3D Printed Enzymatically Biodegradable Soft Helical Microswimmers

Abstract

Mobile micro-and nanorobots have been proposed for future biomedical applications, such as diagnostics and targeted delivery. For their translation to clinical practice, biocompatibility and biodegradability of micro-and nanorobots are required aspects. The fabrication of smallscale robots with non-cytotoxic biodegradable soft components will allow for enhanced device assimilation, optimal tissue interaction and minimized immune reactions. We report the 3D microfabrication of biodegradable soft helical microswimmers via two-photon polymerization of the nontoxic photocrosslinkable hydrogel gelatin methacryloyl (GelMA). GelMA microswimmers are fabricated with user-defined geometry and rendered magnetically responsive by decorating their surface with magnetic nanoparticles. In contrast to previous rigid helical microrobots, our soft helical microswimmers can corkscrew above the step-out frequency with relatively high values of forward velocity, suggesting an unprecedented selfadaptive behavior. Cytotoxicity assays show the toxicity of GelMA is at least three orders of

Flexible Ferrofluids: Design and Applications

“…Combining the advantages of field responsive ferrofluids and curable soft materials, magnetically responsive soft robots with different shapes could be fabricated and widely used, such as cilia‐like, columnar, helical, film‐shaped, mesh‐like, etc . They have found various applications in drug delivery, wettability manipulation, anti‐icing, water purification, and optical transmission.…”

It's in the Fine Print: Erasable Three‐Dimensional Laser‐Printed Micro‐ and Nanostructures

“…di(meth)acrylates), while DLW applications often require tri‐ or tetrafunctional crosslinkers (e.g. pentaerythritol triacrylate (PETA)) to fabricate structures with fine details …”

“…With regard to spatial control, cleaving a material can be divided into three categories: 1) no spatial control, 2) partial spatial control, and 3) complete spatial control (Figure ). No spatial control (category 1) is the easiest to achieve and requires a photoresist that can be degraded by a homogeneous external condition, such as pH, temperature, specific additives, or enzymes . Complete cleavage without spatial control is particularly interesting, for example in drug delivery, when the cargo is only transported by a direct‐laser‐written structure and cleavage is used for controlled cargo release .…”

“…A large body of work has been established that extensively exploits the controlled cleavage of networks via labile moieties, such as gels, solid‐phase organic synthesis, drug‐delivery systems, and biodegradable polymers, among others . However, research regarding cleavable 3D printed materials fabricated in the submicron range is still challenging and only a few examples have been reported so far, which will be discussed in the next Section . Consequently, the translation of existing knowledge for the next generation of DLW photoresists is of significant value for the design of degradable micro‐ and nano‐sized printed 3D materials.…”

“…and Ceylan et al. fabricated hydrogel microswimmers based on gelatin methacryloyl (Figure ) . Their magnetically actuated microswimmers, with dimensions in the micron‐range (6 μm in diameter by Ceylan et al.…”