Fabrication of a self-healing hydrogel with antibacterial activity using host-guest interactions between dopamine-modified alginate and β-cyclodextrin dimer

Self-healing hydrogels possess an ability to recover their functionality after experiencing damage by regenerating cross-links. The main challenge in making self-healing hydrogels based on host-guest (HG) interactions is their limited mechanical strength, which can be solved using beta-cyclodextrin dimers (β-CDsD). Here, β-CDsD as a host cross-linker was used to increase the mechanical property of the HG interactions. Alginate with acceptable biocompatibility was modified by dopamine (ALG-DOP) and employed as a guest polymer. Self-healing hydrogel was developed between them, and Ag nanoparticles were added to create an antibacterial activity. Dopamine with appropriate size and suitable adhesiveness established HG interactions with β-CDsD, and cells were able to grow well on hydrogel. This hydrogel showed an impressive self-healing capability <5 min. These hydrogels revealed a respectable porosity from 15 to 55 μm essential for exchanging the substances required for cell growth and cell waste elimination. Biocompatibility was investigated against NIH 3 T3 fibroblasts cells, and the results showed that the cells grew well. The in vitro release of curcumin from the hydrogel was examined in PBS at pH of 7.4. The hydrogel can be a perfect candidate for controlled drug release, and wound-dressing due to self-healing property, antibacterial activity, adhesion, and biocompatibility.

Nanomagnetic Cyclodextrin decorated with ionic liquid as green and reversible Demulsifier for breaking of crude oil emulsions

Application of the chemical demulsifiers is the best choice for breaking the water in crude oil (W/O) emulsions in the petroleum industry. Here, novel, environmentally friendly, efficient, and easily reusable Fe3O4 nanomagnetic compounds based on imidazolium-decorated cyclodextrin were successfully synthesized and applied to demulsify the water in crude oil (W/O) emulsions. At first, Fe3O4 nanoparticles were decorated with β-cyclodextrin (β-CD) to prepare Fe3O4@β-CD@IL magnetic nanoparticles. Then, imidazole (Im) was separately reacted with 1-bromohexane and 1-bromodecane to prepare [Im-C6][Br] and [Im-C10][Br] ionic liquids, respectively. The prepared imidazolium-based ionic liquids were reacted with N-propyltriethoxysilane to synthesize [ImSi-C6][Br] and [ImSi-C10][Br]. Finally, [ImSi-Cn][Br] was immobilized on Fe3O4@β-CD to obtain nanomagnetic demulsifiers. Structure of the synthesized compounds was confirmed using different methods such as FT-IR, NMR, and elemental analysis. TGA, VSM, and FESEM methods were used to investigate the thermal stability, magnetic properties, and the morphology, respectively. Fe3O4@βCD and Fe3O4@βCD@[ImSi-C10][Br] nanoparticles respectively showed the particle size in the range of 40-70 nm and 50-80 nm. After grafting the imidazolium-based ionic liquid on the surface of support, the magnetization number reduced from 25.6 emu/g for Fe3O4@β-CD to 24.9 emu/g for Fe3O4@β-CD@[ImSi-C10][Br]. Synthesized material employed to break the (10:90 and 30:70 Vol%) W/O emulsions at the concentration range of 1000-5000 ppm. The maximum demulsification efficiency (DE%) of 92 % was obtained using a Fe3O4@β-CD@[ImSi-C10][Br] at 5000 ppm for (30:70 Vol%) W/O emulsion within 24 h. Interfacial tension (IFT) values decreased with increasing the DE%. The Fe3O4@βCD@[ImSi-C10][Br] demulsifier was reused five times with acceptable yields. The cooperation of imidazolium and β-CD in the green nanomagnetic demulsifiers led to the efficient demulsification of the W/O emulsions. The preparation of different ionic liquids or changing the counter anions are our potential future directions for this research. Demulsification at high demulsifier concentration can be considered a limitation of the nanomagnetic cyclodextrin decorated with ionic liquid. But due to the low amount of ionic liquid immobilized in the synthesized demulsifier, the cost of the final demulsifier is lower that other demulsifiers with full ionic liquid backbones, which increases its potential for industrial applications.

MXene/zinc ion embedded agar/sodium alginate hydrogel for rapid and efficient sterilization with photothermal and chemical synergetic therapy

Bacterial infections can significantly impair wound healing. Therefore, it is essential to develop wound dressings with high antimicrobial activity. Hydrogels are often used as wound dressings due to their excellent physicochemical properties. Herein, by cross linking sodium alginate (SA), agar (AG) with Ti3C2Tx MXene and Zinc ions (Zn2+), a biosafe composite hydrogel (MSG-Zn2+) was developed for fast and efficient sterilization treatment. The excellent photothermal properties of Ti3C2Tx MXene and the chemical antimicrobial activity of Zn2+ enable synergistic photothermal therapy (PTT)/chemical therapy in NIR biowindow with reduced power density and improved antimicrobial efficiency. More importantly, the incorporation of Zn2+ can enhance the effective contact between the hydrogel and bacteria, benefiting both photothermal and chemical antibacteria. In vitro antibacterial experiments showed that MSG-Zn2+ has a broad-spectrum antibacterial effect against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). Cellular experiments showed that the hydrogel had excellent biocompatibility and the released Zn2+ stimulated cell migration. In addition, the prepared MSG-Zn2+ hydrogel has other advantages such as hydrophilic, high swelling, simple and low cost preparation, which meets the requirements of an economical wound dressing. This proposed work shows that this composite hydrogel MSG-Zn2+ has great potential for practical antimicrobial wound dressing applications.

Magnetite embedded κ-carrageenan-based double network nanocomposite hydrogel with two-way shape memory properties for flexible electronics and magnetic actuators

Shape memory hydrogels attract increasing attention as flexible strain sensors due to their shape recovery property that can improve the lifetime of the sensor. Herein, we have designed a magnetic shape memory hydrogel based on Fe₃O₄ nanoparticles, carrageenan, and poly (acrylamide-co-acrylic acid) with self-adhesive and conductive properties. The resulting double network hydrogel showed promising actuator and strain sensor applications. Electrical conductivity was observed in this hydrogel without using additional ions. The presence of magnetite nanoparticles increased the tensile strength and temporary shape fixity ratio to around 6.5 MPa and 94.3 %, respectively. The excellent cantilever and catheter-like behavior of the hydrogels were illustrated through magnetic routing by an external magnet. Also, these hydrogels demonstrated suitable performance in the 500 cycles strain sensing tests before and after their initial shape recovery.

Regenerable bacterial killing–releasing ultrathin smart hydrogel surfaces modified with zwitterionic polymer brushes

Building long-lasting antimicrobial and clean surfaces is one of the most effective strategies to inhibit bacterial infection, but obtaining an ideal smart surface with highly efficient, controllable, and regenerative properties still encounters many challenges. Herein, we fabricate an ultrathin brush–hydrogel hybrid coating (PSBMA-P(HEAA-co-METAC)) by integrating antifouling polyzwitterionic (PSBMA) brushes and antimicrobial polycationic (P(HEAA-co-METAC)) hydrogels. The smart bacterial killing–releasing properties can be achieved independently by the opposite volume and conformation changes between the swelling (shrinking) of P(HEAA-co-METAC) hydrogel layer and the shrinking (swelling) of PSBMA brushes. The friction test reveals that both METAC and SBMA components support great lubrication. By tuning the initial organosilane (BrTMOS:KH570) ratios, the prepared PSBMA-P(HEAA-co-METAC) coating exhibits different antibacterial abilities from single “capturing–killing” to versatile “capturing–killing–releasing.” Most importantly, 99% of the bacterial-releasing rate can be easily achieved via 0.5 M NaCl treatment. This smart surface not only possesses long-lasting antibacterial performance, only ∼1.09 × 105 cell·cm−2 bacterial residue even after 72 h exposure to bacteria solutions, but also can be regenerated and triggered between water and salt solution multiple times. This work provides a new way to fabricate antibacterial smart hydrogel coatings with bacterial “killing–releasing” functions and shows great potential for biomedical applications.