Background: Multiple strategies have been recommended for prevention and control of antibacterial resistance. Solutions will need to be found soon if we are not to run the serious risk of losing the ability to treat bacterial infections, especially the ones arising from multi-resistant strains. Deep knowledge of the resistance mechanisms followed by novel therapeutic drugs and vaccines are needed. A consolidated, multidisciplinary and regulated strategy is required by this challenge. Objective: This review will be focused on new strategies to control infections. Among strategies to tackle antibiotic resistance that have been under investigation, are the use of antimicrobial peptides, phage therapy and phage enzymes, therapeutic antibodies, quorum sensing inhibitors and, finally, the antibacterial nanomedicines. Although all of the approaches seem to be effective, and at least one of them has been in use for relatively a long time (phage therapy), antibacterial nanomedicines show the most diverse range of different approaches regarding potential translation to clinics. Results & Conclusion: Several advances have been made but a great effort is still mandatory in order to reach feasible, effective and marketable novel antimicrobial products.

Cellulose, the most abundant natural polymer on earth, is used in numerous applications in our day-to-day life. However, the discovery that cellulose-based systems could lead to the formation of liquid crystalline phases only dates to the 1970s. Compared with all known applications of cellulose, the liquid crystalline behavior has been less considered. Associated with this are the low solubility of cellulose and the existence of a chiral nematic precursor solution and its processing under the action of a shear field, which is used to produce fibers and films. In this review, we first conduct a short review of the main features of cellulosic liquid crystalline phases including the main textures observed by polarizing optical microscopy and the cholesteric phase characteristics of thermotropic and lyotropic systems observed for cellulose and cellulose derivatives. Then, we focus on the rheological properties of liquid crystalline solutions and special attention is given to the formation of striations developed during shear and the formation of the band texture, which appears during the relaxation process. Among the different techniques used, special emphasis is given to the results obtained by coupling rheology with optical microscopy (Rheo-optics) and nuclear magnetic resonance (Rheo-NMR) techniques. Some examples described in the literature, related to the use of cellulose and cellulose derivatives liquid crystals to the production of structural color scaffolds, stimuli-responsive films and fibers, are addressed. In these systems, the initial cholesteric phase determines the unique properties exhibited by the films and the fibers produced from cellulosic liquid crystalline systems.

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.

Infections associated with the surfaces of medical devices represent a critical problem due to biofilm formation and the growing resistance towards antibacterial drugs. This is particularly relevant in commonly used invasive devices such as silicone-based ones where a demand for alternative antibiofilm surfaces is increasing. In this work, an antimicrobial chitosan-biosurfactant hydrogel mesh was produced by 3D-printing. The 3D structure was designed to coat polydimethylsiloxane-based medical devices for infection prevention. Additionally, the porous 3D structure allows the incorporation of customized bioactive components. For this purpose, two biosurfactants (surfactin and sophorolipids) were biosynthesized and tested for their antimicrobial activity. In addition, the printing of surfactant-chitosan-based coatings was optimized, and the resulting 3D structures were characterized (i.e., wettability, FTIR-ATR, antimicrobial activity, and biocompatibility). Compared with surfactin, the results showed a better yield and higher antibacterial activity against Gram-positive bacteria for sophorolipids (SLs). Thus, SLs were used to produce chitosan-based 3D-printed coatings. Overall, the SLs-impregnated coatings showed the best antibacterial activity against Staphylococcus aureus planktonic bacteria (61 % of growth inhibition) and antibiofilm activity (2 log units reduction) when compared to control. Furthermore, concerning biocompatibility, the coatings were cytocompatible towards human dermal fibroblasts. Finally, the coating presented a mesh suitable to be filled with a model bioactive compound (i.e., hyaluronic acid), paving the way to be used for customized therapeutics.

This paper proposes a multifunctional soft robotic gripper for a Dobot robot to handle sensitive products. The gripper is based on pneumatic network (PneuNet) bending actuators. In this study, two different models of PneuNet actuators have been studied, designed, simulated, experimentally tested, and validated using two different techniques (3D printing and molding) and three different materials: FilaFlex 60A (3D-printed), Elastosil M4601, and Dragonskin Fast 10 silicones (with molds). A new soft gripper design for the Dobot robot is presented, and a new design/production approach with molds is proposed to obtain the gripper’s PneuNet multifunctional actuators. It also describes a new control approach that is used to control the PneuNet actuators and gripper function, using compressed air generated by a small compressor/air pump, a pressure sensor, a mini valve, etc., and executing on a low-cost controller board—Arduino UNO. This paper presents the main simulation and experimental results of this research study.

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.