Muonium formation and magnetic relaxation in dextran and iron-dextran

Kilcoyne, S.H.; Webster, Brian

doi:10.1002/1097-458x(200006)38:13<::aid-mrc694>3.0.co;2-z

Cited by 6 publications

(11 citation statements)

References 14 publications

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“…The complexes are pharmaceutically important as synthetic substitutes for the iron storage protein ferritin, and it is used in the treatment of iron deficiency anaemias (28). Research shows that irondextran complexes are composed of an iron-based core with a dextran shell (27)(28)(29)(30)(31). At the same time, the adsorption of nonionic surfactants on metal oxides is believed to be a physical process through hydrogen bonding and van der Waals attraction force (32).…”

Section: Partitioning Behavior Of Hematite In the Dextran/triton X-10mentioning

confidence: 99%

“…Although both of these surfactants can modify the surface chemistry of ferric oxide at certain pH values in conventional aqueous solutions, neither one changed the partitioning behavior of hematite in this polymer/surfactant system. Since dextran strongly interacts with ferric oxide (27)(28)(29)(30)(31), it appears that SDS or oleate is not able to replace the strongly adsorbed dextran layer on the hematite surface so that the particles continue to stay in the bottom phase.…”

Section: Effects Of Surfactants On Hematite Partitionmentioning

confidence: 99%

“…Therefore, the hydrophilic hematite particles prefer the bottom phase. At the same time, dextran interacts strongly with ferric oxide in aqueous solution (27)(28)(29)(30)(31). But, there is negligible adsorption of PEG on hematite (43)(44)(45)(46).…”

Section: Partitioning Behavior Of Hematite In the Peg/dextran Systemmentioning

confidence: 99%

“…The effect of SDS on the hematite partition in the PEG/dextran is the same as that in the dextran/Triton X-100 system. Like the polymer/surfactant system, it is difficult for SDS to replace the adsorbed dextran layer since dextran interacts with ferric oxide strongly (27)(28)(29)(30)(31) and SDS only adsorbs on the solid surface physically (34)(35).…”

Section: Partitioning Behavior Of Hematite In the Peg/dextran Systemmentioning

confidence: 99%

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Aqueous Biphase Extraction for Processing of Fine Coal

Osseo-Asare¹,

Zeng²

2001

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Section: Partitioning Behavior Of Hematite In the Dextran/triton X-10mentioning

confidence: 99%

Section: Effects Of Surfactants On Hematite Partitionmentioning

confidence: 99%

Section: Partitioning Behavior Of Hematite In the Peg/dextran Systemmentioning

confidence: 99%

Section: Partitioning Behavior Of Hematite In the Peg/dextran Systemmentioning

confidence: 99%

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Aqueous Biphase Extraction for Processing of Fine Coal

Osseo-Asare¹,

Zeng²

2001

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“…The largest biological molecules that appear to have been investigated using MuSR methods are cytochrome c, 74,75 myoglobin 75 and dextran 76 and an iron-dextran complex. 76 In cytochrome c, it is found that muonium is trapped at the oxygen atom of CNO amino acid groups, where the muon relaxation rate is subject to the influence of electronic dynamics; free muons are predicted to associate with all atoms on the protein chain carrying a negative charge, so addition of both muon and Mu is expected at the CNO oxygen sites. In the heme units, muons are trapped at the pyrrole nitrogen atoms, where they are subject to a 'chemical shift' of 88.4 ppm.…”

Section: Measurements Relevant To An Alternative Mode Of Lipid Damagementioning

confidence: 99%

8 Muon spectroscopy

Rhodes

2001

Annu. Rep. Prog. Chem., Sect. C

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The elusiveness of reactive free radicals poses great challenges for their investigation per se in most processes in which they have an intermediary role; this is true particularly in heterogeneous media. There are, however, methods available for the detection of radicals with enormous sensitivity and specificity which are given the collective acronym mSR (MuSR). All the MuSR methods rely upon the addition of the light hydrogen atom 'muonium' -a hydrogen atom with a radioactive positive muon as its nucleus, having a mass 1 9 that of a protium atom -to an organic substrate. In addition to its property of radioactive decay, the muon also has spin, and therefore experiments akin to those of conventional magnetic resonance experiments may be undertaken. Among the suite of methods thus encompassed is transverse-field MuSR (TF-MuSR), which is equivalent to ENDOR and yields the nucleus (muon) coupling directly, while the avoided level crossing (ALC) approach yields the magnitudes of the couplings from other nuclei present in a given radical, and also their relative signs (like TRIPLE does). Although these are resonance experiments, they do not require the application of external radiofrequency fields; however, radiofrequency experiments are possible, in which the analogies with more conventional magnetic resonance experiments are more direct. However, the experiments which are rendered possible by muons are unique, and have no practicable counterpart in more conventional techniques. In particular, the feature of single-particle-counting methods being used in combination with nuclear spins which are 100% polarised (i.e. vastly in excess of the Boltzmann factor!) permits unparalleled sensitivity regarding reactive radicals. Through the incisiveness of these methods, knowledge in the field of free radical chemistry has been gained that would be unachievable using the more established methods of EPR and its relatives.In consequence of these benefits, although my own background is in EPR (a topic which I have reviewed previously in this series), 1-3 my research group has become increasingly involved in the techniques of MuSR, especially in regard to determining the behaviour of radicals in catalytic systems and in heterogeneous environmental processes, and for the measurement of free radical reaction rates pertinent to biological membrane damage and repair. These are all topics whose investigation we could not have attempted without muons.

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