Environmentally Adaptive Shape-Morphing Microrobots for Localized Cancer Cell Treatment

Abstract

Microrobots have attracted considerable attention due to their extensive applications in microobject manipulation and targeted drug delivery. To realize more complex micro-/nanocargo manipulation (e.g., encapsulation and release) in biological applications, it is highly desirable to endow microrobots with a shape-morphing adaptation to dynamic environments. Here, environmentally adaptive shape-morphing microrobots (SMMRs) have been developed by programmatically encoding different expansion rates in a pH-responsive hydrogel. Due to a combination with magnetic propulsion, a shape-morphing microcrab (SMMC) is able to perform targeted microparticle delivery, including gripping, transporting, and releasing by “opening–closing” of a claw. As a proof-of-concept demonstration, a shape-morphing microfish (SMMF) is designed to encapsulate a drug (doxorubicin (DOX)) by closing its mouth in phosphate-buffered saline (PBS, pH ∼ 7.4) and release the drug by opening its mouth in a slightly acidic solution (pH < 7). Furthermore, localized HeLa cell treatment in an artificial vascular network is realized by “opening–closing” of the SMMF mouth. With the continuous optimization of size, motion control, and imaging technology, these magnetic SMMRs will provide ideal platforms for complex microcargo operations and on-demand drug release.

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

“…Among existing approaches to printing hydrogel, femtosecond direct laser writing (DLW) enabled by TPP is extensively studied for processing complex microarchitectures, − owing to its three-dimensional (3D) programmability and high printing resolution. , Multiple materials with distinct properties can also be integrated by DLW structuring technique to realize functionalities beyond the capability of a single material. ,, To improve the fabrication throughput of the point-by-point writing strategy, galvo-mirrors have been utilized to support high-speed focus scanning . Another efficient method is to generate multifoci arrays or structured beams by a spatial light modulator (SLM). − Holographic processing of pH-triggered microactuator by Bessel beam has been recently reported .…”

Multi-material 3D printing-enabled multilayers for smart actuationviamagnetic and thermal stimuli

“…5,6 With proper manipulation of the external fields and appropriate materials (i.e., SMPs containing nanoparticles for advanced hybrids or composites), SMPs can function efficiently with reversible shape transformation or precise motions. 7 Even though many external stimuli can control shape memory effects, not all are favorable for providing both hovering and translational motions essential for an active robot. For example, the commonly used heat and light stimulation can perform an actuation in a fixed position and change the footprint (e.g., area and volume), but will find it challenging to constantly move the object in space (e.g., dark outer space).…”

“…, SMPs containing nanoparticles for advanced hybrids or composites), SMPs can function efficiently with reversible shape transformation or precise motions. 7…”

Aligned Magnetic Nanocomposites for Modularized and Recyclable Soft Microrobots

“…7,9−14 Miniature soft robots, with the size ranging from micrometers to millimeters, have attracted particular attention due to their capability of noninvasively accessing narrow and confined spaces, and thus possess high potential for medical and bioengineering applications. 14−16 Significant advances have been lately achieved in developing miniature soft robots, which are generally constructed by different types of smart materials and actuated via various external stimuli such as light, 24−27 heat, 9,11 chemicals, 14,28 humidity, 29,30 and acoustic and electromagnetic fields. 1,2,5,21,31−34 By deliberately designing the structure and tuning the properties of the responsive materials inside the robots, heterogeneous and asymmetrical deformation can be generated in a programmed manner.…”