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R. Renganathan - One of the best experts on this subject based on the ideXlab platform.
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Photosensitization of Colloidal SnO2 Semiconductor Nanoparticles with Xanthene Dyes
Journal of Chemistry, 2013Co-Authors: N. Nagarajan, G. Paramaguru, G. Vanitha, R. RenganathanAbstract:The photochemical behavior of xanthene dyes (fluorescein, erythrosine, and eosin) with colloidal SnO2 nanoparticles was probed by UV-visible, steady state, and time resolved fluorescence measurements. The prepared SnO2 nanoparticles were characterized by using UV-visible and powder XRD measurements. The xanthene dyes were adsorbed on the surface of colloidal SnO2 nanoparticles through electrostatic interaction. Apparent Association Constant () was calculated from the relevant fluorescence data. The larger value of Apparent Association Constant indicates a strong Association between xanthene dyes and SnO2 nanoparticles. The fluorescence quenching is mainly attributed to electron transfer from the excited state xanthenes to the conduction band of colloidal SnO2. The electron transfer mechanism was explained based on the Rehm-Weller equation as well as the energy level diagram.
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Photochemical events during photosensitization of colloidal ZnO nanoparticles by riboflavin
Bulletin of Materials Science, 2012Co-Authors: E Vaishnavi, R. RenganathanAbstract:The photosensitization of colloidal ZnO nanoparticles with riboflavin (RF) was investigated using absorption, fluorescence spectroscopic measurements and time resolved fluorescence measurements. Riboflavin adsorbed strongly on the surface of ZnO nanoparticles. Apparent Association Constant was obtained from the fluorescence quenching measurements. The free energy change, Δ G _et, for electron transfer process has been calculated by applying Rehm Weller equation.
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spectroscopic studies on the interaction of colloidal capped cds nanoparticles with bovine serum albumin
Colloids and Surfaces B: Biointerfaces, 2009Co-Authors: Asha M Jhonsi, Arunkumar Kathiravan, R. RenganathanAbstract:Colloidal uncapped and starch capped CdS (SCdS) nanoparticles were prepared and interaction with bovine serum albumin (BSA) have been studied by UV-visible, FT-IR, steady state, time resolved and synchronous fluorescence spectroscopic measurements. BSA molecules adsorbed on the surface of colloidal CdS through the capping agent. The Apparent Association Constant (K(app)=2.54x10(2) M(-1)) and degree of Association has been calculated (alpha=1.12) from absorption studies. The binding Constant from fluorescence quenching method (6.6x10(2) M(-1)) matches well with that determined from the absorption spectral changes. Static quenching mechanism and conformational changes on BSA molecules were confirmed by time resolved and synchronous fluorescence measurements respectively. The effect of starch capped CdS on the conformation of BSA has been analyzed by means of UV-visible absorption and synchronous fluorescence spectra.
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Photoinduced interaction between xanthene dyes and colloidal CdS nanoparticles
Journal of Molecular Structure, 2009Co-Authors: M. Asha Jhonsi, Arunkumar Kathiravan, R. RenganathanAbstract:Xanthene derivatives namely fluorescein, eosin, erythrosine and rose bengal were examined as sensitizers for colloidal CdS nanoparticles. The interaction of these dyes with colloidal CdS nanoparticles was studied by absorption, infra-red, steady state and time resolved fluorescence spectroscopic measurements. The adsorption of dyes on the surface of colloidal CdS nanoparticles through electrostatic interaction was observed. This adsorption leads to increase in optical density as well as quenching of the emission intensity of dye molecules. The Apparent Association Constant was calculated from fluorescence data. The fluorescence quenching is attributable to electron transfer from excited state dyes to the conduction band of colloidal CdS is established.
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Photoinduced electron transfer from phycoerythrin to colloidal metal semiconductor nanoparticles.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2008Co-Authors: Arunkumar Kathiravan, R. Renganathan, M. Chandramohan, S. SekarAbstract:Abstract Phycoerythrin is a water soluble pigment which absorbs in the visible region at 563 nm. The interaction of phycoerythrin with colloidal metal semiconductors was studied by absorption, FT-IR and fluorescence spectroscopy. Phycoerythrin adsorbed strongly on the surface of TiO2 nanoparticles, the Apparent Association Constant for the Association between colloidal metal-TiO2 nanoparticles and phycoerythrin was determined from fluorescence quenching data. The free energy change (ΔGet) for electron transfer process has been calculated by applying Rehm-Weller equation.
Tadashi Asahi - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the putative α subunit of a heterotrimeric G protein in rice
Plant Molecular Biology, 1997Co-Authors: Yukimoto Iwasaki, Teruhisa Kato, Toshio Kaidoh, Atsushi Ishikawa, Tadashi AsahiAbstract:A recombinant protein with a cDNA that encodes the putative α subunit of a rice heterotrimeric G protein was synthesized in Escherichia coli and purified. The recombinant protein (rGrice α) with an Apparent molecular mass of 45 kDa was bound with guanosine 5′-(3-O-thio)triphosphate with an Apparent Association Constant (kapp) of 0.36. The protein also hydrolyzed GTP and its Kcat was 0.44. rGrice α was ADP-ribosylated by activated cholera toxin. Monoclonal antibodies raised against rGrice α reacted with a 45 kDa polypeptide localized in the plasma membrane of rice seedlings. The peptide map of this polypeptide after digestion with V8 protease was identical to that of rGrice α. A 45 kDa polypeptide in the plasma membrane, as well as rGrice α, was ADP-ribosylated by activated cholera toxin. The GTPase activity of the plasma membrane was stimulated 2.5-fold by mastoparan 7 but not mastoparan 17. These properties were similar to those of the α subunits of heterotrimeric G proteins in animals, suggesting that the putative α subunit is truly the α subunit itself.
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Characterization of the putative alpha subunit of a heterotrimeric G protein in rice.
Plant molecular biology, 1997Co-Authors: Yukimoto Iwasaki, Teruhisa Kato, Toshio Kaidoh, Atsushi Ishikawa, Tadashi AsahiAbstract:A recombinant protein with a cDNA that encodes the putative α subunit of a rice heterotrimeric G protein was synthesized in Escherichia coli and purified. The recombinant protein (rGrice α) with an Apparent molecular mass of 45 kDa was bound with guanosine 5′-(3-O-thio)triphosphate with an Apparent Association Constant (kapp) of 0.36. The protein also hydrolyzed GTP and its Kcat was 0.44. rGrice α was ADP-ribosylated by activated cholera toxin.
Arunkumar Kathiravan - One of the best experts on this subject based on the ideXlab platform.
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Probing electron transfer dynamics of pyranine with reduced graphene oxide
Physical chemistry chemical physics : PCCP, 2014Co-Authors: M. Asha Jhonsi, C. Nithya, Arunkumar KathiravanAbstract:A stable reduced graphene oxide (rGO) was prepared and characterized by X-ray diffraction (XRD) and laser Raman spectroscopy. Steady state and time-resolved fluorescence quenching studies have been carried out to elucidate the process of electron transfer from excited pyranine (POH) into the rGO dispersion. POH adsorbed strongly on rGO dispersion with an Apparent Association Constant of 33.4 (mg ml)−1, and its fluorescence emission was quenched with an Apparent Association Constant of 33.7 (mg ml)−1. Picosecond lifetime measurements gave the rate Constant for the electron transfer process from the excited singlet state of POH into the rGO dispersion as 8.8 × 109 s−1. Laser flash photolysis studies demonstrated the formation of radicals for the evidence of electron transfer between POH and rGO.
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spectroscopic studies on the interaction of colloidal capped cds nanoparticles with bovine serum albumin
Colloids and Surfaces B: Biointerfaces, 2009Co-Authors: Asha M Jhonsi, Arunkumar Kathiravan, R. RenganathanAbstract:Colloidal uncapped and starch capped CdS (SCdS) nanoparticles were prepared and interaction with bovine serum albumin (BSA) have been studied by UV-visible, FT-IR, steady state, time resolved and synchronous fluorescence spectroscopic measurements. BSA molecules adsorbed on the surface of colloidal CdS through the capping agent. The Apparent Association Constant (K(app)=2.54x10(2) M(-1)) and degree of Association has been calculated (alpha=1.12) from absorption studies. The binding Constant from fluorescence quenching method (6.6x10(2) M(-1)) matches well with that determined from the absorption spectral changes. Static quenching mechanism and conformational changes on BSA molecules were confirmed by time resolved and synchronous fluorescence measurements respectively. The effect of starch capped CdS on the conformation of BSA has been analyzed by means of UV-visible absorption and synchronous fluorescence spectra.
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Photoinduced interaction between xanthene dyes and colloidal CdS nanoparticles
Journal of Molecular Structure, 2009Co-Authors: M. Asha Jhonsi, Arunkumar Kathiravan, R. RenganathanAbstract:Xanthene derivatives namely fluorescein, eosin, erythrosine and rose bengal were examined as sensitizers for colloidal CdS nanoparticles. The interaction of these dyes with colloidal CdS nanoparticles was studied by absorption, infra-red, steady state and time resolved fluorescence spectroscopic measurements. The adsorption of dyes on the surface of colloidal CdS nanoparticles through electrostatic interaction was observed. This adsorption leads to increase in optical density as well as quenching of the emission intensity of dye molecules. The Apparent Association Constant was calculated from fluorescence data. The fluorescence quenching is attributable to electron transfer from excited state dyes to the conduction band of colloidal CdS is established.
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Photoinduced electron transfer from phycoerythrin to colloidal metal semiconductor nanoparticles.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2008Co-Authors: Arunkumar Kathiravan, R. Renganathan, M. Chandramohan, S. SekarAbstract:Abstract Phycoerythrin is a water soluble pigment which absorbs in the visible region at 563 nm. The interaction of phycoerythrin with colloidal metal semiconductors was studied by absorption, FT-IR and fluorescence spectroscopy. Phycoerythrin adsorbed strongly on the surface of TiO2 nanoparticles, the Apparent Association Constant for the Association between colloidal metal-TiO2 nanoparticles and phycoerythrin was determined from fluorescence quenching data. The free energy change (ΔGet) for electron transfer process has been calculated by applying Rehm-Weller equation.
Yukimoto Iwasaki - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the putative α subunit of a heterotrimeric G protein in rice
Plant Molecular Biology, 1997Co-Authors: Yukimoto Iwasaki, Teruhisa Kato, Toshio Kaidoh, Atsushi Ishikawa, Tadashi AsahiAbstract:A recombinant protein with a cDNA that encodes the putative α subunit of a rice heterotrimeric G protein was synthesized in Escherichia coli and purified. The recombinant protein (rGrice α) with an Apparent molecular mass of 45 kDa was bound with guanosine 5′-(3-O-thio)triphosphate with an Apparent Association Constant (kapp) of 0.36. The protein also hydrolyzed GTP and its Kcat was 0.44. rGrice α was ADP-ribosylated by activated cholera toxin. Monoclonal antibodies raised against rGrice α reacted with a 45 kDa polypeptide localized in the plasma membrane of rice seedlings. The peptide map of this polypeptide after digestion with V8 protease was identical to that of rGrice α. A 45 kDa polypeptide in the plasma membrane, as well as rGrice α, was ADP-ribosylated by activated cholera toxin. The GTPase activity of the plasma membrane was stimulated 2.5-fold by mastoparan 7 but not mastoparan 17. These properties were similar to those of the α subunits of heterotrimeric G proteins in animals, suggesting that the putative α subunit is truly the α subunit itself.
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Characterization of the putative alpha subunit of a heterotrimeric G protein in rice.
Plant molecular biology, 1997Co-Authors: Yukimoto Iwasaki, Teruhisa Kato, Toshio Kaidoh, Atsushi Ishikawa, Tadashi AsahiAbstract:A recombinant protein with a cDNA that encodes the putative α subunit of a rice heterotrimeric G protein was synthesized in Escherichia coli and purified. The recombinant protein (rGrice α) with an Apparent molecular mass of 45 kDa was bound with guanosine 5′-(3-O-thio)triphosphate with an Apparent Association Constant (kapp) of 0.36. The protein also hydrolyzed GTP and its Kcat was 0.44. rGrice α was ADP-ribosylated by activated cholera toxin.
Wojciech Bal - One of the best experts on this subject based on the ideXlab platform.
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Stochastic or Not? Method To Predict and Quantify the Stochastic Effects on the Association Reaction Equilibria in Nanoscopic Systems.
The journal of physical chemistry. A, 2020Co-Authors: Wojciech Goch, Wojciech BalAbstract:The stochastic nature of chemical reaction and impact of the stochasticity on their evolution is soundly documented. Both theoretical predictions and emerging experimental evidence indicate the influence of stochastic effects on the equilibrium state of Association reaction. In this work simple mathematical formulas are introduced to estimate these effects. First, the dependence of the ratio of observed reactants (Apparent Association Constant, equivalent of macroscopic Association Constant in stochastic analysis) on the volume and the number of molecules of reagents is discussed and the limiting factors of this effect are shown. Next, the Apparent Association Constant is approximated for nanoscale systems by closed-form formulas derived for this purpose. Finally, an estimation for the macroscopic Constant value from the Apparent one is provided and validated on the published experimental data. This work was inspired by chemical reactions occurring in biological compartments, but the results can be used for all systems belonging to the stochastic regime of chemical reactions.
