Kinetics of the Formation of the Ferric Thiocyanate Complex

Below, John F.; Connick, Robert E.; Coppel, Claude P.

doi:10.1021/ja01545a015

Cited by 88 publications

(34 citation statements)

References 11 publications

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“…Since copper and iron ions were involved in the fabrication process, it is important to make sure that these ions are completely removed to avoid any heavy metal-induced toxicity in further in vivo studies. We used a classical colorimetric approach using ammonia 52 to test residual copper and thiocyanate ions 53 to test residual iron in the hydrogel tubules. No signal was detected by the spectrophotometer for either copper or iron ions, which indicated that the as-prepared hydrogel tubules do not contain significant amounts of copper or iron.…”

Section: Resultsmentioning

confidence: 99%

Freestanding 3-D microvascular networks made of alginate hydrogel as a universal tool to create microchannels inside hydrogels

Sun

Liu

et al. 2016

Biomicrofluidics

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The diffusion of molecules such as nutrients and oxygen through densely packed cells is impeded by blockage and consumption by cells, resulting in a limited depth of penetration. This has been a major hurdle to a bulk (3-D) culture. Great efforts have been made to develop methods for generating branched microchannels inside hydrogels to support mass exchange inside a bulk culture. These previous attempts faced a common obstacle: researchers tried to fabricate microchannels with gels already loaded with cells, but the fabrication procedures are often harmful to the embedded cells. Herein, we present a universal strategy to create microchannels in different types of hydrogels, which effectively avoids cell damage. This strategy is based on a freestanding alginate 3-D microvascular network prepared by in-situ generation of copper ions from a sacrificial copper template. This alginate network could be used as implants to create microchannels inside different types of hydrogels. This approach effectively addresses the issue of cell damage during microfabrication and made it possible to create microchannels inside different types of gels. The microvascular network produced with this method is (1) strong enough to allow handling, (2) biocompatible to allow cell culturing, and (3) appropriately permeable to allow diffusion of small molecules, while sufficiently dense to prevent blocking of channels when embedded in different types of gels. In addition, composite microtubules could be prepared by simply pre-loading other materials, e.g., particles and large biomolecules, in the hydrogel. Compared with other potential strategies to fabricate freestanding gel channel networks, our method is more rapid, low-cost and scalable due to parallel processing using an industrially massproducible template. We demonstrated the use of such vascular networks in creating microchannels in different hydrogels and composite gels, as well as with a cell culture in a nutrition gradient based on microfluidic diffusion. In this way, the freestanding hydrogel vascular network we produced is a universal functional unit that can be embedded in different types of hydrogel; users will be able to adopt this strategy to achieve vascular mass exchange in the bulk culture without changing their current protocol. The method is readily implementable to applications in vascular tissue regeneration, drug discovery, 3-D culture, etc. Published by AIP Publishing. [http://dx

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Section: Resultsmentioning

confidence: 99%

Freestanding 3-D microvascular networks made of alginate hydrogel as a universal tool to create microchannels inside hydrogels

Sun

Liu

et al. 2016

Biomicrofluidics

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“…Lines of regression through the points a t each temperature, ignoring those for concentrations of hydrogen ion in excess of 0.2 i M a t 20 and 25 "C, have slopes implying, through eq. [4], values for k1 + k3 listed in Table 11. Cursory exainination of Fig.…”

Section: Results Of T H E Kinetic Measurements and Discussionmentioning

confidence: 99%

The Mono-Oxalato Complexes of Iron(iii): Part Ii. Kinetics of Formation

Bauer¹,

Smith²

1965

Can. J. Chem.

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The kinetics of the formation of the mono-oxalato complexes of iron(II1) have been examined spectrophotometrically over the range of temperatures 5 to 25 "C in an aqueous medium of ionic strength 0.50 and the range of hydrogen ion concentrations 0.03 to 0.45 M . The kinetically significant paths under the conditions studied involve reactions first order in iron(II1) and in bioxalate but there appears to be some decrease in the second order rate constant with increase in hydrogen ion concentration a t the highest acidities and a t the highest temperatures. Although there is no significant contribution to the rate by a n acid-independent path first order in free oxalate under the experimental conditions, the possibility of the rate constant for such a path being greater than that first order in bioxalate is not precluded.

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“…In solution, Fe 3ϩ was estimated by measuring the absorbance of [Fe(SCN)] aq 2ϩ (ε ϭ 5000  Ϫ1 cm Ϫ1 ) at 460 nm after the addition of NH 4 SCN solution. [11,12] The free-acid content in both of these iron solutions were measured by passing them separately through a Dowex 50 W X-8 strong cation-exchange resin in the H ϩ form to obtain [H ϩ ] equivalent to the metal-ion concentration along with free acid and then subtracting the metal equivalent from these. An aqueous solution of NaClO 4 (G. R., E. Merck) was standardised by passing through a Dowex 50 W X-8 strong cation-exchange resin in the H ϩ form and titrating the liberated acid with standard NaOH to a phenolphthalein end-point.…”

Section: Methodsmentioning

confidence: 99%

“…Here, Fe 2ϩ hydrolysis is neglected and replaced by the deprotonation equilibrium of 1. (12) (13) (14) (15) (16) Proceeding in the same way as above gives…”

Section: Full Papermentioning

confidence: 99%

Kinetics and Mechanism of Oxidation of Fe²⁺ by the Tris(biguanide)manganese(IV) Ion in Aqueous Acid Media

et al. 2004

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Tris(biguanide)manganese(IV), [Mn(LH2)3]4+ (LH2 = biguanide, C2N5H7), quantitatively oxidises Fe2+ to Fe3+ and is itself reduced to Mn2+ with almost quantitative (> 95%) release of biguanide. The reaction rate strongly depends on added Fe3+; in the presence of externally added Fe3+, the reaction shows a clear first‐order dependence in [MnIV], whereas in the absence of any added Fe3+, an initial quick loss of MnIV is associated with a subsequent very sluggish decay. Two consecutive one‐electron transfer inner‐sphere steps are proposed for the entire redox process where [Mn(LH2)3]3+, the initial one‐electron‐reduced product of MnIV, is believed to be a steady‐state intermediate. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Kinetics of the Formation of the Ferric Thiocyanate Complex

Cited by 88 publications

References 11 publications

Freestanding 3-D microvascular networks made of alginate hydrogel as a universal tool to create microchannels inside hydrogels

Freestanding 3-D microvascular networks made of alginate hydrogel as a universal tool to create microchannels inside hydrogels

The Mono-Oxalato Complexes of Iron(iii): Part Ii. Kinetics of Formation

Kinetics and Mechanism of Oxidation of Fe²⁺ by the Tris(biguanide)manganese(IV) Ion in Aqueous Acid Media

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Kinetics of the Formation of the Ferric Thiocyanate Complex

Cited by 88 publications

References 11 publications

Freestanding 3-D microvascular networks made of alginate hydrogel as a universal tool to create microchannels inside hydrogels

Freestanding 3-D microvascular networks made of alginate hydrogel as a universal tool to create microchannels inside hydrogels

The Mono-Oxalato Complexes of Iron(iii): Part Ii. Kinetics of Formation

Kinetics and Mechanism of Oxidation of Fe2+ by the Tris(biguanide)manganese(IV) Ion in Aqueous Acid Media

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Kinetics and Mechanism of Oxidation of Fe²⁺ by the Tris(biguanide)manganese(IV) Ion in Aqueous Acid Media