NONSPECIFIC ADHERENCE OF OXIDE PARTICLES AS A MEANS OF QUANTIFYING PROTEIN ADSORPTION ON SURFACES

This paper reports quantification of a method for measuring amounts of protein adsorbed to a surface; the method is especially useful for re vealing macroscopic spatial patterns of adsorption. The experiments te sted the effectiveness of iron oxide suspensions adsorbed onto the ads orbed protein to indicate, in separate trials, the amount of either hu man plasma fibrinogen or human serum albumin (HSA) present on glass sl ides. Corresponding trials, using radioactively labeled proteins, were performed to calibrate the amount of either albumin or fibrinogen ads orbed onto similar slides out of solutions of varying bulk concentrati ons. The oxide deposits were quantified using a scanner and an image a nalysis program. The isotherms produced from the collected data indica te a continuous, monotonic correlation between light absorbed by adher ent oxide and surface concentration of protein. The same correlation a pplies to albumin and fibrinogen when surface concentrations are expre ssed in weight units. These results confirm that patterns of oxide dep osition correspond to patterns of protein deposition and show clearly how qualitative observations, such as those previously reported, can b e made quantitative with scanning and digital image analysis.