Mussel‐Inspired Adhesive and Conductive Hydrogel with Long‐Lasting Moisture and Extreme Temperature Tolerance

Abstract

Conductive hydrogels are a promising class of materials to design bioelectronics for new technological interfaces with human body, which are required to work for a long-term or under extreme environment. Traditional hydrogels are limited in short-term usage under room temperature, as it is difficult to retain water under cold or hot environment. Inspired by the antifreezing/antiheating behaviors from nature, and based on mussel chemistry, an adhesive and conductive hydrogel is developed with long-lasting moisture lock-in capability and extreme temperature tolerance, which is formed in a binary-solvent system composed of water and glycerol. Polydopamine (PDA)-decorated carbon nanotubes (CNTs) are incorporated into the hydrogel, which assign conductivity to the hydrogel and serve as nanoreinforcements to enhance the mechanical properties of the hydrogel. The catechol groups on PDA and viscous glycerol endow the hydrogel with high tissue adhesiveness. Particularly, the hydrogel is thermal tolerant to maintain all the properties under extreme wide tempreature spectrum (−20 or 60 °C) or stored for a long term. In summary, this mussel-inspired hydrogel is a promising material for self-adhesive bioelectronics to detect biosignals in cold or hot environments, and also as a dressing to protect skin from injuries related to frostbites or burns.

Rational Fabrication of Anti‐Freezing, Non‐Drying Tough Organohydrogels by One‐Pot Solvent Displacement

“…[1][2][3][4] To date,n umerous advances about hydrogels have been made,i ncluding the synthesis,a pplication, and engineering of various hydrogels. [15] Theu se of abinary solvent system has enabled the successful fabrication of anti-freezing hydrogels with long-term application capability.However,owing to the introduction of abinary solvent during the polymerization step,s pecific synthetic conditions are required to be optimized carefully to meet the polymerization behavior of different monomers.T aking into account alarge number of different hydrogels,therefore,there is still aneed to develop amore versatile and convenient strategy to fabricate anti-freezing and non-drying hydrogels.Inspired by the cryopreservation of biological samples (for example,p rotein crystals,b acteria, and cells) at extremely cold conditions, [16] herein, we report as imple, reliable,a nd versatile strategy,s o-called "solvent displacement", to fabricate anti-freezing,n on-drying tough organohydrogels.I nt his strategy,w ater molecules in the hydrogels are displaced by immersing the hydrogels in acryoprotectant (CPA) solution (for example,g lycerol, glycol, sorbitol, or mixtures of these CPAs). Recently,s everal remarkable efforts were made to address the above two flaws.For example,Liu and co-workers reported the use of water and oil as the dispersion medium to fabricate adaptive and freeze-tolerant hetero-network organohydrogels,w hich inhibited the ice crystallization of the hydrogel components,leading to enhanced mechanical properties over aw ide temperature range from À78 to 80 8 8C.…”

“…Recently,s everal remarkable efforts were made to address the above two flaws.For example,Liu and co-workers reported the use of water and oil as the dispersion medium to fabricate adaptive and freeze-tolerant hetero-network organohydrogels,w hich inhibited the ice crystallization of the hydrogel components,leading to enhanced mechanical properties over aw ide temperature range from À78 to 80 8 8C. [15] Theu se of abinary solvent system has enabled the successful fabrication of anti-freezing hydrogels with long-term application capability.However,owing to the introduction of abinary solvent during the polymerization step,s pecific synthetic conditions are required to be optimized carefully to meet the polymerization behavior of different monomers.T aking into account alarge number of different hydrogels,therefore,there is still aneed to develop amore versatile and convenient strategy to fabricate anti-freezing and non-drying hydrogels. [14] Similarly,L ua nd co-workers reported the use of ag lycerol-water binary solvent to fabricate hydrogels with long-lasting weight retention at temperatures ranging from À20 to 60 8 8C.…”

Effect of Mussel‐Inspired Poly(Dopamine)‐Functionalized Carbon Nanotubes/Graphene Nanohybrids on Interfacial Adhesion of Soy Protein‐Based Nanocomposites

“…The interfacial adhesion between the functionalized PDCNTs and SPI matrix was significantly increased by the covalent bonding between the two phases, which absorbed much energy and hindered the mutual slippage of graphene sheets . In addition, the incorporation of the PDA layers with functional groups on the surface of CNTs could lead to a good dispersibility of PDCNTs in the SPI matrix, and hydrogen bonding was formed between the hydroxyl groups on PDCNTs surface and the carbonyl groups of SPI chains . When compared with the neat SPI film, the EB of SPI/G/PDCNTs film was significantly increased from 90.77% to 162.18%, which was due to the enhanced interfacial interactions and adhesion effect between the PDCNTs and SPI matrix .…”

Using Artificial Skin Devices as Skin Replacements: Insights into Superficial Treatment

“…Nevertheless, a shortcoming of hydrogels lies in their tendency to dehydrate when left exposed in air, resulting in a change of properties. One way to prevent this is the addition of hygroscopic substances into the gel network such as salts or small molecules into the network, which increases the affinity for water in the gel. Using an alternative strategy, Zhao and co‐workers devised a hydrogel‐elastomer hybrid through the surface modification of an elastomer layer .…”