Allantoin‑zinc layered simple hydroxide biohybrid as antimicrobial active phase in cellulosic bionanocomposites as potential wound dressings

Cellulosic materials loaded with a novel zinc layered simple hydroxide (LSH) with allantoin in its structure (allant-ZnLSH) have been developed for potential application as wound dressings. The allant-ZnLSH biohybrid was synthesized by slow addition of a zinc chloride solution to an aqueous solution of allantoin, while adding a NaOH solution dropwise to maintain a controlled pH. The recovered precipitate was characterized by XRD, FTIR, chemical analysis, and FE-SEM. The allant-ZnLSH material was further incorporated into biopolymeric matrices such as hydroxypropylmethylcellulose (HPMC), carboxymethylcellulose (CMC) and cellulose nanofibers (CNF), because of their biocompatibility and biodegradability. The resulting films presented suitable mechanical properties, with Young's modulus values ranging between 1.3 and 3.9 GPa, as well as appropriate water vapor transmission rates (WVTR) for application in would healing, around 250–630 g/m2 per day. The bionanocomposite films also showed interesting barrier properties against the passage of UV light, while keeping a certain transparency in the visible range that would allow the healing process to be monitored without removing the dressing. Their antibacterial action was evaluated against E. coli and S. aureus in agar plates, showing only antimicrobial activity against the latter. The goal is to develop materials that can exhibit antimicrobial, and skin regenerative properties provided by the presence of zinc ions and allantoin, respectively.