title: Molecular modeling directed by an interfacial test apparatus for the evaluation of protein and polymer ingredient function in situ.
abstract: A simplified apparatus is described that measures the damping of a suspended measuring device. The movement of the device (bob) is damped by the properties of the air-water surface adsorbed material. Its value lies in describing the surface chemomechanical properties of ingredients and excipients used in food, nutraceutical, cosmetic (cosmeceutical), and natural drug-food product formulations that traverse the food sciences. Two surfactants, two food and drug-grade polymers, and five naturally occurring food and serum proteins were tested and used to estimate and model interfacial viscoelasticity. Equilibration times of >15 min were found to give sufficiently stable interfaces for routine assessment. The viscoelasticity of the air-water interface was estimated with reference to model solutions. These model solutions and associated self-assembled interfacial nanostructured adsorbed layers were fabricated using a preliminary screening process with the aid of a specialized foaming apparatus ( C(300) values), surface tension measurements (23-73 mN/m), and referential surface shear and dilation experiments. The viscoelasticity measured as a percentage of surface damping ( D) of a pendulum was found to range from 1.0 to 22.4% across the samples tested, and this represented interfacial viscosities in the range of 0-4630 microNs/m. The technique can distinguish between interfacial compositions and positions itself as an easily accessible valuable addition to tensiometric and analytical biochemistry-based techniques.
authors.affiliation: Chemical Biology Research Group, School of Pharmacy and Biomolecular Sciences, The University of Brighton, Moulsecoomb Science Campus, Lewes Road, Brighton BN2 4GJ, United Kingdom.
authors.forename: George W
authors.initials: GW
authors.lastname: Collins
authors.forename: Avani
authors.initials: A
authors.lastname: Patel
authors.forename: Alan
authors.initials: A
authors.lastname: Dilley
authors.forename: Dipak K
authors.initials: DK
authors.lastname: Sarker
mesh_terms: D002627:Chemistry, Physical / Q000295:instrumentation*; D003358:Cosmetics / Q000032:analysis; D019587:Dietary Supplements / Q000032:analysis; D004548:Elasticity; D004655:Emulsions / Q000737:chemistry; D005504:Food Analysis / Q000295:instrumentation; D011108:Polymers / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*; D012212:Rheology / Q000295:instrumentation; D013500:Surface Tension; D014783:Viscosity
chemical_list: D003358:Cosmetics; D004655:Emulsions; D011108:Polymers; D011506:Proteins