Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371.
Small. 2015 Feb 11;11(6):740-8. doi: 10.1002/smll.201401343. Epub 2014 Sep 29.
The ability to shape-shift in response to a stimulus increases an organism's survivability in nature. Similarly, man-made dynamic and responsive "smart" microtechnology is crucial for the advancement of human technology. Here, 10-30 μm shape-changing 3D BSA protein hydrogel microstructures are fabricated with dynamic, quantitative, directional, and angle-resolved bending via two-photon photolithography. The controlled directional responsiveness is achieved by spatially controlling the cross-linking density of BSA at a nanometer lengthscale. Atomic force microscopy measurements of Young's moduli of structures indicate that increasing the laser writing distance at the z-axis from 100-500 nm decreases the modulus of the structure. Hence, through nanoscale modulation of the laser writing z-layer distance at the nanoscale, control over the cross-linking density is possible, allowing for the swelling extent of the microstructures to be quantified and controlled with high precision. This method of segmented moduli is applied within a single microstructure for the design of shape-shifting microstructures that exhibit stimulus-induced chirality, as well as for the fabrication of a free-standing 3D microtrap which is able to open and close in response to a pH change.
生物体能够根据刺激改变形状，从而提高其在自然界中的生存能力。同样，人造的动态响应“智能”微技术对于人类技术的进步至关重要。在这里，通过双光子光刻技术制造了具有 10-30μm 变形能力的 3D BSA 蛋白质水凝胶微结构，该微结构具有动态、定量、定向和角度分辨弯曲的特性。通过在纳米尺度上控制 BSA 的交联密度来实现受控的定向响应。对结构杨氏模量的原子力显微镜测量表明，增加 z 轴上激光写入距离（从 100-500nm）会降低结构的模量。因此，通过在纳米尺度上对激光写入 z 层距离进行纳米级调制，可以控制交联密度，从而可以精确地量化和控制微结构的溶胀程度。这种分段模量的方法应用于单个微结构中，用于设计具有刺激诱导手性的形状变形微结构，以及制造能够响应 pH 值变化而打开和关闭的自由站立 3D 微阱。
