A new photonic structure is produced from cellulose nanocrystal iridescent films reflecting both right and left circularly polarized light. Micrometer‐scale planar gaps perpendicular to the films' cross‐section between two different left‐handed films' cholesteric domains are impregnated with a nematic liquid crystal. This photonic feature is reversibly tuned by the application of an electric field or a temperature variation.
Urinary and intravascular catheters
are two of the most used invasive
medical devices; however, microbial colonization of catheter surfaces
is responsible for most healthcare-associated infections (HAIs). Several
antimicrobial-coated catheters are available, but recurrent antibiotic
therapy can decrease their potential activity against resistant bacterial
strains. The aim of this Review is to question the actual effectiveness
of currently used (coated) catheters and describe the progress and
promise of alternative antimicrobial coatings. Different strategies
have been reviewed with the common goal of preventing biofilm formation
on catheters, including release-based approaches using antibiotics,
antiseptics, nitric oxide, 5-fluorouracil, and silver as well as contact-killing
approaches employing quaternary ammonium compounds, chitosan, antimicrobial
peptides, and enzymes. All of these strategies have given proof of
antimicrobial efficacy by modifying the physiology of pathogens or
disrupting their structural integrity. The aim for synergistic approaches
using multitarget processes and the combination of both antifouling
and bactericidal properties holds potential for the near future. Despite
intensive research in biofilm preventive strategies, laboratorial
studies still present some limitations since experimental conditions
usually are not the same and also differ from biological conditions
encountered when the catheter is inserted in the human body. Consequently,
in most cases, the efficacy data obtained from in vitro studies is not properly reflected in the clinical setting. Thus,
further well-designed clinical trials and additional cytotoxicity
studies are needed to prove the efficacy and safety of the developed
antimicrobial strategies in the prevention of biofilm formation at
catheter surfaces.
Several advances have been made but a great effort is still mandatory in order to reach feasible, effective and marketable novel antimicrobial products.
Cellulose nanocrystals are isolated from plant cellulose structures, e.g., cotton. In article 1603560, M. H. Godinho and co‐workers describe a tunable photonic material produced from these cellulose nanocrystals iridescent films, which reflects both right‐ and left‐handed circularly polarized light, taking advantage of the gaps existing along the cellulose nanocrystals films that are filled with a nematic liquid crystal.
Chitosan is an interesting polymer to produce hydrogels suitable for the 3D printing of customized drug delivery systems. This study aimed at the achievement of chitosan-based scaffolds suitable for the incorporation of active components in the matrix or loaded into the pores. Several scaffolds were printed using different chitosan-based hydrogels. To understand which parameters would have a greater impact on printability, an optimization study was conducted. The scaffolds with the highest printability were obtained with a chitosan hydrogel at 2.5 wt%, a flow speed of 0.15 mm/s and a layer height of 0.41 mm. To improve the chitosan hydrogel printability, starch was added, and a design of experiments with three factors and two responses was carried out to find out the optimal starch supplementation. It was possible to conclude that the addition of starch (13 wt%) to the chitosan hydrogel improved the structural characteristics of the chitosan-based scaffolds. These scaffolds showed potential to be tested in the future as drug-delivery systems.
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