INFLUENCE OF DEXTRAN MOLECULAR-WEIGHT ON CAPTURE IN AND RELEASE FROM DECYLAMINE CARBOXYMETHYLCELLULOSE CAPSULES

A series of dextran molecular weight markers were encapsulated in decy lamine carboxymethylcellulose microcapsules to serve as probes of caps ule retentivity. The capsules were prepared by allowing microdrops of aqueous sodium carboxymethylcellulose to fall into aqueous decylamine acetate solution. Salt exchange reaction at the droplet pseudointerfac e resulted in self-assembling films which essentially instantaneously enclosed the droplets. Concentrations of anionic polymer were varied i n the range from 1-3%. Chromophore-bearing dextrans were incorporated into these capsules by blending the dextrans with the carboxymethylcel lulose prior to the encapsulation step. Four dextrans of differing (li ght scattering) molecular weights were used: 2 x 10(6), 6 x 10(5), 7 x 10(4), and 1.9 x 10(4) amu. The mass balance of dextran retained in t he capsules, released on washing the capsules or which escaped encapsu lation was determined spectrophotometrically. To measure total dextran in a population of washed capsules, the capsules were lysed in a 0.3 M solution of sodium chloride. To monitor dextran release, washed caps ules were suspended in water and dextran concentration in the supernat ant was measured. Encapsulation efficiency exceeded 80% for high molec ular weight dextran but was lower with the smaller dextrans.