Biodegradable Magnetic Hydrogel Robot with Multimodal Locomotion for Targeted Cargo Delivery

Abstract

Recent strides in the development of untethered miniature robots have shown the advantages of diverse actuation methods, flexible maneuverability, and precise locomotion control, which has made miniature robots attractive for biomedical applications such as drug delivery, minimally invasive surgery, and disease diagnosis. However, biocompatibility and environmental adaptability are among the challenges for further in vivo applications of miniature robots due to the sophisticated physiological environment. Herein, we propose a biodegradable magnetic hydrogel robot (BMHR) that possesses precise locomotion with four stable motion modes, namely tumbling mode, precession mode, spinning-XY mode, and spinning-Z mode. Using a homemade vision-guided magnetic driving system, the BMHR can achieve flexible conversion between the different motion modes to cope with changes in complex environments, and its superior ability to cross obstacles is demonstrated. In addition, the transformation mechanism between different motion modes is analyzed and simulated. Benefiting from the diverse motion modes, the proposed BMHR has promising applications in drug delivery, showing remarkable effectiveness in targeted cargo delivery. The BMHR’s biocompatible property, multimodal locomotion, and functionality with drug-loaded particles can provide a new perspective to combine miniature robots with biomedical applications.

Magnetoactive Millirobots with Ternary Phase Transition

“…Note that although the phase transition temperature of the gelatin-based millirobot in Figure e is lower than the human body temperature, we can use other thermosensitive polymers to solve this issue. Biocompatible materials including pectin, agar, PVA, , and carrageenan , are widely used to improve the transition temperature of gelatin. For instance, a microrobot based on the gelatin–carrageenan hybrid hydrogel shows a phase transition temperature of 42 °C, which is greater than the temperature within the human stomach (37–38 °C).…”

“…Biocompatible materials including pectin, agar, PVA, , and carrageenan , are widely used to improve the transition temperature of gelatin. For instance, a microrobot based on the gelatin–carrageenan hybrid hydrogel shows a phase transition temperature of 42 °C, which is greater than the temperature within the human stomach (37–38 °C). We place the solid-phase millirobot into the stomach model and move it on the gastric wall (i–ii).…”

“…For instance, extreme acidic conditions can seriously affect the stability of the gelatin-based millirobot. Methods of modifying/coating gelatin by other acid-resistant biocompatible polymers such as chitosan − and alginate/Ca hydrogel ,− could be promising ways to solve this issue. In the future, the comprehensive implementation of adapting to an acidic environment could be explored for clinic application.…”

Polysaccharide-Based Micro/Nanomotors for Active Ingredient Delivery in Food

“…Since the 21st century, MNMs have attracted the attention of numerous researchers due to their advantages such as self-propulsion and precise positioning within a small range, and the study of MNMs has become an interdisciplinary cutting-edge research field. The driving force of MNMs has multiple sources, mainly categorized as chemical energy-driven, such as the commonly used hydrogen peroxide propulsion, physically driven by external fields like light field, , magnetic field, , acoustic field, and electric field, and biocatalytically driven by enzymes such as catalase, glucose oxidase, urease, etc. The scientific community has mostly focused on the application research of MNMs in the biomedical field, , with applications in the food sector needing further supplementation and expansion.…”

Recent Progress of Anti-Freezing, Anti-Drying, and Anti-Swelling Conductive Hydrogels and Their Applications

“…Flexible conductive materials can convert external stimuli, such as stress, strain, temperature, and humidity, into electrical signals (such as current, resistance, and capacitance) [1][2][3]. Due to their unique stimuli-responsive characteristics, flexible conductive materials are commonly used in research fields such as human motion monitoring [4], human health monitoring [5], remote medical control [6], artificial skin [7], and soft robotics [8]. Traditional flexible conductive materials usually consist of flexible substrate materials (PDMS, polyurethane, polyetherimide, and Ecoflex) and rigid conductive materials (such as metal nanomaterials, carbon-based materials, and conductive polymers).…”