Kriwet B, Walter E, Kissel T
Department of Pharmaceutics and Biopharmacy Philipps-University Marburg, Ketzerbach 63, D-35032 Marburg, Germany.
J Control Release. 1998 Dec 4;56(1-3):149-58. doi: 10.1016/s0168-3659(98)00078-9.
Bioadhesive latices of water-swollen poly(acrylic acid) nano-and microparticles were synthesized using an inverse (W/O) emulsion polymerization method. They are stabilized by a co-emulsifier system consisting of SpanTM 80 and TweenTM 80 dispersed in aliphatic hydrocarbons. The initial polymerization medium contains emulsion droplets and inverse micelles which solubilize a part of the monomer solution. The polymerization is initiated by free radicals, and particle dispersions with a narrow size distribution are obtained. The particle size is dependent on the type of radical initiator used. With water-soluble initiators, for example ammonium persulfate, microparticles were obtained in the size range of 1 to 10 micrometer indicating that these microparticles originate from the emulsion droplets since the droplet sizes of the W/O emulsion show similar distribution. When lipophilic radical initiators, such as azobis-isobutyronitrile, are used, almost exclusively nanoparticles are generated with diameters in the range of 80 to 150 nm, due to the limited solubility of oligomeric poly(acrylic acid) chains in the lipophilic continuous phase. These poly(acrylic acid) micro- and nanoparticles yielded excellent bioadhesive properties in an in-vitro assay and may, therefore, be suitable for the encapsulation of peptides and other hydrophilic drugs.
采用反相（W/O）乳液聚合法合成了水溶胀性聚丙烯酸纳米颗粒和微米颗粒的生物黏附性胶乳。它们由分散在脂肪烃中的SpanTM 80和TweenTM 80组成的助乳化剂体系稳定。初始聚合介质包含乳液滴和反胶束，反胶束可溶解部分单体溶液。聚合反应由自由基引发，得到粒径分布窄的颗粒分散体。粒径取决于所用自由基引发剂的类型。使用水溶性引发剂，如过硫酸铵时，可获得粒径在1至10微米范围内的微米颗粒，这表明这些微米颗粒源自乳液滴，因为W/O乳液的液滴尺寸显示出相似的分布。当使用亲脂性自由基引发剂，如偶氮二异丁腈时，由于低聚聚丙烯酸链在亲脂性连续相中的溶解度有限，几乎只生成直径在80至150纳米范围内的纳米颗粒。这些聚丙烯酸微米颗粒和纳米颗粒在体外试验中表现出优异的生物黏附性能，因此可能适用于肽和其他亲水性药物的包封。
