(637c) Modified Glucan Particles for Drug Delivery and Magnetic Resonance Imaging

Glucan particles are purified Saccharomyces cerevisiae (or baker’s yeast) cell walls. They typically consist of 85 % 1,3-D-glucan polymers, 2 % chitin, 1 % protein and lipids, the rest being inorganic matter and moisture. They are hollow, porous 2–5 μm microspheres. The 1,3-β-glucan outer shell provides receptor-mediated uptake by phagocytic cells expressing β-glucan receptors. They can be used as a drug carrier for the macrophage drug delivery.

In the present work, glucan particles have been isolated from Saccharomyces cerevisiae and purified. Subsequently, the release kinetics of vitamin B12 as a model drug substance from lyophilized vitamin loaded glucan particles was measured. The experiments were made at different pH values (pH = 1; 3; 5; 7,4; 9; 12) and at different temperatures (20 °C, 37 °C, 60 °C) with UV-Vis spectrometry in quartz cuvettes with magnetic stirring. The pH- and temperature-dependent diffusion coefficients of vitamin B12 across the glucan wall were calculated from the experimental results.

The composite material (Glucan-Super Paramagnetic Iron Oxide Nanoparticles, G-SPIONs) for combined drug delivery and Magnetic Resonance Imaging (MRI) was then made. The composite was prepared from pure glucan particles and superparamagnetic iron oxides nanoparticles (SPIONs). Adsorption of SPIONs on the glucan particles was based on their opposite charge (measured by the zeta-potential) achieved by suitable surface modification. The MRI imaging of whole G-SPIONs was made under dynamic flow physiological conditions in a 3D capillary network medium positioned in the MRI device.