Surface active complexes formed between keratin polypeptides and ionic surfactants.
Keratins are a group of important proteins in skin and hair and as biomaterials they can provide desirable properties such as strength, biocompatibility, and moisture regaining and retaining. The aim of this work is to develop water-soluble keratin polypeptides from sheep wool and then explore how their surface adsorption behaves with and without surfactants. Successful preparation of keratin samples was demonstrated by identification of the key components from gel electrophoresis and the reproducible production of gram scale samples with and without SDS (sodium dodecylsulphate) during wool fibre dissolution. SDS micelles could reduce the formation of disulphide bonds between keratins during extraction, reducing inter-molecular crosslinking and improving keratin polypeptide solubility. However, Zeta potential measurements of the two polypeptide batches demonstrated almost identical pH dependent surface charge distributions with isoelectric points around pH 3.5, showing complete removal of SDS during purification by dialysis. In spite of different solubility from the two batches of keratin samples prepared, very similar adsorption and aggregation behavior was revealed from surface tension measurements and dynamic light scattering. Mixing of keratin polypeptides with SDS and C12TAB (dodecyltrimethylammonium bromide) led to the formation of keratin-surfactant complexes that were substantially more effective at reducing surface tension than the polypeptides alone, showing great promise in the delivery of keratin polypeptides via the surface active complexes. Neutron reflection measurements revealed the coexistence of surfactant and keratin polypeptides at the interface, thus providing the structural support to the observed surface tension changes associated with the formation of the surface active complexes.
Biological Physics Group, Schuster Building, Oxford Road, The University of Manchester, Manchester M13 9PL, UK.
Fang
F
Pan
Biological Physics Group, Schuster Building, Oxford Road, The University of Manchester, Manchester M13 9PL, UK.
Zhiming
Z
Lu
Unilever R&D Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, UK.
Ian
I
Tucker
Unilever R&D Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, UK.
Sarah
S
Hosking
Unilever R&D Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, UK; Menara KLK 1, Jalan Pju 7/6, Mutiara Damansara, 47810, Petaling Jaya, Selangor 47800, Malaysia.
Jordan
J
Petkov
Biological Physics Group, Schuster Building, Oxford Road, The University of Manchester, Manchester M13 9PL, UK. Electronic address: J.Lu@manchester.ac.uk.
Jian R
JR
Lu
D000327:Adsorption; D000818:Animals; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007633:Keratins / Q000737:chemistry* / Q000302:isolation & purification; D008823:Micelles; D010455:Peptides / Q000737:chemistry*; D012756:Sheep; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D012995:Solubility; D055672:Static Electricity; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D014935:Wool / Q000737:chemistry
D002593:Cetrimonium Compounds; D004220:Disulfides; D008823:Micelles; D010455:Peptides; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D007633:Keratins; D000077286:Cetrimonium
Keratin polypeptides; Neutron reflection; Protein adsorption; Protein-surfactant complexes; Surface activity; Surface tension