Key Laboratory of Surface and Interface Chemistry of Jilin Province, College of Chemistry, Jilin University, Changchun 130012, PR China.
Langmuir. 2010 Jan 19;26(2):1024-8. doi: 10.1021/la9041452.
A cooperative dual-responsive polypeptide surface switching between superhydrophilic and superhydrophobic states is presented. This macroscopic phenomenon of surface originates from the combination of the cooperative unfolding/aggregation of the poly-L-lysine (PLL) immobilized on the substrate with micro/nanocomposite structure in response to pH and temperature. At pH lower than the pK(a) of PLL (approximately 11.0), PLL mainly adopts a random coil conformation, which corresponds to the superhydrophilic state on the rough surface substrate. Raising the pH to higher than the pK(a) allows the appearance of alpha-helix conformation, which also corresponds to the hydrophilic state. However, heating up the surface at pH higher than the pK(a) destabilizes the alpha-helix conformation and induces the formation of aggregated beta-sheet structures, which represents the superhydrophobic state. Lowering the pH and temperature simultaneously switches a reversible conversion from superhydrophobic to superhydrophilic states. In the switching process, the hydrophobicity and hydrophilicity can be "memorized" due to the cooperative pH and temperature stimuli-induced unfolding/aggregation behaviors of PLL. This provides a new exciting prospect for understanding surface properties of polypeptides and the design of smart material surfaces with potential applications in nanodevices, bioseparation, and biosensors.
提出了一种协同双响应多肽表面，可在超亲水和超疏水状态之间切换。这种宏观表面现象源于与 pH 和温度响应的固载在基底上的聚-L-赖氨酸（PLL）的协同展开/聚集与微/纳复合结构的结合。在 pH 低于 PLL 的 pK(a)（约 11.0）时，PLL 主要采用无规卷曲构象，对应于粗糙表面基底上的超亲水状态。将 pH 升高到高于 pK(a) 允许出现 α-螺旋构象，这也对应于亲水状态。然而，在 pH 高于 pK(a) 的表面加热会破坏 α-螺旋构象并诱导形成聚集的 β-折叠结构，代表超疏水状态。同时降低 pH 和温度可将超疏水到超亲水状态的可逆转换。在转换过程中，由于 PLL 的协同 pH 和温度刺激诱导的展开/聚集行为，可以“记忆”疏水性和亲水性。这为理解多肽表面性质和设计具有纳米器件、生物分离和生物传感器应用潜力的智能材料表面提供了一个新的令人兴奋的前景。
