Fischell Department of Bioengineering, University of Maryland, Room 3102 A. James Clark Hall, 8278 Paint Branch Dr. and College Park, MD 20742, USA.
Nanoscale. 2019 Oct 3;11(38):17904-17912. doi: 10.1039/c9nr04624k.
A tunable protease responsive nanoparticle hydrogel (PRNH) that demonstrates large non-iridescent color changes due to a degradation-directed assembly of nanoparticles is reported. Structurally colored composites are fabricated with silica particles, 4-arm poly(ethylene glycol) norbornene (4PEGN), and a proteolytically degradable peptide. When placed in a protease solution, the peptide crosslinks degrade causing electrostatic binding and adsorption of the polymer to the particle surface which leads to the assembly of particles into compact amorphous arrays with structural color. The particle surface charge and size is investigated to probe their effect on the assembly mechanism. Interestingly, only PRNHs with highly negative particle surface charge exhibit color changes after degradation. Ultra-small angle X-ray scattering revealed that the particles become coated in polymer after degradation, producing a material with less order compared to the initial state. Altering the particle diameter modulates the composites' color, and all sizes investigated (178-297 nm) undergo the degradation-directed assembly. Varying the amount of 4PEGN adjusts the swollen PRNH color and has no effect on the degradation-directed assembly. Taken together, the effects of surface charge, particle size, and polymer concentration allow for the formulation of new design rules for fabricating tunable PRNHs that display vivid changes in structural color upon degradation.
一种可调谐的蛋白酶响应纳米颗粒水凝胶（PRNH）被报道，由于纳米颗粒的降解导向组装，该水凝胶表现出大的非虹彩颜色变化。结构色复合材料是用二氧化硅颗粒、四臂聚乙二醇降冰片烯（4PEGN）和可酶降解的肽制备的。当置于蛋白酶溶液中时，肽交联降解导致聚合物与颗粒表面的静电结合和吸附，从而导致颗粒组装成具有结构色的紧密无定形阵列。研究了颗粒表面电荷和粒径以探究它们对组装机制的影响。有趣的是，只有具有高负颗粒表面电荷的 PRNH 在降解后才表现出颜色变化。小角 X 射线散射表明，颗粒在降解后被聚合物包裹，与初始状态相比，产物的有序性降低。改变颗粒直径可以调节复合材料的颜色，并且所有研究的尺寸（178-297nm）都经历了降解导向的组装。改变 4PEGN 的量可以调节溶胀的 PRNH 颜色，但对降解导向的组装没有影响。总之，表面电荷、颗粒尺寸和聚合物浓度的影响允许制定新的设计规则，用于制备在降解时显示结构颜色明显变化的可调谐 PRNH。
