Preparation and characterization of NaCS–CMC/PDMDAAC capsules

Abstract: A novel capsule system composed of sodium cellulose sulfate (NaCS), carboxymethyl cellulose (CMC) and poly[dimethyl(diallyl)ammonium chloride] (PDMDAAC) was prepared for improving the properties of NaCS/PDMDAAC capsules. The process parameters, such as CMC concentration (0, 2, 4, 6 and 8g/L), NaCS concentration (20, 25, 30, 35 and 40g/L), PDMDAAC concentration (20, 30, 40, 50, 60, 70 and 80g/L), reaction time and temperature were investigated to understand their effects on the diameter, membrane thickness and mechanical strength of capsules. The optimum operation conditions for preparing NaCS–CMC/PDMDAAC capsules were determined as 6–8g/L CMC, 35–40g/L NaCS, 60g/L PDMDAAC and polymerization for 30–40min. Diffusion of substances with low molecular weight into capsules was investigated, and diffusion coefficients were calculated according to the developed model. The yeast of Candida krusei was chosen as representative cell to evaluate the effects of different cell loading on capsule mechanical strength. Meanwhile the encapsulated osmophilic C. krusei cells were cultured in 250mL shaking flasks for 72h to determine the cell leaking properties in short and long term. [Copyright &y& Elsevier]