tunable vacuum ultraviolet beam from a synchrotron for ionization. Between two primary dissociation channels observed upon irradiation at 193 (157) nm, the HF-elimination channel C6H5F -> HF+C6H4 dominates, with a branching ratio of 0.94 +/- 0.02 (0.61 +/- 0.05) and an average release of kinetic energy of 103 (108) kJ mol(-1); the H-elimination channel C6H5F -> H+C6H4F has a branching ratio of 0.06 +/- 0.02 (0.39 +/- 0.05) and an average release of kinetic energy of 18.6 (26.8) kJ mol(-1). Photofragments H, HF, C6H4, and C6H4F produced via the one-photon process have nearly isotropic angular distributions. Both the HF-elimination and the H-elimination channels likely proceed via the ground-state electronic surface following internal conversion of C6H5F; these channels exhibit small fractions of kinetic energy release from the available energy, indicating that the molecular fragments are highly internally excited. We also determined the ionization energy of C6H4F to be 8.6 +/- 0.2 eV. (c) 2006 American Institute of Physics.
Probing the binding kinetics of proinflammatory cytokine-antibody interactions using dual color fluorescence cross correlation spectroscopy
(2011)
Wu, Chia-Yan
;
Huang, Chuan-Keng
;
Chung, Chao-Yu
;
Huang, I-Ping
;
Hwu, Yeukuang
Dual color fluorescence cross correlation spectroscopy (FCCS) was used to investigate quantitatively the binding kinetics of tumor necrosis factor (TNF alpha) with TNF alpha antibody (anti-TNF alpha) following fluorescent labeling. Through the analysis of the auto correlation curves of fluorescence correlation spectroscopy (FCS), diffusion coefficients of 100.06 +/- 4.9 mu m(2) s(-1) and 48.96 +/- 2.52 mu m(2) s(-1) for Alexa488-TNF alpha and Atto647N-anti-TNF alpha were obtained. In addition, the calculated hydrodynamic diameters of the Alexa488-TNF alpha and Atto647N-anti-TNF alpha were approximately 4.89 +/- 0.24 nm and 9.99 +/- 0.52 nm, respectively, which agrees with the values of 5.20 +/- 1.23 nm and 9.28 +/- 0.86 nm for the native TNF alpha and the anti-TNF alpha as determined from dynamic light scattering measurements. For the binding kinetics, association (k(on)) and dissociation (k(off)) rate constants were (1.13 +/- 0.08) x 10(4) M(-1) s(-1) and (1.53 +/- 0.19) x 10(-3) s(-1) while the corresponding dissociation constant (K(d)) at 25 degrees C was (1.36 +/- 0.10) x 10(-7) M. We believe this is the first report on the binding kinetics for TNF alpha-antibody recognition in the homogeneous phase. Using this technology, we have shown that controlled experiments can be performed to gain insight into molecular mechanisms involved in the immune response.