Chadha H, DeLuca P P
University of Kentucky, College of Pharmacy, Faculty of Pharmaceutical Sciences, Lexington 40536-0082, USA.
Pharm Dev Technol. 1998 Nov;3(4):597-606. doi: 10.3109/10837459809028644.
The polypeptide, poly-l-tyrosine (PTYR) was incorporated into hydroxyethyl starch (HES) microspheres to modify the surface hydrophobicity in order to allow subsequent radioiodination and assessment of uptake into the intestinal mucosa following oral administration. The HES microspheres were prepared by a crosslinking polymerization process and characterized for particle size, peptide content and surface morphology. The hydrophobicity of the characterized microspheres was assessed by two techniques-water uptake (swelling) of the microspheres and contact angle measurement using the sessile drop method. Spherical microspheres containing PTYR were prepared with a greater than 80% loading efficiency in the 1-10 microns size range. The surface morphology suggested localization of the PTYR at the surface proportionate to the loading. The percent water uptake of the blank HES microspheres was 87%, whereas that of the 5, 10 and 20% PTYR/HES microspheres was 84%, 61% and 55%, respectively. HES/PTYR was polymerized as films to facilitate contact angle measurement. A monotonical increase in the contact angle was observed as the concentration of the PTYR was increased to 20%. Contact angle of pure HES (0% PTYR) films was 16 degrees and for the PTYR-containing films was 29 degrees for 5% PTYR, 39 degrees for 10% and 57 degrees for 20%. The hydrophobicity of the HES microsphere system could be increased by the incorporation of polytyrosine thereby paving the way to radioiodinate the microspheres and perform uptake studies in an animal model.
将多肽聚-L-酪氨酸（PTYR）掺入羟乙基淀粉（HES）微球中，以改变其表面疏水性，从而便于后续进行放射性碘化，并评估口服给药后其在肠黏膜中的摄取情况。通过交联聚合过程制备HES微球，并对其粒径、肽含量和表面形态进行表征。通过两种技术评估所表征微球的疏水性——微球的吸水率（膨胀率）以及使用静滴法测量接触角。制备出了含有PTYR的球形微球，其粒径在1 - 10微米范围内，负载效率大于80%。表面形态表明PTYR在表面的定位与负载量成比例。空白HES微球的吸水率为87%，而5%、10%和20% PTYR/HES微球的吸水率分别为84%、61%和55%。将HES/PTYR聚合成薄膜以方便测量接触角。随着PTYR浓度增加至20%，观察到接触角呈单调增加。纯HES（0% PTYR）薄膜的接触角为16度，含5% PTYR的薄膜接触角为29度，含10% PTYR的为39度，含20% PTYR的为57度。通过掺入聚酪氨酸可以提高HES微球系统的疏水性，从而为微球的放射性碘化及在动物模型中进行摄取研究铺平道路。
