Super-Rapid In Situ Formation of a Silver Ion-Induced Supramolecular Hydrogel with Efficient Antibacterial Activity for Root Canal Disinfection

Supramolecular hydrogels prepared using low-molecular-weight gelators have attracted considerable attention for biomedical applications. However, in situ supramolecular hydrogels are limited in terms of their prolonged gelation time and/or unstable nature at high temperatures. In this study, we constructed a stable supramolecular Ag-isoG hydrogel through super-rapid in situ formation, wherein hydrogelation process occurred instantaneously upon mixing isoG and Ag⁺ within 1 s under ambient conditions. Interestingly, unlike most nucleoside-based supramolecular hydrogels, this Ag-isoG hydrogel remains stable even at a high temperature (100 °C). Moreover, the as-designed hydrogel demonstrated significant antibacterial activity against Staphylococcus aureus and the oral bacterium Streptococcus mutans owing to the strong chelating ability of Ag ions, and the hydrogel exhibited relatively low cytotoxicity in root canal and an easy removal feature by saline. The hydrogel was then applied to a root canal infection model, which demonstrated strong antibacterial activity against Enterococcus faecalis, with performance even better than that of the regular calcium hydroxide paste. This feature makes the Ag-isoG hydrogel a prospective alternative material as intracanal medicaments for root canal treatment.

Green Wood Adhesives from One-Pot Coacervation of Folic Acid and Branched Poly(ethylene imine)

Adhesives are extensively used in furniture manufacture, and most currently utilized furniture glues are formaldehyde-based chemicals, which emit formaldehyde throughout the entire life of the furniture. With increasing concerns about formaldehyde emission effects on human health, formaldehyde-free and environmentally friendly wood adhesives from bio-based resources are highly desired. In this study, we developed an eco-friendly, high-strength, and water-based wood adhesive from one-pot coacervation of the hierarchical self-assembly of folic acid (FA, a biomolecule, vitamin B9) with a commercially available biocompatible polymer-branched poly(ethylene imine) (b-PEI). The coacervation is caused by multiple hydrogen bonds between b-PEI and the stacks of FA quartets, which demonstrates a continuous robust 3D network, thus realizing adhesion and cohesion behaviors. This coacervate has the strongest adhesion toward wood compared with other substrates. The long-lasting shear bonding strength is up to 3.68 MPa, which is much higher than that of commercial super glue, but without releasing any toxic components. Since all the fabrication and application processes are under ambient conditions without any heating and high-pressure procedures, this work provides a facile yet powerful strategy to develop formaldehyde-free, eco-friendly, and high-performance bio-based waterborne adhesives for wood bonding.