“…Additionally, if enzyme adsorbs on bare quartz, then a condition similar to that of Iwado et al with silanol groups cocatalyzing NADH reduction and H 2 O 2 formation may pertain. 44 Furthermore, Olson's observation that MB initially decreased the rate of oxygen consumption is consistent with the known adsorption of MB on quartz, passivating silanol groups. 14,48 In the case of Figure 3, four 2 cm × 0.75 cm quartz slides as described in the Experimental Section and shown in Figure 1 were inserted into the reactor, with one slide withdrawn for SEM imaging after each experiment, with the last slide allowed to age an additional 2 days in distilled water before microscopy.…”
Section: Resultssupporting
confidence: 66%
“…In fact, because the biofilm appears to passivate the reactor, a dirty, biofilm-covered reactor may result in fewer measurement artifacts than a clean surface. Additionally, if enzyme adsorbs on bare quartz, then a condition similar to that of Iwado et al with silanol groups cocatalyzing NADH reduction and H 2 O 2 formation may pertain . Furthermore, Olson's observation that MB initially decreased the rate of oxygen consumption is consistent with the known adsorption of MB on quartz, passivating silanol groups. , 2 Three consecutive runs.…”
Section: Resultsmentioning
confidence: 65%
“…(b) No surface catalysis rate constants for the hypothesized reactions were measured, nor are they available to our knowledge in the literature. (The closest work being with nicotinamde and protein but not oxygen radical systems. − ) (c) To emphasize the qualitative nature of the present model, we chose not to use the BFSO model, generally believed (including by us) to be superior to the Urbanalator. (d) The chemistry of 2,4-DCP and MB does not explicitly appear.…”
Section: Simulationmentioning
confidence: 99%
“…We did not publish at that time, as the model had arbitrary rate parameters and no experimental verification. SciFinder searches for other citations of the effect of the reactor surface on oscillatory peroxidase kinetics proved fruitless, although porphines adsorbed on silica catalyze NADH reduction better than the same unsupported catalysts. , The rate of HRP adsorption on glass at pH 6 is similar to the rate at which Olson's oscillatory reactions damped but fails to explain Lvovich's result that adding silica surface area to the PO reaction actually accelerates oxygen consumption . It has long been known that one of the cofactors in the PO reaction, methylene blue (MB), adsorbs on quartz .…”
In experiments on the kinetics of the peroxidase-oxidase oscillatory reaction in pH 5.l acetate buffer, biofilms form in less than 48 h on the quartz reactor surface. The nominally homogeneous peroxidase system shows dynamical changes in response to this biofilm growth, partially explaining subtle differences among dynamics observed over time and between laboratories. Kinetics data and model computations are correlated with micrographs of biofilm formation. It is evident that bare quartz also interacts with reaction species, so that the surface area-to-volume ratio is an important parameter on which observed dynamics depend.
“…Additionally, if enzyme adsorbs on bare quartz, then a condition similar to that of Iwado et al with silanol groups cocatalyzing NADH reduction and H 2 O 2 formation may pertain. 44 Furthermore, Olson's observation that MB initially decreased the rate of oxygen consumption is consistent with the known adsorption of MB on quartz, passivating silanol groups. 14,48 In the case of Figure 3, four 2 cm × 0.75 cm quartz slides as described in the Experimental Section and shown in Figure 1 were inserted into the reactor, with one slide withdrawn for SEM imaging after each experiment, with the last slide allowed to age an additional 2 days in distilled water before microscopy.…”
Section: Resultssupporting
confidence: 66%
“…In fact, because the biofilm appears to passivate the reactor, a dirty, biofilm-covered reactor may result in fewer measurement artifacts than a clean surface. Additionally, if enzyme adsorbs on bare quartz, then a condition similar to that of Iwado et al with silanol groups cocatalyzing NADH reduction and H 2 O 2 formation may pertain . Furthermore, Olson's observation that MB initially decreased the rate of oxygen consumption is consistent with the known adsorption of MB on quartz, passivating silanol groups. , 2 Three consecutive runs.…”
Section: Resultsmentioning
confidence: 65%
“…(b) No surface catalysis rate constants for the hypothesized reactions were measured, nor are they available to our knowledge in the literature. (The closest work being with nicotinamde and protein but not oxygen radical systems. − ) (c) To emphasize the qualitative nature of the present model, we chose not to use the BFSO model, generally believed (including by us) to be superior to the Urbanalator. (d) The chemistry of 2,4-DCP and MB does not explicitly appear.…”
Section: Simulationmentioning
confidence: 99%
“…We did not publish at that time, as the model had arbitrary rate parameters and no experimental verification. SciFinder searches for other citations of the effect of the reactor surface on oscillatory peroxidase kinetics proved fruitless, although porphines adsorbed on silica catalyze NADH reduction better than the same unsupported catalysts. , The rate of HRP adsorption on glass at pH 6 is similar to the rate at which Olson's oscillatory reactions damped but fails to explain Lvovich's result that adding silica surface area to the PO reaction actually accelerates oxygen consumption . It has long been known that one of the cofactors in the PO reaction, methylene blue (MB), adsorbs on quartz .…”
In experiments on the kinetics of the peroxidase-oxidase oscillatory reaction in pH 5.l acetate buffer, biofilms form in less than 48 h on the quartz reactor surface. The nominally homogeneous peroxidase system shows dynamical changes in response to this biofilm growth, partially explaining subtle differences among dynamics observed over time and between laboratories. Kinetics data and model computations are correlated with micrographs of biofilm formation. It is evident that bare quartz also interacts with reaction species, so that the surface area-to-volume ratio is an important parameter on which observed dynamics depend.
“…20) Acid chloride of Cu-OBTCPP (Cu-OBTCPPCl, see Fig. 1) was synthesized from Cu-OBTCPP as described by Iwado et al 21) The resultant CuOBTCPPCl (ca. 4 mg) was dissolved in dry dioxane (10 ml).…”
HPLC is conventionally used for separation and/or analysis of substances such as medicines, mutagens, environmental pollutants, and the like, which are broadly present in the circumstances. [1][2][3][4][5][6] For such a purpose, an octadecylsilyl silica gel column has still been used as a stationary phase for a preparative purpose. [7][8][9] On the other hand, it has been attempted to separate and/or analyze these substances making use of interactions involving p electron because the substances to be separated or analyzed include poly-aromatichydrocarbons (PAHs) and heterocyclic compounds abundantly. As one of approaches, stationary phases having an ability to interact with PAHs through p electron, that is, stationary phases composed of a support carrying a compound with p electron have been developed. 10) Currently, there are commercially available columns in this form, such as a PYE column whose stationary phase comprises a 2-(1-pyrenyl)ethyl group. The applicability to the separation of PAHs and the like has already been reported. 6,10,11) Metal porphyrin analogs such as metal porphyrin or metal phthalocyanine belong to macrocyclic compounds having a wide spread of p electron cloud. Cu-porphyrin-immobilized silica gels have been reported to be useful as an HPLC stationary phase for separation of compounds having p electron such as PAHs. [12][13][14][15] In addition, columns having ability to exert both the p electronic-and electrostatic-interactions such as a pentabromobenzyloxy propylsilyl silica gel column (PBB column) 16) and a nitrophenylethylsilyl silica gel column (NPE column) 17) have been developed and made commercially available to date.In view of the above, we reached the conception that a novel stationary phase for PAHs and its analogous compounds may be obtained by brominating Cu-tetrakis(4-carboxyphenyl)porphine (Cu-TCPP, see Fig. 1) 18) known to show p-p electron interactions with PAHs, because bromination would destroy the planarity of porphyrin ring and change the polarity, thereby providing Cu-TCPP with an ability to exert additional interaction(s), as is the case with PBB column. In the present research, we prepared silica gels immobilizing Cu-octabromotetrakis(4-carboxyphenyl)porphine derivatives to give a prospective stationary phase (Cu-OBTCPP D ), and elucidated their retention property from various aspects. The research revealed that Cu-OBTCPP D has excellent function based on interactions involving p electron, electrostatic force, and the like, as explained in more detail below.
ExperimentalChemicals and Reagents Tetrakis-(4-carboxyphenyl)porphine (H 2 -TCPP) was obtained from Tokyo Kasei, Japan. As a support, Develosil NH 2 -5 (hereinafter, referred to as "Dev"), which is spherical aminopropyl-silica gels (particle size, 5 mm; specific surface area, 250 m 2 /g; average pore size, 12 nm, amino-group; 98 mmol/g) was purchased from Nomura Kagaku, Japan. As eluents, purified water by Labo IonPure-12 (Millipore, U.S.A.), methanol and n-hexane for HPLC (Nacalai Tesque, Japan) were mainly...
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