Spinelli Frances J, Kiick Kristi L, Furst Eric M
Department of Chemical Engineering, University of Delaware, 150 Academy Street, Colburn Laboratory, Newark, DE 19716, USA.
Biomaterials. 2008 Apr;29(10):1299-306. doi: 10.1016/j.biomaterials.2007.11.045. Epub 2007 Dec 31.
The extensive use of the glycosaminoglycan (GAG) heparin in the design of emerging biomaterials has made the physical characterization of this heterogeneous biomacromolecule increasingly important. In this work, heparin solutions are characterized via dynamic light scattering to investigate heparin's self-association, since this behavior was recently hypothesized to play a role in the gelation of heparin-functionalized polymer hydrogels. Samples of either low molecular weight heparin or high molecular weight heparin were filtered using membranes with 100, 220, or 450 nm average pore sizes. The 100 and 220 nm filters produce a single population of monomers with a diameter range of 3-10nm in the intensity-weighted size distribution. However, the 450 nm filters reveal a second population of associated heparin. Increasing the solution concentration of high molecular weight heparin (HMWH) from 2.5 to 10 wt% causes the magnitude of the smaller population to decrease, while the diameter of the larger associated species approximately doubles. HMWH from different manufacturers displays varying degrees of association. Therefore, weaker associating HMWH can potentially be identified to control heparin self-interactions. Finally, fractionated, N-deacetylated low molecular weight heparin (LMWH) is compared to unmodified LMWH. The chemically modified heparin exhibits a heightened degree of association, suggesting an enhanced self-interaction. The increased negative charge of LMWH in the fractionated sample likely enhances polyelectrolyte interactions proposed to drive the association of these similarly charged polysaccharides. A more detailed understanding of heparin-heparin interactions will assist in the design of new scaffold materials with controlled release profiles, in the clinical use of heparin as an anticoagulant, and in investigations of interactions of other like-charged biomacromolecules.
糖胺聚糖（GAG）肝素在新型生物材料设计中的广泛应用，使得对这种异质生物大分子进行物理表征变得越发重要。在本研究中，通过动态光散射对肝素溶液进行表征，以研究肝素的自缔合现象，因为最近有人推测这种行为在肝素功能化聚合物水凝胶的凝胶化过程中发挥作用。使用平均孔径为100、220或450 nm的膜对低分子量肝素或高分子量肝素样品进行过滤。在强度加权尺寸分布中，100和220 nm的滤膜产生直径范围为3 - 10nm的单一单体群体。然而，450 nm的滤膜显示出第二种缔合肝素群体。将高分子量肝素（HMWH）的溶液浓度从2.5 wt%提高到10 wt%，会使较小群体的数量减少，而较大缔合物种的直径大约翻倍。不同制造商的HMWH表现出不同程度的缔合。因此，有可能识别出缔合较弱的HMWH来控制肝素的自相互作用。最后，将分级分离的N - 脱乙酰化低分子量肝素（LMWH）与未修饰的LMWH进行比较。化学修饰的肝素表现出更高程度的缔合，表明其自相互作用增强。分级分离样品中LMWH增加的负电荷可能增强了聚电解质相互作用，这种相互作用被认为驱动了这些带相同电荷多糖的缔合。对肝素 - 肝素相互作用的更详细了解将有助于设计具有可控释放特性的新型支架材料、肝素作为抗凝剂的临床应用以及其他带相同电荷生物大分子相互作用的研究。
