Hydrogel-based depots are of growing interest for release of biopharmaceuticals; however, a priori selection of hydrogel compositions that will retain proteins of interest and provide desired release profiles remains elusive. Toward addressing this, in this work, we have established a new tool for the facile assessment of protein release from hydrogels and applied it to evaluate the effectiveness of mesh size estimations on predicting protein retention or release. Poly(ethylene glycol) (PEG)-based hydrogel depots were formed by photoinitiated step growth polymerization of four-arm PEG functionalized with norbornene (PEG-norbornene, 4% w/w to 20% w/w, M_n ∼ 5 to 20 kDa) and different dithiol cross-linkers (PEG M_n ∼ 1.5 kDa or enzymatically degradable peptide), creating well-defined, robust materials with a range of mesh sizes estimated with Flory–Rehner or rubber elasticity theory (∼5 to 15 nm). A cocktail of different model proteins was released from compositions of interest, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used to facilely and quantitatively analyze temporal release profiles. Mesh size was predictive of retention of relatively large proteins and release of relatively small proteins. Proteins with diameters comparable to the mesh size, which is often the case for growth factors, were released by hindered diffusion and required experimental assessment of retention and release. With this knowledge, hydrogels were designed for the controlled release of a therapeutically relevant growth factor, PDGF-BB.

中文翻译：

---

调整和预测逐步生长水凝胶的筛孔尺寸和蛋白质释放

基于水凝胶的储库对释放生物药物的兴趣日益增长。然而，将保留感兴趣的蛋白质并提供所需的释放曲线的水凝胶组合物的先验选择仍然难以实现。为了解决这个问题，在这项工作中，我们建立了一个新的工具，可以轻松评估水凝胶中的蛋白质释放，并将其用于评估筛孔尺寸估计对预测蛋白质保留或释放的有效性。通过以降冰片烯官能化的四臂PEG（PEG-降冰片烯，4％w / w至20％w / w，M _n〜5至20 kDa）和不同的二硫醇交联剂（PEG M _n约1.5 kDa或可酶降解的肽），可以创建定义明确，坚固的材料，其网眼尺寸范围由Flory-Rehner或橡胶弹性理论估算（约5至15 nm）。从目标组合物中释放出不同模型蛋白质的混合物，十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）用于方便和定量地分析时间释放曲线。网孔大小预示着较大蛋白质的保留和相对较小蛋白质的释放。直径可与筛孔大小相媲美的蛋白质（通常是生长因子）通过阻碍扩散的方式释放出来，并需要对保留和释放进行实验评估。有了这些知识，就可以设计水凝胶来控制释放治疗相关的生长因子PDGF-BB。