Raman Spectroscopic Study of TiO Nanoparticles' Effects on the Hemoglobin State in Individual Red Blood Cells.

Titanium dioxide (TiO) is considered to be a nontoxic material and is widely used in a number of everyday products, such as sunscreen. TiO nanoparticles (NP) are also considered as prospective agents for photodynamic therapy and drug delivery. These applications require an understanding of the potential effects of TiO on the blood system and its components upon administration. In the presented work, we analyze the interaction of TiO nanoparticles of different crystal phases (anatase and rutile) with individual rat Red Blood Cells (RBC) and the TiO 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 TiO NP on the RBC. No penetration of the NP inside RBC was observed; however, both kinds of TiO 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 TiO photothermal effect on Hb under Raman laser excitation, are suggested. The possible influence on the safety of TiO use in advanced medical application, especially on the safety and efficiency of photothermal therapy, is discussed.