The Usage of Proteolitic Enzymes Inhibitors in Studies of the Blood Plasma Particle Size Distribution by the Dynamic Light Scattering

Abstract

Dynamic light scattering (DLS) can be used to obtain the particle size distribution in various human liquids (e.g. saliva, blood samples - plasma, serum, etc.) in order to carry out diagnostic of some diseases. However the effect of proteolytic enzymes on the peptides compounds causes to a continuously changing of particle size distribution with time after blood donation. To stabilize the size distribution pattern the proteolytic enzymes inhibitors should be added to the blood samples.The aims of this study are to obtain the particle size distribution in blood plasma with adding of proteolytic enzyme inhibitors solution (Sigma-Aldrich No. P2714) and in the absence of it by methods of DLS.Two samples of blood were collected from each of healthy non-smoking volunteers (n=6): one sample was with the proteolytic enzymes inhibitors and another without it. Fresh plasma was prepared from each blood sample by centrifugation through 3-4 hours after donation.The results were obtained using an experimental set-up for DLS consisting of a laser beam (633 nm) and a Digital Real-Time Correlator “PhotocorFC”. The DynaLS code provided results graphically in the form of scattering light intensity distribution on particles sizes.Particle size distributions for each sample were obtained through 6 hours after its donation. These distributions were proved to significantly differ at the big sizes region. The particles had significantly larger diameters in samples with adding enzymes inhibitors (996 - 1985 nm) than in the samples without it (492 - 785 nm). We believe that these results could be an evidence of particles splitting processes slow down. Subsequent measurements through 9 hours after donation confirmed the slowing of decay of the biggest particles of blood plasma.