DETERMINATION OF PLASMA-PROTEIN ADSORPTION ON MAGNETIC IRON-OXIDES - SAMPLE PREPARATION

Purpose. The purpose of this study was to investigate the influence of the sample preparation on the plasma protein adsorption pattern of po lysaccharide-stabilized iron oxide particles by two-dimensional polyac rylamide gel electrophoresis (2-D PAGE). Methods. The iron oxide parti cles were incubated in vitro in human plasma for five minutes. Thereaf ter, four different methods for particle recovery, including adsorbed proteins from surplus plasma, were investigated: centrifugation, magne tic separation, gel filtration and membrane-based static microfiltrati on. Adsorbed proteins were desorbed from the particle surfaces by surf actants and analyzed by 2-D PAGE, as described elsewhere (1,2). Result s. All the techniques investigated were able to separate small-size ir on oxides (approx. 110 nm) and adsorbed proteins from excess plasma. T he gels obtained by the different separation procedures displayed almo st identical adsorption patterns. Major proteins identified were: fibr inogen, IgG, albumin and an unclassified protein of about 70 kDa with a pi value of 6.5-7.5. Conclusions, Centrifugation was regarded as the most suitable separation method due to its speed and ease of use. In contrast to gel filtration, any washing media can be used. The magneti c separation process is restricted to particles with high inducible ma gnetic saturation, in particular, to iron oxides with overall sizes > 50 nm.