Remotely Self-Healable, Shapeable and pH-Sensitive Dual Cross-Linked Polysaccharide Hydrogels with Fast Response to Magnetic Field

Abstract

The development of actuators with remote control is important for the construction of devices for soft robotics. The present paper describes a responsive hydrogel of nontoxic, biocompatible, and biodegradable polymer carboxymethyl hydroxypropyl guar with dynamic covalent cross-links and embedded cobalt ferrite nanoparticles. The nanoparticles significantly enhance the mechanical properties of the gel, acting as additional multifunctional non-covalent linkages between the polymer chains. High magnetization of the cobalt ferrite nanoparticles provides to the gel a strong responsiveness to the magnetic field, even at rather small content of nanoparticles. It is demonstrated that labile cross-links in the polymer matrix impart to the hydrogel the ability of self-healing and reshaping as well as a fast response to the magnetic field. In addition, the gel shows pronounced pH sensitivity due to pH-cleavable cross-links. The possibility to use the multiresponsive gel as a magnetic-field-triggered actuator is demonstrated.

Stimuli-Responsive Polysaccharide-Based Smart Hydrogels and Their Emerging Applications

“…A similar electronic response was reported for a cellulose/chitosan hybrid gel that showed high electronic conductivity and is likely to be used in biodevices and soft actuators . Further, carboxymethyl hydroxypropyl guar gum hydrogel functions as a magnetic-field triggered actuator . Due to the dynamic nature of the cross-links, the borate and NPs cross-links allow the gel to deform rapidly, which is reversible.…”

“…169 Further, carboxymethyl hydroxypropyl guar gum hydrogel functions as a magnetic-field triggered actuator. 170 Due to the dynamic nature of the cross-links, the borate and NPs cross-links allow the gel to deform rapidly, which is reversible. Simultaneously, reversible "on−off" swelling behavior triggered by physiological signals has enabled the design of sensors, micromanipulators, robotic, and optical systems to manage the flow of liquids in microfluidics.…”

A novel triple-network hydrogel based on borate ester groups: from structural modulation to rapid wound hemostasis

“…The hydrogel material obtained through covalent crosslinking has a stable network structure and high mechanical properties; [1][2][3] therefore, it is difficult to change the structure once it is formed, 4 and the ''adaptivity'' of its shape is somewhat limited. However, non-covalent cross-linked hydrogel materials contain a large number of dynamic chemical bonds, [5][6][7][8][9] to effectively achieve a perfect fit between the hydrogel and the wound, 10 and their self-adaptive ability is significantly improved. 11 In addition, non-covalent cross-linked hydrogel materials have a wide range of applications in intelligent sensing, 12,13 biomedicine 14 and other fields.…”

Magnetic Self-Healing Composites: Synthesis and Applications

“…Similarly, Shibaev et al developed a dual-crosslinked hydrogel combining particle-polymer hydrogen bonds and dynamic borate crosslinks. The soft composite exhibits pH responsiveness via borate ion cleavage and efficient magnetic actuation [87]. In addition to magnetic fields, near-infrared-light (NIR) irradiation has been studied as a stimulus for magnetic self-healing elastomers using magnetic particles as photothermal conversion agents.…”