The nature of Covalently bound fatty acids in wool fibres

Negri, AP; Hj, Cornell; De, Rivett

doi:10.1071/ar9911285

Cited by 65 publications

(26 citation statements)

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“…Jones et al (1996) suggested that the 30% difference in bound acids removed by potassium t-butoxide and KOH treatments could be due to $30% of the bound lipid trapped within the protein layer adjacent to the outer surface and edges of the cuticle cell. However, an equally tenable explanation for this observation is that the difference could be due to the inaccessible lipid bound to the surface of cuticle cells underlying cuticle cells at the fibre surface, as suggested by Negri et al (1991), which the surface specific potassium t-butoxide treatment will not be able to access and release. This…”

Section: Conclusion and Broader Discussionmentioning

confidence: 86%

“…Tentative nature of assignments While the assignments of some of the acid species in the ToF-SIMS spectra, Table 1, are tentative, the ToF-SIMS mass spectrometric data does not distinguish between normal, iso or anteiso isomers of acids of the same carbon number, the presence of the dominant anteiso fatty acid 18-methyleicosanoic acid has been confirmed by various independent techniques (Negri et al, 1991). The other odd numbered acids observed in this work may also be 'anteiso' acids like 18-methyleicosanoic acid but even numbered acids have not been classified with respect to any branching in the alkyl chains.…”

Section: Calculated Quantities Of Bound Surface Acids In Untreated Famentioning

confidence: 79%

“…The underlying protein component of this proteolipid structure is often referred to as the epicuticle. The fatty acids are dominated by 18-methyleicosanoic acid, a branched anteiso fatty acid with the structural formula CH 3 CH 2 CH(CH 3 )CH 2 (CH 2 ) 14 CH 2 COOH, where the alkyl chain is terminated by a secondary butyl group (Negri, Cornell, & Rivett, 1991).…”

Section: Introductionmentioning

confidence: 99%

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Characterisation of the bound lipids at the wool fibre surface by time of flight secondary ion mass spectrometry (ToF-SIMS)

Rankin

Carr

2013

Journal of The Textile Institute

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Negative ion time of flight secondary ion mass spectrometry (ToF-SIMS) analysis of rigorously cleaned untreated, hydroxylamine and potassium hydroxide (KOH)-treated wool fabrics, produced with minimal finishing, has revealed the possible presence of hitherto unidentified bound acids at the surface of the wool fibre. Spectral peaks have been assigned to C 8 through to C 22 fatty acids, the odd numbered acids of which have been assigned to anteiso acids, (a), akin to the anteiso acid 18-methyleicosanoic acid known to be the dominant fatty acid bound to keratin fibre surfaces. This has included the assignment of some small peaks to hydroxylated aC 18 H 36 (OH)COS À and aC 20 H 40 (OH)COS À species, where the hydroxyl group is attached to the asymmetric 16 or 18 numbered carbon atom in the alkyl chain, respectively. The study has confirmed that many of the acids are bound to the fibre surface by thioester linkages (about 70%) and that the remainder is bound by oxygen ester acyl linkages. ToF-SIMS analysis of hydroxylaminetreated wool has confirmed the removal of all the thioester bound surface lipids, as well as lesser quantities but not all of the acyl bound lipids. In contrast, a 2 h KOH treatment removes all surface accessible bound lipids. Positive ion ToF-SIMS spectral analyses have not proved useful in characterising the possibly thiol rich fibre surface remaining after hydroxylamine treatment. The formation of characteristic immonium ions from surface cysteine residues after hydroxylamine treatment has been shown not to occur for free cysteine and so is unlikely to occur for such residues at the wool fibre surface. Scanning electron microscopy and transmission electron microscopy analyses have also been performed to assess the extent of the hydroxylamine reaction with the fibre. The implications of these findings for currently proposed models of the wool fibre surface, and for exploiting reactions of hydroxylamine followed by other electrophilic reagents to produce modified wool surfaces, are also discussed.

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Section: Conclusion and Broader Discussionmentioning

confidence: 86%

Section: Calculated Quantities Of Bound Surface Acids In Untreated Famentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

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Characterisation of the bound lipids at the wool fibre surface by time of flight secondary ion mass spectrometry (ToF-SIMS)

Rankin

Carr

2013

Journal of The Textile Institute

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“…18-MEA levels were found to comprise approximately 50% of total bound FA in surface cleaned wool fabric, lower than the 70% value reported in the literature for raw wool [5]. Wool fabric would be expected to have a modified surface lipid content relative to raw wool, as it has undergone additional processing.…”

Section: Methanolic Hydroxidementioning

confidence: 78%

Covalent Modification of the Wool Fiber Surface: Removal of the Outer Lipid Layer

Meade¹,

Dyer²,

Caldwell³

et al. 2008

Textile Research Journal

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This investigation provided a comparative assessment of strategies for the removal of 18-methyleicosanoic acid (18-MEA), and other surface bound lipids enveloping the wool fiber surface, by chemical and physical cleavage of the thioester bond. The removal of this lipid layer reveals an underlying proteinaceous layer, exposing functional chemical groups available for covalent attachment of new molecular or nanoparticulate entities by chosen treatments. Lipid removal treatments employing methanolic potassium hydroxide, t-butoxide in t-butanol, and aqueous hydroxylamine and a physical atmospheric pressure glow discharge (APGD) plasma treatment were compared. Treated wool fabrics were subsequently characterized by analysis of the exposed groups on the fiber surface by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), with the bulk surface properties of the fabrics assessed employing wettability testing techniques. An evaluation of chemical and plasma methods for removal of the surface bound lipid layer resulted in the selection of aqueous hydroxylamine/ non-ionic surfactant as the optimal treatment method for subsequent covalent attachment of novel entities by surface treatments. Optimized aqueous hydroxylamine treatment was found to remove up to 77% of the surface bound 18-MEA, providing a marked increase in surface wettability, without significantly affecting the handle of the treated fabric. Surface characterization demonstrated that the hydroxylamine treatment produces an increase in surface friction, with uniform and controlled removal of the surface lipid layer, and minimal surface oxidation of the surface thiols. Minimizing surface oxidation of thiols was a critical target of surface lipid removal in this study, as it maximizes the potential for subsequent surface modification via covalent attachment. The use of aqueous conditions, short reaction times, and moderate temperatures with hydroxylamine treatment are advantageous in comparison with treatments employing non-aqueous solvents such as methanol and anhydrous t-butanol. The economic and environmental advantages of an aqueous, effective, and non-damaging approach to surface lipid removal highlight this approach as a potential avenue for future textile application of novel wool surface chemistries.

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“…This fatty layer has a thickness ranging from 2 to 10 nm and is accounted for about 70% by 18-methylecoicosanoic acid and the other 30% by other covalently bound fatty acids including palmitic, oleic, stearic and eicosanoic acid (Negri et al, 1991). The active species contained in the plasma lead to a chemical etching oxidising action.…”

Section: Wettabilitymentioning

confidence: 99%

The effect of an innovative atmospheric plasma jet treatment on physical and mechanical properties of wool fabrics

Ceria

Rombaldoni

Rovero

et al. 2010

Journal of Materials Processing Technology

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The nature of Covalently bound fatty acids in wool fibres

Cited by 65 publications

References 0 publications

Characterisation of the bound lipids at the wool fibre surface by time of flight secondary ion mass spectrometry (ToF-SIMS)

Characterisation of the bound lipids at the wool fibre surface by time of flight secondary ion mass spectrometry (ToF-SIMS)

Covalent Modification of the Wool Fiber Surface: Removal of the Outer Lipid Layer

The effect of an innovative atmospheric plasma jet treatment on physical and mechanical properties of wool fabrics

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