Optical anisotropy of uniformly aligned planar surfactant lyotropic nematic doped with hemoglobin

The system under study is a nematic phase of lyotropic surfactant liquid crystal, cetylpyridinium chloride/hexanol/brine. Optical birefringence measured for well-aligned surfactant nematic (surfonematic) is weakly dependent on the light wavelength within the studied spectral region (500–700 nm) and its absolute value is about 6*10-4. Doping of the surfonematic by hemoglobin (1.5% by weight) does not affect the birefringence value, suggesting that the hemoglobin does not produce its own birefringence and does not affect the scalar orienta-tional order parameter of the surfonematic matrix. The absorption coefficients of hemoglobin in the surfonematic matrix exhibit a broad band shifted several tens of nanometres towards longer wavelengths, when compare to the spectrum of hemoglobin dissolved in water. The latter indicates that the hemoglobin residues form molecular complexes with the surfactant molecules. Weak (app.2*10-2) linear dichroism of hemoglobin at the wavelengths corresponding to light absorption by oxygen bonds gives the estimation of the orientational scalar order parameter of hemoglobin molecules in well-aligned surfonematic matrix (app. 10-2)