Staff PhD

Quartz crystal microbalance with dissipation analysis of interactions between specific milk

Søren Bang Nielsen

Background

The concept of functional foods targets human health beyond (mal)nutrition. The importance of

specific molecular interactions between food-derived components and our primary epithelial barrier

of the gastro-intestinal (GI) surface is, however, incompletely understood. Thus, a number of

bioactive peptides that are released during GI digestion have been claimed to be beneficial for

human health, whereas other bio-active milk proteins are resistant to digestion. The in vivo

relevance is, however, often questionable. Description of interactions between food molecules and

our genome though the expressed proteome in combination with bioassays documenting an effect is

imperative in future food research. We wish to accelerate this research area by focusing on the GI

interface and create innovative techniques for discovering novel molecular interactions of potential

importance.

Aim

We propose to advance research on molecular interactions between specific food-derived

components and the intestinal brush border membrane through an innovative use of the quartz

crystal microbalance with dissipation (QCM-D). Preliminary experiments indicate that this

approach is feasible.

Research Outline

The research is focused on the construction of a biosensor for identification of bioactive components in foods which interact specifically with the brush border membrane (BBM) of the small intestine using colostrum as model food. Brush border membrane vesicles (BBMV) are prepared by published methods and immobilized on quartz crystals either as intact BBMVs or reconstituted BBM proteins in either natural or synthetic lipids in order to induce vesicle collapse to form supported lipid bilayers on the crystal surface. Thus, the surface of the quartz crystal is functionalized to mimic the surface of the small intestine.

Interactions between the BBM and specific milk components and proteolytic fragments hereof are identified by coupling chromatographic separation of the components with online detection of molecular interactions using the quartz crystal microbalance technique.

Bioactive components are identified by mass spectroscopic methods and their effects are validated using complementary methods including cellular models, fluorescence spectroscopy/microscopy and field-flow fractionation with dynamic and static light scattering.