Cegnar Mateja, Miklavžin Ana, Kerč Janez
Acta Chim Slov. 2011 Jun;58(2):241-50.
Polyelectrolyte complexes (PEC) consisting of an alginate core entrapping the protein ovalbumin and the chitosan coating were prepared by the self-assembly of oppositely charged polyelectrolytes. The PEC were prepared at pH 4.0 and consisted of alginate, ovalbumin and chitosan in a concentration of 0.5, 0.5 and 0.05 mg/ml, respectively, having a particle size of around 300nm, a zeta potential of -44 mV and a protein association efficiency of 80%. The release of ovalbumin from PEC was mostly dependant on the pH of release medium and the presence of strong electrolytes contributed to higher release. Approximately 90% of the ovalbumin was released in a phosphate buffer media, pH 7.4. The release was lower in media with pH 4.0, reaching the value of app. 40% and 60% of ovalbumin released in water (pH 4.0) and NaCl solution (0.9% w/v, pH 4.0), respectively. In an acidic saline solution, pH 3.0, there was only 5% of ovalbumin release, however, increasing the pH to 6.8, approximately 70% of ovalbumin immediately released from the PEC. The PEC were freeze-dried aided by various excipients. Their efficiency on the redispersibility of the freeze-dried product was evaluated according to the mean particle diameter, polydispersity, average scattering intensity (particle concentration) and visual appearance of the PEC (Tyndal effect). In the presence of trehalose and mannitol, the aggregation and integrity of the PEC were prevented, yielding properties similar to the PEC dispersion before lyophilisation. The surface hydrophobicity of the ovalbumin either free or formulated in the nanocomplexes was determined by the bis-ANS fluorescence intensity, indicating a higher surface hydrophobicity for the PEC. The mild formulation conditions, nanometre-sized particles, high protein association efficiency, pH-dependant release, and modified surface properties are promising factors towards the development of an oral delivery system for protein made by the self-assembly of oppositely charged polyelectrolytes.
通过带相反电荷的聚电解质自组装制备了聚电解质复合物（PEC），其由包裹着蛋白质卵清蛋白的藻酸盐核心和壳聚糖涂层组成。PEC在pH 4.0条件下制备，分别由浓度为0.5、0.5和0.05mg/ml的藻酸盐、卵清蛋白和壳聚糖组成，粒径约为300nm，ζ电位为-44mV，蛋白质结合效率为80%。卵清蛋白从PEC中的释放主要取决于释放介质的pH值，强电解质的存在会导致更高的释放率。在pH 7.4的磷酸盐缓冲介质中，约90%的卵清蛋白被释放。在pH 4.0的介质中释放率较低，在水（pH 4.0）和NaCl溶液（0.9% w/v，pH 4.0）中卵清蛋白的释放率分别达到约40%和60%。在pH 3.0的酸性盐溶液中，只有5%的卵清蛋白释放，然而，将pH值提高到6.8时，约70%的卵清蛋白立即从PEC中释放出来。PEC在各种赋形剂的辅助下进行冷冻干燥。根据PEC的平均粒径、多分散性、平均散射强度（颗粒浓度）和外观（廷德尔效应）评估它们对冷冻干燥产品再分散性的影响。在海藻糖和甘露醇存在的情况下，PEC的聚集和完整性得到了防止，产生了与冻干前PEC分散体相似的性质。通过双-ANS荧光强度测定了游离或纳米复合物中配制的卵清蛋白的表面疏水性，表明PEC具有更高的表面疏水性。温和的制剂条件、纳米级颗粒、高蛋白结合效率、pH依赖性释放和改性表面性质是通过带相反电荷的聚电解质自组装开发蛋白质口服给药系统的有前景的因素。
