Andrei Lugovtsov , Vyacheslav Kochubey [2, 3], Alexander Priezzhev [1, 4], Valery Tuchin [2, 3, 5]
 International Laser Center, M.V. Lomonosov Moscow State University, Leninskye Gory 1-62, 119991
Moscow, Russian Federation
 Research-Education Institute of Optics and Biophotonics, Saratov National Research State University, Astrakhanskaya 83, 410012 Saratov, Russian Federation
 Interdisciplinary Laboratory of Biophotonics, National Research Tomsk State University, Lenin’s av. 36, 634050 Tomsk, Russian Federation
 Department of Physics, M.V. Lomonosov Moscow State University, Leninskye Gory 1-2, 119991
Moscow, Russian Federation
 Laboratory of Laser Diagnostics of Technical and Living Systems, Institute of Precision Mechanics and Control RAS, Rabochaya 24, 410028 Saratov, Russian Federation
Iron (iii) oxide nanoparticles (Fe2O3) have been proposed for using in various biological and bio-medical applications. For example, the particles are promising for biomedical imaging and photodynamic therapy (PDT) of oncology diseases. Recently, the Fe2O3 nanoparticles with surface functionalization by porphyrins (Fe2O3-POR) were proposed as more efficient for PDT since they strongly absorb light, which is then converted to energy and heat in the illuminated areas. It is presumed that in order to reach the target these particles would be administered into blood. Although Fe2O3 nanoparticles are considered as biocompatible and non-toxic, so far there is little information on the interaction of the particles with major blood components. The aim of this work was to estimate the in vitro effect of Fe2O3 particles on blood microrheology properties. The ability of red blood cells (RBCs) to deform in shear flow was characterized by shear stress dependence of the deformability index. The ability to spontaneously aggregate in whole blood was characterized by the time of aggregates formation and aggregation amplitude (the number of aggregated RBC at rest in percents). The hydrodynamic strength of aggregates was assessed also.
In this work, all measurements were performed by means of the laser diffractometry and aggregometry techniques by using the commercially available Rheoscan system (Rheomeditech, Korea). These techniques are convenient, fast and relatively simple for in vitro measuring the deformability and aggregation properties of RBC in blood samples. The essence of laser diffractometry is in obtaining and subsequent analysis of the obtained diffraction pattern from a highly diluted suspension of RBCs at rest and shear flow. Laser aggregometry technique allows to register the kinetics of the spontaneous aggregation (time dependence of light intensity forward scattered from a sample of whole blood at rest) and shear-induced disaggregation (shear stress dependence of light intensity backscattered from a sample of whole blood under shear flow) of RBCs for obtaining the characteristic time of aggregates formation (aggregation rate), as well as hydrodynamic strength of RBC aggregates.
All measurements were performed with human blood drawn from practically healthy volunteers. The blood samples were incubated with suspensions of iron oxide nanoparticles in phosphate-buffered saline solution in concentrations 33, 100 and 1000 µg/ml during 45 minutes. The porphyrin functionalized (Fe2O3-POR) as well as none functionalized (Fe2O3) nanoparticles were tested. We investigated blood samples from 7 volunteers. All blood samples were stabilized with EDTA to prevent blood clotting. The measurements were performed within two hours after blood sampling.
We found that 45 minutes-long incubation of RBCs with the porphyrin functionalized and non-functionalized Fe2O3 particles results in significant alterations of the aggregation kinetics and negligible changes in deformability properties of RBCs. The ability of RBC to aggregate is further impaired with increasing the nanoparticle concentration. It was shown, that characteristic time of the aggregates formation increases by 13 ± 4 %, 80 ± 11% and 115 ± 19% in the cases of 33 µg/ml, 100 µg/ml and 1000 µg/ml concentrations of Fe2O3-POR particles accordingly in comparison with the control group (without nanoparticles, pure blood). Similar results for the non-functionalized particles Fe2O3 are 5 ± 3%, 19 ± 8%, 159 ± 18%. The amplitude of the aggregation decreases by 3 ± 2%, 11 ± 8%, 23 ± 11% for the Fe2O3-POR particles and 2 ± 1%, 7 ± 4%, 30 ± 14% for the Fe2O3 particles in the cases of 33 µg/ml, 100 µg/ml and 1000 µg/ml concentrations respectively. The alterations in the aggregation are seen to be more significant for the higher nanoparticle concentrations and more pronounced for non-functionalized particles. The hydrodynamic strength was reduced by 15-42% depending on the type and concentrations of the particles.
Basing on these results one can conclude that the Fe2O3 particles can be administrated into blood in ambient conditions at low concentrations (33 µg/ml), without significant complicating the blood’s rheological conditions. However, controlling the RBCs microrheological properties is necessary during treatment. Further measurements are needed to estimate the effect of the nanoparticles at in vivo administration into blood.
The work was supported by the RFBR grant № 16-32-50128.
Dr. Andrei Egorovich Lugovtsov
International Laser Center of M.V. Lomonosov Moscow State University, Ph.D., reseacher
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