Testing of Dynamic Light Scattering for Characterization of Hyaluronan and Human Liquid Vitreous

The current work was mainly dedicated to the practical realization of an idea applying DLS optical method for the characterization of thin layers of hyaluronan and tear film fluids. Being non-invasive, rapid and precise DLS techniques can be eomplyed for the investigation of not only non-organic materials, but also for the analysis of biological tissues in vivo. That has been confirmed during numerous clinical studies worldwide.

The aim of this work was to revise the exiting knowledge about the hyalurononic acid and tear film fluid applying DLS optical method, in order to make the preliminary preparations for the further opthalmologica research on this topic. The next steps are going to be in vivo tests of the endothelials cells of th post corneal eye region for the detection and study molecules of hyaluronan at the eye segment. Broadening knowledge on this issue might contribute to the invention of a new methodology for prevention and treating glaucoma diesease. That was the main motivation of the studies.

During this project a special set up was assembled and tested. our main goal was to construct the experimental system to perform DLS test in the homodyne reigme. In order to diminish the amount of optical components employed in the experiment mono-mode fibers were used. Having specific characteristics and features, optical fiber components require non-trivial solutions for integration them into the DLS experiments. Using optical wave-guides to supply the existing frequency of the laser light to the measuring cell and to collect the scattered signal afterward dictates a particular scattering geometry. There are limitation of adding a local oscillator field to the main laser beam at the detection stage to realize the heterodyne regime conditions. Thus only homodyne regime conditions could be fulfilled nowadays. But nevertheless, applying optical fibers in DLS experiment do already offer unchallenged advantages and have big potential to be extensively used in future.

During this project biological samples of hyaluronan and tear film fluid were tested, as well as the solutions of monodispers silica particles with know parameters-particle size. Studying the reference silica particles samples the theoretical values for the viscosity of the solutions with correction for the exact temperature measurements were confirmed. Correlation functions of the scattered light registerd and processed later on. Analysis of the autocorrlation funciton in terms of the particle size distribution was done by numerically fitting the data with calculations based on assumed distributions. IN case of truly monodisperse particle samples single exponential decay diagrams were registered to which fitting a calculated particle size distribution was relatively straightforward.