Preparation and characterization of porous membranes of glucomannan and silver decorated cellulose nanocrystals for application as biomaterial.

Bacterial infection usually represents a threat in medical wound care, due to the increase in treatment complexity and the risk of antibiotic resistance. For presenting interesting characteristics for the use as biomaterial, natural polymers have been explored for this application. Among them, a promising candidate is the konjac glucomannan (KGM) with outstanding biocompatibility and biodegradability but lack of antibacterial activity. In this study, KGM was combined with silver decorated cellulose nanocrystals (CNC-Ag) to prepare membranes by using a recent reported casting-freezing method. The results highlight the potential anti-adhesive activity of the new materials against Staphylococcus aureus upon contact, without the burst release of silver nanoparticles. Furthermore, the incorporation of CNC enhanced the thermal stability of these membranes while preserving the favorable mechanical properties of the KGM-based material. These findings highlight a straightforward approach to enhance the antibacterial properties of natural polymers, which can be effectively useful in medical devices like wound dressings that typically lack such properties.

Interplay of the Assembly Conditions on Drug Transport Mechanisms in Polyelectrolyte Multilayer Films.

The layer-by-layer film deposition is a suitable strategy for the design and functionalization of drug carriers with superior performance, which still lacks information describing the influence of assembly conditions on the mechanisms governing the drug release process. Herein, traditional poly(acrylic acid)/poly(allylamine) polyelectrolyte multilayers (PEM) were explored as a platform to study the influence of the assembly conditions such as pH, drug loading method, and capping layer deposition on the mechanisms that control the release of calcein, the chosen model drug, from PEM. Films with 20-40 bilayers were assembled at pH 4.5 or 8.8, and the drug loading process was carried out during- or post-film assembly. Release data were fitted to three release models, namely, Higuchi, Ritger-Peppas, and Berens-Hopfenberg, to investigate the mechanism governing the drug transport, such as the apparent diffusion and the relaxation time. The postassembly drug loading method leads to a higher drug loading capacity than the during-assembly method, attributed to the washing out of calcein during film assembly steps in the latter method. Higuchi's and Ritger-Peppas' model analyses indicate that the release kinetic constant increased with the number of bilayers for the postassembly method. The opposite trend is observed for the during-assembly method. The Berens-Hopfenberg release model enabled the decoupling of each drug transport mechanism's contribution, indicating the increase of the diffusion contribution with the number of bilayers for the postassembly method at pH 4.5 and the increase of the polymer relaxation contribution for the during-assembly method at pH 8.8. Deborah's number, which represents the ratio of the polymer relaxation time to the diffusion time, follows the trends observed for the relaxation contribution for the conditions investigated. The deposition of the capping phospholipid layer over the payload also favored the polymer relaxation contribution in the drug release, featuring new strategies to investigate the drug release in PEM.