Faculty of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands.
Faculty of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
J Mater Chem B. 2024 Nov 13;12(44):11389-11401. doi: 10.1039/d4tb01320d.
Collective behavior has become a recent topic of investigation in systems chemistry. In pursuing this phenomenon, we present polymersome stomatocytes loaded with the enzyme urease, which show basic stigmergy-based communication and are capable of signal production, reception, and response by clustering with surface complementary binding partners. The collective behavior is transient and based on the widely known pH-sensitive non-covalent interactions between nitrilotriacetic acid (NTA) and histidine (His) moieties attached to the surface of urease-loaded and empty stomacytes, respectively. Upon the addition of the substrate urea, the urease stomatocytes are able to increase the environmental pH, allowing the NTA units to interact with the surface histidines on the complementary species, triggering the formation of transient clusters. The stomatocytes display a maximum clustering interaction at a pH between 6.3 and 7.3, and interparticle repulsive behavior outside this range. This leads to oscillating behavior, as the aggregates disassemble when the pH increases due to high local urease activity. After bulk pH conditions are restored, clustering can take place again. Within the detectable region of dynamic light scattering, individual stomatocytes can aggregate to agglomerates with 10 times their volume. Understanding and designing population behavior of active colloids can facilitate the execution of cooperative tasks, which are not feasible for individual colloids.
集体行为已成为系统化学研究的一个新课题。在研究这一现象时，我们提出了负载酶脲酶的聚合物囊泡，其表现出基本的基于痕迹的通信，并能够通过与表面互补结合伙伴聚类来进行信号的产生、接收和响应。这种集体行为是短暂的，基于广泛存在的 pH 敏感非共价相互作用，分别存在于负载脲酶和空囊泡表面的氮川三乙酸 (NTA) 和组氨酸 (His) 部分之间。当加入基质尿素时，脲酶囊泡能够增加环境 pH 值，允许 NTA 单元与互补物种表面的组氨酸相互作用，触发瞬态聚类的形成。囊泡在 pH 值为 6.3 到 7.3 之间显示出最大的聚类相互作用，在这个范围之外则表现出粒子间的排斥行为。这导致了振荡行为，因为由于局部脲酶活性高，当 pH 值增加时，聚集物会分解。在恢复批量 pH 条件后，聚类可以再次发生。在动态光散射的可检测区域内，单个囊泡可以聚集到体积增加 10 倍的聚集体。理解和设计活性胶体的群体行为可以促进合作任务的执行，而单个胶体是无法完成这些任务的。
