Tunicate‐Inspired Gallic Acid/Metal Ion Complex for Instant and Efficient Treatment of Dentin Hypersensitivity

Abstract

Dentin hypersensitivity is sharp and unpleasant pains caused by exposed dentinal tubules when enamel outside of the tooth wears away. The occlusion of dentinal tubules via in situ remineralization of hydroxyapatite is the best method to alleviate the symptoms caused by dentin hypersensitivity. Commercially available dental desensitizers are generally effective only on a specific area and are relatively toxic, and their performance usually depends on the skill of the clinician. Here, a facile and efficient dentin hypersensitivity treatment with remarkable aesthetic improvement inspired by the tunicate-self-healing process is reported. As pyrogallol groups in tunicate proteins conjugate with metal ions to heal the torn body armor of a tunicate, the ingenious mechanism by introducing gallic acid (GA) as a cheap, abundant, and edible alternative to the pyrogallol groups of the tunicate combined with a varied daily intake of metal ion sources is mimicked. In particular, the GA/Fe(3+) complex exhibits the most promising results, to the instant ≈52% blockage in tubules within 4 min and ≈87% after 7 d of immersion in artificial saliva. Overall, the GA/metal ion complex-mediated coating is facile, instant, and effective, and is suggested as an aesthetic solution for treating dentin hypersensitivity.

Grafting of Gallic Acid onto a Bioactive Ti6Al4V Alloy: A Physico-Chemical Characterization

“…The complex compound formation can involve both the carboxylate ion of GA and Ti-O − as donor groups. The formation of the coordination compound influences the chemical reactivity of polyphenols, for instance they are able to polymerize and to form coatings [56,57]: Particularly, in the present case it is shown that they were much more prone to be grafted on a surface. The possible formation of the complex and its binding to the surface is reported in Figure 2.…”

“…A not negligible amount of calcium ion was detected on the samples functionalized in SBF (CT_GA_SBF_1, CT_GA_SBF_2) while negligible amount of calcium ion was observed on one sample functionalized in PBS (CT_GA_PBS_1): In this case, due to the very low amount and absence in PBS solution (at least theoretically), it can be considered a contamination. The presence of calcium on the samples incubated in the source solutions with SBF as medium, can be related to the GA ability to bind this element [8,30] within a complexation reaction [49,56]. It is reported [48,56] that polyphenols are prone to give complexation reactions in solutions containing metal ions; the structure of the coordination compounds can be different depending on the pH of the solution.…”

“…The presence of calcium on the samples incubated in the source solutions with SBF as medium, can be related to the GA ability to bind this element [8,30] within a complexation reaction [49,56]. It is reported [48,56] that polyphenols are prone to give complexation reactions in solutions containing metal ions; the structure of the coordination compounds can be different depending on the pH of the solution. At pH values higher than 6 can be hypothesized that a heterogeneous ternary coordination compound is formed with the metal ions in a central position.…”

“…The ability of polyphenols to attract and bind calcium ions could have an influence also in the induced precipitation of hydroxyapatite during soaking in SBF (see Section 3.4) [56] as already observed by the authors in the case of surface functionalization of bioactive glasses with GA [30]. The absence of calcium in the PBS medium can explain the significantly lower amount of GA grafted on the surfaces exposed to source solutions prepared with this medium: The presence of a metal ion forming complex with polyphenols is crucial for their grafting.…”

Gallol‐Tethered Injectable AuNP Hydrogel with Desirable Self‐Healing and Catalytic Properties

“…Tunicate, a marine invertebrate organism that encapsulates its body into a thick membrane called a tunic, exhibits a prominent self‐healing ability under seawater environment (≈8 pH) . Gallol‐functionalized 3,4,5‐trihydroxyphenylalanine (TOPA) plays an essential role in healing injuries, because gallol moieties in TOPA generate covalent cross‐linkage with functional groups and other proteins in the body of tunicate . Inspired by tunicate, tannic acid (TA), a representative gallol‐rich compound, was reported to be tethered to gelatin via Michael addition reaction under oxidizing conditions to produce biocompatible adhesives with intrinsic antibacterial ability .…”