Preparation and characterization of cellulose microspheres Katrin Thu ¨ mmler • Steffen Fischer • Alexander Feldner • Viktoria Weber • Marion Ettenauer • Fritz Loth • Dieter Falkenhagen Received: 20 August 2010 / Accepted: 2 November 2010 / Published online: 11 November 2010 Ó Springer Science+Business Media B.V. 2010 Abstract The aim of this work was to synthesize and characterize cellulose microspheres with a particle size below 5 lm and narrow size distribution. After activation and functionalization with antibodies, these particles shall be applied as adsorbents in suspension- based extracorporeal blood purification systems, such as the Microspheres-Based Detoxification System. In the frame of this work such microspheres were developed and synthesized with reproducible proper- ties. Besides using well-established methods for char- acterization of this kind of bead cellulose, additional procedures for the examination of its properties were developed and applied. Keywords Bead cellulose  Cellulose microspheres  Extracorporeal blood purification  Particle size distribution  Scanning electron microscopy  Sedimentation behavior  Analytical centrifugation Introduction Cellulosic polymers are widely applied in medicine and generally regarded as biocompatible. Bead cellulose was first described as cellulose pellets in US-patent 2543928 [O‘Neill and Reichardt 1951]. It has wide ranging applications, e.g. as separation medium, carrier system and as adsorbent in extracor- poral blood purification (e.g. Pes ˇka et al. 1976; Kuga 1980; Kaster et al. 1993; Wolf and Horsch 1991; Wolf et al. 1996; de Oliveira and Glasser 1996a, b; Volkert et al. 2009). A well known method for preparing bead cellulose on the basis of cellulose acetate with an average degree of substitution between 1.5 and 2.7 was applied (Wagenknecht et al. 1996). This technology is characterized in that the solution of cellulose acetate is free of halogenated hydrocarbons. For this emulsion process of bead cellulose preparation, cellulose-2.5-acetate is dissolved in methyl acetate or ethyl acetate or in a mixture of ethyl acetate and methanol, that means in a solvent non-miscible or only partially miscible with water. This solution is vigorously mixed with an aqueous medium contain- ing a surface active substance (tenside), a protective colloid and a certain amount of salt in order to form fine droplets of cellulose acetate. The following steps are evaporation of the solvents, separation of the fine acetate particles by centrifugation and washing of the cellulose acetate beads with water. For forming cellulose beads a final deacetylation step is necessary. K. Thu ¨mmler (&)  S. Fischer  A. Feldner Institute of plant and wood chemistry, Technische Universita ¨t Dresden, Pienner Str. 19, 01737 Tharandt, Germany e-mail: katrin.thuemmler@forst.tu-dresden.de V. Weber  M. Ettenauer  F. Loth  D. Falkenhagen Center for Biomedical Technology, Danube University Krems, Dr.-Karl-Dorrek-Straße 30, 3500 Krems, Austria e-mail: viktoria.weber@donau-uni.ac.at 123 Cellulose (2011) 18:135–142 DOI 10.1007/s10570-010-9465-z