Fully Programmable Collective Behavior of Light‐Powered Chemical Microrobotics: pH‐Dependent Motion Behavior Switch and Controlled Cancer Cell Destruction

Abstract

The development of fuel‐free light‐powered multi stimuli‐responsive microrobots is becoming a vital field in biomedical research. The challenge is to design biomedical robots with precise motion control and novel functionalities such that one day they will stand alongside medical staff as fully fledged partners in the delivery of advanced non‐invasive therapeutic procedures. In this study, a simple one‐step etching/polymerization procedure is used to fabricate crystalline metal‐organic framework structures surface‐coated with a conductive polypyrrole (PPy) layer and then enriched with Methylene Blue sensitizer molecules. Due to the PPy surface charge, the microrobots start to move when exposed to a visible light source, enabling the controllable accumulation of the microrobots at the focal point of the light beam. Furthermore, a self‐regulated motion is achieved by the PPy surface charge also providing a pH‐dependent switch capable of altering microrobot behavior. In vitro study is conducted to test microrobot efficiency against human cervix carcinoma HeLa cells. It is shown that the micromotors are able to penetrate and successfully destroy the cancer cells. The work provides proof‐of‐concept for a novel strategy in which such microrobots can be guided by an optical beam, can self‐regulate movement toward or away from each other, and can perform therapeutic functions with great efficiency.

Advances in Finite Element Analysis of External Field‐Driven Micro/Nanorobots: A Review

“…Light-driven MNRs have advantages for MNR control strategies because of their high spatiotemporal responsiveness and control application. [69] Light-driven MNRs are generally made of photoactive materials (e.g., photocatalytic materials), and under the irradiation of light, they will cause photochemical reactions, photothermal conversion, and other chemical reactions. [32,70] The propulsion force of light-driven MNRs is mainly generated by an induced asymmetric gradient field.…”

The rise of metal–organic framework based micromotors

“…The mechanism relies on the MM accumulation in the tumour area (induced by its collective behaviour) along with a combination of ROS generation and photothermal action due to the photophoretic mechanism. 65 In another excellent example of cooperative MOFs MM action, NH 2 -MIL-101 based MMs were assembled by asymmetric modification with polyethylene glycol and glutathione hydrolase g-glutamyltransferase. The MMs exhibit a chemotactic effect induced by the excess of glutathione in tumours.…”

“…The radical oxygen species (ROS) generated during the MM motion were exploited for in vitro Hella cell disruption. 65 NIR light has been also explored for MOF-based MM propulsion. Thus, mesoporous polydopamine (PDA) nano bowls have been used both as a template and as a carrier of UiO-66 MOFs.…”

Chemical tunability of advanced materials used in the fabrication of micro/nanobots

“…In yet another example, iron oxide metal–organic framework (MIL)-based versatile microrobots synthesized using a single-step etching process were reported. 99 The microrobots were surface-functionalized with PPy and further supplemented with methylene blue (MB) sensitizer molecules (Fig. 9a–c).…”