Differences in light scattering properties of a tumorigenic and a non-tumorigenic model for tissue were demonstrated using a variety of light scattering techniques, the majority of which are in vivo compatible. In addition to determining that light scattering differences exist, models for the microarchitectural changes responsible for the light scattering differences were developed.

A rapid tool for the characterization of submicron particles is light spectroscopy. Rayleigh-Debye-Gans and Mie theories provide light scattering solutions that can be evaluated within the time constants required for continuous real time monitoring applications, as in characterization of biological particles. A multiwavelength assessment of Rayleigh-Debye-Gans theory for spheres was conducted over the UV-Vis wavelength range where strict adherence to the limits of the theory at a single wavelength could not be met. Reported corrections to the refractive indices were developed to extend the range of application of the Rayleigh-Debye-Gans approximation. The results of this study show that there is considerable disagreement between Rayleigh-Debye-Gans and Mie theory across the UV-Vis spectrum.

Multiwavelength UV-visible transmission spectrophotometry is a useful tool for the examination of micron-size particle suspensions in the context of particle size and chemical composition. This paper reports the reliability of this method to characterize the spectra of purified red blood cells both in their physiological state and with modified hemoglobin content. Previous studies have suggested the contribution of hypochromism on the particle spectra caused by the close electronic interaction of the encapsulated chromophores. Our research shows, however, that this perceived hypochromism can be accounted for by considering two important issues: the acceptance angle of the instrument and the combined scattering and absorption effect of light on the particles. In order to establish these ideas, spectral analysis was performed on purified and modified red cells where the latter was accomplished with a modified hypotonic shock protocol that altered the hemoglobin concentration within the cells. Moreover, the Mie theory was used to successfully simulate the spectral features and trends of the red cells. With this combination of experimental and theoretical exploration, definition of hypochromism has been extended to two subcategories.

Rayleigh-Debye-Gans and Mie theory were previously shown to disagree for spherical particles under ideal conditions4. A Hybrid model for spheres was developed by the authors combining Mie theory and Rayleigh- Debye-Gans. The hybrid model was tested against Mie and Rayleigh- Debye-Gans for different refractive indices and diameter sizes across the UV-Vis spectrum. The results of this study show that the hybrid model represents a considerable improvement over Rayleigh-Debye-Gans for submicron particles and is computationally more effective compared to Mie model. The development of the spherical hybrid model establishes a platform for the analysis of non-spherical particles.

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