An Easily Demonstrated Zero-Order Reaction in Solution

Hindmarsh, K. W.; House, Donald A.

doi:10.1021/ed073p585

Cited by 7 publications

(5 citation statements)

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“…As will be shown later, this is in contrast to the more common cases of first-and second-order reactions, where t 1/2 is either constant (first order) or inversely proportional to the initial reagent concentration (second order). According to Hindmarsh and House [47], "zero-order reactions are chemical kinetics curiosities. In most textbooks, they are only briefly mentioned before rapidly passing to first-order reactions.…”

Section: Zero-ordermentioning

confidence: 99%

Practical Chemical Kinetics in Solution

Seoud

Baader

Bastos

2016

Encyclopedia of Physical Organic Chemistry, 5 Volume Set

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Section: Zero-ordermentioning

confidence: 99%

Practical Chemical Kinetics in Solution

Seoud

Baader

Bastos

2016

Encyclopedia of Physical Organic Chemistry, 5 Volume Set

View full text Add to dashboard Cite

“…When the dissolution follows zero-order kinetics, the rate of reaction will be independent of the concentration(s) of the reactant(s) and therefore the rate law will be expressed as follows: where M 0 is the concentration of the reactant, t is the time of the reaction and the rate of reaction is equal to the rate constant, k. Depending on the units of concentration, k will have units of mole per volume per time or mass per volume per time (such as (mol/dm 3 )/s or (g/dm 3 )/s). An example of a zero-order chemical reaction is the oxidation of tetrachloroplatinate (II) (PtCl 4 2− ) in excess of persulphate ion (S 2 O 8 2− ) in acidic conditions (HCl) where the reaction kinetics was found to be independent of the concentration of S 2 O 8 2− (5 – 50 mM) [ 63 ].…”

Section: Introductionmentioning

confidence: 99%

Dissolution and biodurability: Important parameters needed for risk assessment of nanomaterials

et al. 2015

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Biopersistence and biodurability have the potential to influence the long-term toxicity and hence pathogenicity of particles that deposit in the body. Therefore, biopersistence and biodurability are considered to be important parameters needed for the risk assessment of particles and fibres. Dissolution, as a measure of biodurability, is dependent on the chemical and physical properties (size, surface area, etc.) of particles and fibres and also of the suspension medium including its ionic strength, pH, and temperature. In vitro dissolution tests can provide useful insights as to how particles and fibres may react in biological environments; particles and fibres that release ions at a higher rate when suspended in vitro in a specific simulated biological fluid will be expected to do so when they exist in a similar biological environment in vivo. Dissolution of particles and fibres can follow different reaction kinetics. For example, the majority of micro-sized particles and fibres follow zero-order reaction kinetics. In this case, although it is possible to calculate the half-time of a particle or fibre, such calculation will be dependent on the initial concentration of the investigated particle or fibre. Such dependence was eliminated in the shrinking sphere and fibre models where it was possible to estimate the lifetimes of particles and fibres as a measure of their biodurability. The latter models can be adapted for the dissolution studies of nanomaterials. However, the models may apply only to nanomaterials where their dissolution follows zero-order kinetics. The dissolution of most nanomaterials follows first-order kinetics where dependence on their initial concentration of the investigated nanomaterials is not required and therefore it is possible to estimate their half-times as a measure of their biodurability. In dissolution kinetics for micro-sized and nano-sized particles and fibres, knowledge of dissolution rate constants is necessary to understand biodurability. Unfortunately, many studies on dissolution of nanoparticles and nanofibres do not determine the dissolution rates and dissolution rate constants. The recommendation is that these parameters should be considered as part of the important descriptors of particle and fibre physicochemical properties, which in turn, will enable the determination of their biodurability.

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“…Using either approach, the reported trends in the experimental results were the same. The reaction kinetics were evaluated according to reaction rate laws, , and details are provided in Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

Scalable Nanogap Sensors for Non-Redox Enzyme Assays

Tayebi

Credo

et al. 2018

ACS Sens.

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Clinical diagnostic assays that monitor redox enzyme activity are widely used in small, low-cost readout devices for point-of-care monitoring (e.g., a glucometer); however, monitoring non-redox enzymes in real-time using compact electronic devices remains a challenge. We address this problem by using a highly scalable nanogap sensor array to observe electrochemical signals generated by a model non-redox enzyme system, the DNA polymerase-catalyzed incorporation of four modified, redox-tagged nucleotides. Using deoxynucleoside triphosphates (dNTPs) tagged with para-aminophenyl monophosphate (pAPP) to form pAP-deoxyribonucleoside tetra-phosphates (AP-dN4Ps), incorporation of the nucleotide analogs by DNA polymerase results in the release of redox inactive pAP-triphosphates (pAPP) that are converted to redox active small molecules para-aminophenol (pAP) in the presence of phosphatase. In this work, cyclic enzymatic reactions that generated many copies of pAP at each base incorporation site of a DNA template in combination with the highly confined nature of the planar nanogap transducers ( z = 50 nm) produced electrochemical signals that were amplified up to 100,000×. We observed that the maximum signal level and amplification level were dependent on a combination of factors including the base structure of the incorporated nucleotide analogs, nanogap electrode materials, and electrode surface coating. In addition, electrochemical signal amplification by redox cycling in the nanogap is independent of the in-plane geometry of the transducer, thus allowing the nanogap sensors to be highly scalable. Finally, when the DNA template concentration was constrained, the DNA polymerase assay exhibited different zero-order reaction kinetics for each type of base incorporation reaction, resolving the closely related nucleotide analogs.

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An Easily Demonstrated Zero-Order Reaction in Solution

Cited by 7 publications

References 0 publications

Practical Chemical Kinetics in Solution

Practical Chemical Kinetics in Solution

Dissolution and biodurability: Important parameters needed for risk assessment of nanomaterials

Scalable Nanogap Sensors for Non-Redox Enzyme Assays

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