Titanium dioxide (TiO2) is considered to be a nontoxic material and is widely used in a number of everyday products, such as sunscreen. TiO2 nanoparticles (NP) are also considered as prospective agents for photodynamic therapy and drug delivery. These applications require an understanding of the potential effects of TiO2 on the blood system and its components upon administration. In the presented work, we analyze the interaction of TiO2 nanoparticles of different crystal phases (anatase and rutile) with individual rat Red Blood Cells (RBC) and the TiO2 influence on the oxygenation state and functionality of RBC, estimated via analysis of Raman spectra of Hemoglobin (Hb) and their distribution along individual RBC. Raman spectral signals also allow localization of the TiO2 NP on the RBC. No penetration of the NP inside RBC was observed; however, both kinds of TiO2 NP adsorbed on the RBC membrane can affect the Hb state. Mechanisms involving the NP-membrane-Hb interaction, resulting in partial deoxygenation of Hb and TiO2 photothermal effect on Hb under Raman laser excitation, are suggested. The possible influence on the safety of TiO2 use in advanced medical application, especially on the safety and efficiency of photothermal therapy, is discussed.
Keywords: Raman mapping; Raman spectroscopy; hemoglobin; red blood cell; titanium dioxide nanoparticles.