Instrumental method for quantitative evaluation of cell or particle adhesion, based on transport measurements in capillary flow

An instrumental method is proposed for the quantitative evaluation of cell/particle adhesion at solid/liquid interfaces. As a measure of adhesion, the retardation of convective transport in capillary flow tubes is determined. The flow tubes, for such purposes, have been internally coated with the substance under investigation. AC-operated electronic gating is applied, preferentially, for the determination of the elution rate. This technique, to some extent, is similar to that of high-pressure liquid chromatography (HPLC). However, the transport mechanism is different as in this case, where transport mainly takes place about halfway between the capillary axis and the wall (Segre-Silberberg effect). At specific flow rates of the carrier liquid, cells/particles repeatedly contact the wall, only to be released again as a consequence of increasing lift and drag. This phenomenon depends on the chemical nature of the capillary wall coating and causes measurable retardation of transport. A transport model is proposed that predicts flow conditions under which transport retardation and adhesive interaction are to be expected. Experiments prove that the Segre-Silberberg effect, i.e., the occurrence of a preferential pathway of transport, is fully established already at capillary lengths of a few decimeters, and that the occurring retardation of transport, if any, is governed by the chemical nature of the capillary wall coatings. The area enclosed between the cumulative elution curves of sample and reference materials offers a reproducible measure of adhesion. The technique is fast, sensitive, and reliable.