Raman Spectroscopic Study of TiO2 Nanoparticles' Effects on the Hemoglobin State in Individual Red Blood Cells

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.

Fluorescence imaging of stained red blood cells with simultaneous resonance Raman photostability analysis

Simultaneous fluorescence and resonance Raman imaging of R6G-stained red blood cells with optimal laser power.

Three-dimensional mid-infrared tomographic imaging of endogenous and exogenous molecules in a single intact cell with subcellular resolution

Microscopy in the mid-infrared spectral range provides detailed chemical information on a sample at moderate spatial resolution and is being used increasingly in the characterization of biological entities as challenging as single cells. However, a conventional cellular 2D imaging measurement is limited in its ability to associate specific compositional information to subcellular structures because of the interference from the complex topography of the sample. Herein we provide a method and protocols that overcome this challenge in which tilt-series infrared tomography is used with a standard benchtop infrared microscope. This approach gives access to the quantitative 3D distribution of molecular components based on the intrinsic contrast provided by the sample. We demonstrate the method by quantifying the distribution of an exogenous metal carbonyl complex throughout the cell and by reporting changes in its coordination sphere in different locations in the cell.

Surface-enhanced Raman scattering of whole human blood, blood plasma, and red blood cells: cellular processes and bioanalytical sensing

SERS spectra of whole human blood, blood plasma, and red blood cells on Au nanoparticle SiO(2) substrates excited at 785 nm have been observed. For the sample preparation procedure employed here, the SERS spectrum of whole blood arises from the blood plasma component only. This is in contrast to the normal Raman spectrum of whole blood excited at 785 nm and open to ambient air, which is exclusively due to the scattering of oxyhemoglobin. The SERS spectrum of whole blood shows a storage time dependence that is not evident in the non-SERS Raman spectrum of whole blood. Hypoxanthine, a product of purine degradation, dominates the SERS spectrum of blood after ~10-20 h of storage at 8 °C. The corresponding SERS spectrum of plasma isolated from the stored blood shows the same temporal release of hypoxanthine. Thus, blood cellular components (red blood cells, white blood cells, and/or platelets) are releasing hypoxanthine into the plasma over this time interval. The SERS spectrum of red blood cells (RBCs) excited at 785 nm is reported for the first time and exhibits well-known heme group marker bands as well as other bands that may be attributed to cell membrane components or protein denaturation contributions. SERS, as well as normal Raman spectra, of oxy- and met-RBCs are reported and compared. These SERS results can have significant impact in the area of clinical diagnostics, blood supply management, and forensics.