Stabilization of [poly(allylamine)–tannic acid]_n multilayer films in acidic and basic conditions after crosslinking with NaIO₄

Abstract

Interaction of NaIO4 with (PAH–TA)n films: stabilization in strong acid and basic solutions and changes in the film permeability.

Silicic Acid-Mediated Formation of Tannic Acid Nanocoatings

“…In addition, the intrinsic autoxidation in aqueous solution can initiate the polymerization of polyphenolic molecules that enables the coating formation. , The oxidation of phenolic hydroxyl groups by dissolved oxygen forms quinones and semiquinones, which couple via secondary interactions, such as hydrogen bonding, interaction of electron donor–acceptor systems (π-stacking), or proceed to form primary bonds . In the latter case, new inter- and intramolecular C–C and C–O bonds are formed via a cascade of radical reactions. , …”

Modulating the Antioxidant Activity of Thin Layer-by-Layer Films with Polyphenols

“…The deposition of (PAH-TA) n films (5min per adsorption and rinsing step as in ref. [12]) was characterized by means of UV-vis spectroscopy (Figure 2) and by contact angle goniometry (Figure 3). The film growth is of linear type, meaning that the absorbance increases at λ=300nm, due to TA (PAH does not absorb light above λ=200nm), scales in proportion to the number of deposited layer pairs (Figure 2).…”

“…The morphology of the (PAH-TA) n films has also been characterized by means of Atomic Force Microscopy and some typical images acquired in the contact mode and in the dry state can be found in Figure 4 of ref. [12]. The (PAH-TA) n films display some antioxidant activity as quantified through a decrease in absorbance at λ=517nm, typical of the transformation of the purple DPPH into the yellowish DPPH-H (Figure 1).…”

“…The LBL deposition was performed as described in ref. [12]. Briefly: the cleaned quartz slide was dipped during 5min in the PAH solution, in sodium acetate buffer, in the TA solution and again in sodium acetate buffer.…”

Impacts of Resveratrol and Pyrogallol on Physicochemical, Mechanical and Biological Properties of Epoxy-Resin Sealers

“…In the current study, incorporation of the tested polyphenols was performed into the base part (Table 1) of the epoxy resin-based sealer. We believe that since the catalyst part of the epoxy resin contains amines, oxidation of PY could have activated the polymerization and/or reduced beneficial effects of the phenolic compounds via formation of covalent bonds with the amines [23]. One of the first outcomes obtained in this study was that the control (free of polyphenols) sealer had some antibacterial effects against E. faecalis after 24 h. Ruiz-Linares et al [24] analyzed an epoxy resin-based sealer (AH-Plus, Dentsply Sirona, Konstanz, Germany) against E. faecalis and they showed that such material could induce some antibacterial effects as a result of the release of formaldehyde and/or other toxic non-polymerized components, such as amines or epoxy monomers.…”