Biomedical subjects

M Leser

Publications and source records attributed to M Leser.

3 recordsLinked to original sources

PubMed2004

Determination of protein adsorption by comparative drop and bubble profile analysis tensiometry.

Proteins adsorb at a liquid interface at very low bulk concentrations which is significantly decreased due to the adsorbed amount. Depending on the surface area A to solution bulk volume V ratio this loss in protein can be significant. Using experimental methods with large differences in the A/V ratio the adsorbed amount can be determined from the measured quantities, for example the surface tension. For beta-casein and bovine and human serum albumin data from literature obtained by the Wilhelmy technique and own data measured by drop profile analysis tensiometry are used. The adsorbed amounts measured directly from ellipsometry agree very well with those determined by the proposed method.

Adsorption↗

PubMed2004

Competitive adsorption from mixed nonionic surfactant/protein solutions.

A thermodynamic model is derived which is suitable to describe adsorption from a mixed protein/surfactant solution. The comparison with experimental data for HSA mixed with the nonionic surfactant decyl dimethyl phosphine oxide shows good agreement. Some model calculations are discussed in terms of the competitive character of the process of adsorption from mixed protein/surfactant solutions. The behavior of globular (HSA) and flexible (beta-casein) proteins appears to be quite different due to the possibility of changing the molar area of adsorbed protein molecules.

Adsorption↗

PubMed2002

Structure, dynamics, and optical properties of concentrated milk suspensions: an analogy to hard-sphere liquids.

A systematic study of the effects of volume fraction increment on the optical properties, the structure, and the dynamics of the casein micelles and fat droplets in milk was performed using diffusing wave spectroscopy. Four types of milk were investigated, NIDO full fat milk, fat-free milk, whey and fat-free milk, and finally lactose and fat-free milk. Independent measurements to calculate the dependence of the viscosity and the index of refraction of the milk serum and casein micelles as a function of the volume fraction were also performed. We compare the experimentally determined quantities photon transport mean free path (l*) and self-diffusion coefficient D(s) with the predictions from theoretical calculations using classical colloidal models such as a hard-sphere fluid. We demonstrate that all types of milk with and without fat content behave, structurally, like colloidal hard-sphere systems up to volume fractions well over 45%. In the case of dynamic measurements, both lactose- and fat-free and whey- and fat-free milk behave also like hard-sphere systems whereas fat-free milk and fat-containing NIDO milk deviate slightly at volume fractions over 35%. Finally, a comparative measurement and theoretical calculation of the casein micelle's size was performed.

Animals↗