Lin Chien-Chi, Metters Andrew T
Department of Bioengineering, Clemson University, Clemson, South Carolina 29634.
Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634.
J Biomed Mater Res A. 2007 Dec 15;83(4):954-964. doi: 10.1002/jbm.a.31282.
Affinity hydrogels based on poly(ethylene glycol) diacrylate and a metal-ion-chelating ligand, glycidyl methacrylate-iminodiacetic acid, have been developed to systematically decrease protein release rates from hydrophilic tissue engineering scaffolds formed in situ. In the current work, tunable and sustained release of a model protein, hexa-histidine tagged green fluorescence protein (hisGFP), is accomplished by judiciously increasing ligand:protein ratio or replacing low-affinity nickel ions with high-affinity copper ions. Agreement between theoretical predictions of a reaction-diffusion model and experimental measurements confirm metal- ion-mediated sustained protein release from these affinity hydrogels is governed by equilibrium protein-ligand binding affinity (dissociation constant, Kd) as well as protein-ligand dissociation kinetics (protein debinding rate constant, k off). The former dictates the release rate in the early period of protein release while the latter determines the long-term sustained release effect. While metal-ion affinity binding has been widely used for various purposes including protein purification and surface patterning, this is the first report describing its application in systematically controlling protein release from hydrophilic PEG networks suitable for cell encapsulation. By using ligands with proper binding kinetic constants (Kd and k off), localized protein delivery can be sustained over clinically relevant timescales while maintaining a favorable environment for cell encapsulation and viability.
基于聚乙二醇二丙烯酸酯和金属离子螯合配体甲基丙烯酸缩水甘油酯-亚氨基二乙酸的亲和水凝胶已被开发出来，用于系统地降低原位形成的亲水性组织工程支架中蛋白质的释放速率。在当前的工作中，通过明智地提高配体与蛋白质的比例或用高亲和力的铜离子取代低亲和力的镍离子，实现了模型蛋白六组氨酸标记的绿色荧光蛋白（hisGFP）的可调谐和持续释放。反应扩散模型的理论预测与实验测量结果之间的一致性证实，这些亲和水凝胶中金属离子介导的蛋白质持续释放受平衡蛋白-配体结合亲和力（解离常数，Kd）以及蛋白-配体解离动力学（蛋白解离速率常数，k off）的控制。前者决定了蛋白质释放早期的释放速率，而后者决定了长期的持续释放效果。虽然金属离子亲和结合已被广泛用于包括蛋白质纯化和表面图案化在内的各种目的，但这是第一份描述其在系统控制适合细胞封装的亲水性聚乙二醇网络中蛋白质释放方面应用的报告。通过使用具有适当结合动力学常数（Kd和k off）的配体，可以在临床相关的时间尺度上维持局部蛋白质递送，同时为细胞封装和活力维持有利的环境。
