For biotechnological applications colloids must be brought into contact with biological fluids, either in vivo � as carrier for drug delivery, or in vitro � for protein detection in diagnosis. For such applications, non-specific surface coverage by proteins plays a critical role; governing the elimination time by organisms for the drug delivery or promoting the availability of antibodies in the case of diagnosis. Despite being known for several decades the phenomenon of protein binding to colloids is still not well understood. For example variations in the amount of protein adsorbed from bulk concentration are often observed and fitted with a Langmuir model, even though irreversibility is observed. Our study began with the most abundant protein in serum: albumin. By using fluorescent labelling, we have been able to describe its adsorption on silica colloids with a simple model: albumins adsorb on silica beads until a complete monolayer is attained. Building upon this we investigated how the maximum number of albumins adsorbed per bead depends on pH and ionic strength. The results obtained from this study should enable the design of new systems for diagnosis, which are less susceptible to non-specific aggregation, thereby improving the detection limit of immuno-aggregation based tests.

Colloidal surfaces in biological media

246th National Meeting (2013)

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