Zhang Junning, Liu Sida, Kanokkanchana Kannasoot, Kuzina Mariia, Zhou Meijun, Du Xin, Gu Zhongze, Dong Zheqin, Levkin Pavel A
Institute of Biological and Chemical Systems-Functional Molecular Systems (IBCS-FMS), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 211189, China.
Small. 2025 Feb;21(5):e2403405. doi: 10.1002/smll.202403405. Epub 2024 Dec 17.
Two-photon lithography (TPL) enables the fabrication of complex 3D structures with sub-micrometer precision. Incorporation of new functionalities into TPL-printed structures is key to advance their applications. A prevalent approach to achieve this is by directly adding functional nanomaterials into the photoresist (called "pre-doping"), which has several inherent challenges including material compatibility, light scattering, and nanoparticle agglomeration. Here, a conceptually different "post-doping" strategy is proposed, where the functionality of the TPL-printed architectures is achieved by impregnating functional materials into their nanoporous 3D mimics. Using the principle of polymerization-induced phase separation, TPL printing of complex microarchitectures with well-defined nanoporous structures having pores of ≈420 nm is realized, which allows spontaneous impregnation of functional liquids via capillary effect. Importantly, unlike the "pre-doping" approach that requires printing optimization for each photoresist, this strategy is highly versatile in terms of functionalities possible. As a proof-of-concept, the impregnation of several functional liquids into TPL-printed porous microstructures is demonstrated: a fluorinated-lubricant, an ionic liquid, and three types of fluorescent liquids, conferring the microstructures with slippery, conductive, and localized fluorescence properties, respectively. Such versatility to fabricate complex microstructures with tailorable and localized functionalities is expected to open new possibilities in wide fields including bionics, electronics, and cell biology.
双光子光刻技术（TPL）能够制造出具有亚微米精度的复杂三维结构。将新功能整合到TPL打印结构中是推动其应用的关键。实现这一目标的一种普遍方法是直接将功能纳米材料添加到光刻胶中（称为“预掺杂”），但这种方法存在一些固有挑战，包括材料兼容性、光散射和纳米颗粒团聚。在此，我们提出了一种概念上不同的“后掺杂”策略，即通过将功能材料浸渍到TPL打印结构的纳米多孔三维模拟物中来实现其功能。利用聚合诱导相分离原理，实现了具有约420纳米孔隙的明确纳米多孔结构的复杂微结构的TPL打印，这使得功能液体能够通过毛细管效应自发浸渍。重要的是，与需要针对每种光刻胶进行打印优化的“预掺杂”方法不同，该策略在可能实现的功能方面具有高度通用性。作为概念验证，展示了将几种功能液体浸渍到TPL打印的多孔微结构中：一种氟化润滑剂、一种离子液体和三种荧光液体，分别赋予微结构光滑、导电和局部荧光特性。这种制造具有可定制和局部功能的复杂微结构的多功能性有望在包括仿生学、电子学和细胞生物学在内的广泛领域开辟新的可能性。
