Functional Shape-Morphing Microarchitectures Fabricated by Dynamic Holographically Shifted Femtosecond Multifoci

Abstract

Functional microdevices based on responsive hydrogel show great promise in targeted delivery and biomedical analysis. Among state-of-the-art techniques for manufacturing hydrogel-based microarchitectures, femtosecond laser two-photon polymerization distinguishes itself by high designability and precision, but the point-by-point writing scheme requires mechanical apparatuses to support focus scanning. In this work, by predesigning holograms combined with lens phase modulation, multiple femtosecond laser spots are holographically generated and shifted for prototyping of three-dimensional shape-morphing structures without any moving equipment in the construction process. The microcage array is rapidly fabricated for high-performance target capturing enabled by switching environmental pH. Moreover, the built scaffolds can serve as arrayed analytical platforms for observing cell behaviors in normal or changeable living spaces or revealing the anticancer effects of loaded drugs. The proposed approach opens a new path for facile and flexible manufacturing of hydrogel-based functional microstructures with great versatility in micro-object manipulation.

Reconfigurable scaffolds for adaptive tissue regeneration

“…On another hand, it is also extremely hard to realize ultra-slow reconfigurations accommodating for the developmental or growing processes of biological tissues within an actuating period from several days to even several months. It will be expected that innovative multidisciplinary efforts, particularly innovations in materials sciences, 137,138 nanoscience, 139 and engineering technologies, 140 should be made for addressing these challenges of reconfigurable scaffolds. In addition, through coupling multiple biophysical cues and/or introducing sensing capabilities to enhance the environmental interactivity of scaffolds, 16,141–144 it can even be envisioned that reconfigurable scaffolds will further obtain superior adaptability, even the “intelligence” of closed-loop control, for matching the extreme physiological complexities among different body tissues.…”

Two‐Photon Polymerization Lithography for Optics and Photonics: Fundamentals, Materials, Technologies, and Applications

“…[348] The focal array can then perform as a fundamental building block in TPL to make macroscale structures with micron scale features. [349][350][351][352] However, using multiple focus array in TPL is not the best option for efficient TPL fabrications, as the fabrication still utilizes single writing voxels. For volumetric microstructures, it is better to use intensity distributions with desired patterns in TPL.…”

Recent Advances on High‐Speed and Holographic Two‐Photon Direct Laser Writing

“…With this multifoci approach it was possible to fabricate a 5 × 5 array of nichoids in just 38 s. Moreover, the authors showed that cell adhesion and proliferation are not affected by the different mechanical properties of nichoids fabricated with a single or multiple foci. Another HoloTPL approach, proposed by J. Chu's group, [ 230 ] exploited dynamic multifoci to fabricate arrays of pH‐sensitive microcages for particle trapping, as well as scaffolds for HeLa cells which can be loaded with drugs for test treatment. The pH‐sensitive scaffolds, reported in Figure A, were fabricated with six foci arranged in a hexagonal geometry, and a 14 µm inscribed circle, which can extend to 27 µm in the culture medium to provide enough space for cell settlement.…”

“…Adapted with permission. [ 230 ] Copyright 2022, American Chemical Society. B) Schematic illustration of the holographic processing of a cylindrical microtube array, and SEM images of arrays with cylindrical, conical drum, and reverse‐drum shapes.…”