Infection is a major prompt of chronic wounds, increasing the pH on the injury tissues. Thus, pH can be used as trigger for antimicrobial agents’ delivery, preventing chronic wounds. Hence, the present work aimed to develop a hydrogel with drug delivery capacity, modulated by environmental pH. Chitosan was used as electrolyte monomer and it was crosslinked with hydroxypropyl methylcellulose and 2‐hydroxypropyl‐β‐cyclodextrin. The polymeric network assembly was confirmed by FTIR and thermal analysis. The developed hydrogels behaved as superabsorbent systems, with higher swelling at pH 7. Caffeic acid loading was ruled by the inclusion complex formation between the phenolic acid and cyclodextrin. Chitosan hydrogels delivery capacity was pH‐dependent and, also, more efficient at pH 7. Based on the Peppas–Sahlin model, fickian diffusion was the main mechanism responsible for caffeic acid release. Based on the results, the developed hydrogel can be used to prevent wound infection, due to its ability to release antimicrobial agents when the wound pH rises.

Thermoelectric (TE) devices that convert a heat gradient directly into electricity are considered as a clean technology for energy harvesting. Both hole-transporting (p-type) and electron-transporting (n-type) materials are required in order to fabricate a thermoelectric module. Carbon nanotube (CNT)-based textile fabrics are relevant in this context for the production of wearable TE modules due to the combination of the high electrical conductivity and thermopower (Seebeck coefficient) from the CNT and the low thermal conductivity and flexibility provided by the textile fabric [1]. Nevertheless, most as-produced CNTs are p-type materials due to their inherent oxygen doping, and therefore the production of air- and thermally stable n-type CNT-based textile fabrics remains a challenge nowadays [2]. On the other hand, vapor-grown carbon nanofibers (VGCNF), produced by chemical vapor deposition (CVD), have similar structures to multiwall carbon nanotubes (MWCNT), which make them valuable for electronic applications. For instance, by adjusting process variables during their CVD and post-growth heat treatment, VGCNF can be tailored to have a wide range of thermal conductivity and electrical conductivity at room temperature. In particular, the unexpected n-type character at room temperature that they supply to dip-coated cotton fabrics will be the issue of this presentation [3].

Essential oils (EOs) have been considered as a potential alternative to antibiotics in the treatment of several diseases, due to its antimicrobial properties. For instance, the tea tree essential oil (TTO), extracted from the Melaleuca alternifolia, has been reported to exhibit analgesic, antiviral, antibacterial, antifungal, antiprotozoal and anti-inflammatory properties. Likewise, the cinnamon leaf essential oil (CLO), has exhibited excellent antioxidant and antibacterial properties. However, one of the major drawbacks associated with the use of EOs in biomedical applications is their toxicity and the difficult control of EOs degradation and loss during manufacturing of the substrate. For this reason, recently, alternatives for the controlled release of EOs have been proposed, being the manufacturing of polymeric films loaded with nanocapsules highlighted. In this work, we report the nanoencapsulation of TTO and CLO using chitosan (CS), which is a polysaccharide that exhibits exceptional antibacterial features and is sensitive to the environment pH, for the subsequent functionalization of polymeric films. Cellulose acetate (CA) and polycaprolactone (PCL) at different ratios were processed in the form of wet-spun fibers, using acetone/acetic acid as solvent and ethanol as coagulation bath. TTO and CLO were diluted in etanol and presented to the fibers during production at the coagulation baths. The EOs presence in the fibers was detected visually by changes in the fibers' coloration. EO-loaded and unloaded fibers were characterized according to their chemical, mechanical and thermal properties and their degradation profile was followed in physiological media. The minimum inhibitory concentration of EOs and the antimicrobial action of the CA/PCL films were determined against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. Data reported the EOs-modified fibers to be successfully prepared and that the addition of the TTO and CLO to increase significantly the antimicrobial action of the polymers.