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Lipid Film (lipid + film)

Distribution by Scientific Domains

Medical Sciences	50%
Life Sciences	50%

Selected Abstracts

Human synthetic sebum formulation and stability under conditions of use and storage

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2009
P. W. Wertz
Synopsis The human skin surface and hair are generally coated with a thin film of liquid phase sebaceous lipids. This surface lipid film contributes to the cosmetic properties of the skin. Synthetic sebum has been used for studies on properties of skin and hair. However, there has been no standardized formulation of synthetic sebum and many of the synthetic sebum formulations that have been used do not closely resemble actual sebum. In this study, a formulation for a standardized and inexpensive synthetic sebum is proposed, and the chemical stability of this lipid mixture is demonstrated under conditions of use and storage. The proposed synthetic sebum consists of 17% fatty acid, 44.7% triglyceride, 25% wax monoester (jojoba oil) and 12.4% squalene. This lipid mixture takes up approximately 6% of its weight in water when equilibrated in an atmosphere saturated with water vapour. It is stable on exposure to the atmosphere at 32°C for at least 48 h, and it is also stable on storage at 4 or ,20°C, either dry or in chloroform : methanol solution for at least 6 months. This synthetic sebum could be useful in studies on cosmetic properties of the skin surface or hair, on penetration of chemicals into the skin or in development of standardized tests of laundry detergent performance. Résumé La surface de la peau et les poils de l'être humain sont généralement enduits d'un mince film de lipides sébacés en phase liquide. Ce film lipidique de surface contribue aux propriétés esthétiques de la peau. Bien que du sébum synthétique ait été employéà des fins d'études sur les propriétés de la peau et des poils, il n'en éxiste pas de formulation standardisée. Plusieurs des formulations utilisées ne ressemblent pas au sébum naturel. La présente étude propose une formulation standardisée et peu coûteuse d'un sébum synthétique; elle vise aussi à démontrer sa stabilité chimique dans des conditions d'utilization et de stockage. Le sébum synthétique tel que proposé est composé de 17% d'acides gras, de 44.7% de triglycérides, de 25% d'un mono ester de cire (huile de jojoba) et de 12.4% de squalène. Ce mélange lipidique prend environ 6% de son poids dans l'eau lorsqu'il est équilibré dans une atmoshpère saturée en vapeur d'eau. Le mélange demeure stable pendant au moins 48 heures lorsque éxposéà une atmoshpère de 32o. Il le demeure également dans des conditions de stockage de 4oà,20oà sec ou en solution de chloroforme:méthanol pendant au moins 6 mois. Ce sébum synthétique pourrait être utile àétudier les propriétés esthétiques de la surface de la peau et des poils ou de la pénétration cutanée de produits chimiques. Il pourrait aussi servir àélaborer des tests standardisés de rendement des détergents de lessive. [source]

Invertase-Lipid Biocomposite Films: Preparation, Characterization, and Enzymatic Activity

BIOTECHNOLOGY PROGRESS, Issue 1 2004
Sumant Phadtare
The formation of biocomposite films of the industrially important enzyme invertase and fatty lipids under enzyme-friendly conditions is described. The approach involves a simple beaker-based diffusion protocol wherein invertase diffuses into the cationic lipid octadecylamine during immersion of the lipid film in the enzyme solution. Entrapment of invertase in the octadecylamine film is highly pH-dependent, underlining the role of attractive electrostatic interactions between the enzyme and the lipid in the biocomposite film formation. The kinetics of formation of the enzyme-lipid biocomposites has been studied by quartz crystal microgravimetry (QCM) measurements. The stability of the enzyme in the lipid matrix was confirmed by fluorescence spectroscopy and biocatalytic activity measurements. The biocatalytic activity of the invertase-lipid biocomposite films was comparable to that of the free enzyme in solution and showed marginally higher temperature stability. Particularly exciting was the excellent reuse characteristics of the biocomposite films, indicating potential industrial application of these films. [source]

Tear-film lipid layer morphology and corneal sensation in the development of blinking in neonates and infants

JOURNAL OF ANATOMY, Issue 3 2005
John G. Lawrenson
Abstract The aim of the study was to evaluate the role of lipid layer thickness and corneal sensation in the development of blinking in neonates. The study group comprised sixty-four neonates and infants (mean age 27.5 ± 15 (sd) weeks, range 3.4,52) whose mothers were attending a general practice healthy baby clinic. Spontaneous eye-blink activity was determined from digital videographic recordings; tear film lipid layer morphology wasexamined using interference patterns produced by the Keeler TearscopeÔ Plus over a five-point grading scale (higher grades are associated with thick and stable lipid films); corneal sensation threshold was assessed with the Non-Contact Corneal Aesthesiometer (NCCA), using the eye-blink response as an objective indication that the cooling stimulus had been felt; palpebral aperture dimensions were measured using calibrated digital still images of the eye in the primary position. The overall mean spontaneous blink-rate was found to be 3.6 (± 0.3) blinks min,1, and the mean interblink time was 21.6 (± 2.8) s. The lowest blink-rates were observed in the 0,17-week age group (average 2 blinks min,1). The blink-rate showed a highly significant correlation with age (r = 0.46, P < 0.01). The overall mean lipid layer grading was 3.6 (± 0.2 SE) arbitrary units. Higher grades were found in the newborn and the mean grading score reduced with age (P < 0.01). The mean sensation threshold to blink (TTB) was 0.69 (0.04 SE) mbar, which did not differ from a control group of older subjects (P > 0.05). There was a rapid increase in palpebral aperture length and width from birth to 1 year old, with surface area increasing by 50% over the same period. We concluded that the low rate of spontaneous eye blink activity in neonates is associated with a thick stable lipid layer that may be a function of a small palpebral aperture. Furthermore, neonates appear to have the capacity to detect ocular surface cooling, which is a major trigger for spontaneous blinking. [source]

Sample preparation procedures for biological atomic force microscopy

JOURNAL OF MICROSCOPY, Issue 3 2005
K. EL KIRAT
Summary Since the late 1980s, atomic force microscopy (AFM) has been increasingly used in biological sciences and it is now established as a versatile tool to address the structure, properties and functions of biological specimens. AFM is unique in that it provides three-dimensional images of biological structures, including biomolecules, lipid films, 2D protein crystals and cells, under physiological conditions and with unprecedented resolution. A crucial prerequisite for successful, reliable biological AFM is that the samples need to be well attached to a solid substrate using appropriate, nondestructive methods. In this review, we discuss common techniques for immobilizing biological specimens for AFM studies. [source]