Kinetics of Low Temperature Polyester Dyeing with High Molecular Weight Disperse Dyes by Solvent Microemulsion and AgroSourced Auxiliaries.

This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the effect of two non-toxic agro-sourced auxiliaries (o-vanillin and coumarin) using a non-toxic organic solvent. A dyeing bath consisting of a micro-emulsion system involving a small proportion of n-butyl acetate was used, and the kinetics of dyeing were analysed at four temperatures (83, 90, 95 and 100 °C). Moreover, the dyeing rate constants, correlation coefficient and activation energies were proposed for this system. It was found that o-vanillin yielded higher dye absorption levels than coumarin, leading to exhaustions of 88% and 87% for Disperse Red 167 and Disperse Blue 79, respectively. K/S values of dyed polyester were also found to be higher for dye baths containing o-vanillin with respect to the ones with coumarin. In terms of hot pressing fastness and wash fastness, generally no adverse influence on fastness properties was reported, while o-vanillin showed slightly better results compared to coumarin.

Sonochemically processed cationic nanocapsules: efficient antimicrobials with membrane disturbing capacity.

Bacterial-mediated diseases are a major healthcare concern worldwide due to the rapid spread of antibiotic-resistant bacteria. One strategy to manage the bacterial infections while avoiding the emergence of resistant strains implies specific targeting and disruption of bacteria membranes. This work evaluates the potential of nanostructured biopolymer derivatives, nanocapsules (NCs), to disrupt the bacteria cell walls and effectively kill planktonic microorganisms. Two biopolymers, chitosan and cellulose, were chemically modified to synthesize derivatives with improved cationic character (thiolated chitosan and aminocellulose) prior to their processing into nanocapsules via a one-step sonochemical process. The interactions of NCs, displaying an average size of around 250 nm, with bacteria membrane were evaluated using two membrane models: Langmuir monolayers and liposome bilayers composed of a l-α-phosphatidylglycerol phospholipid extracted from Escherichia coli. NCs possessed improved membrane disturbing capacity in comparison to the nonprocessed biopolymer derivatives, by drastically increasing the monolayer fluidity and inducing more than 50% leakage of a dye inserted in the bilayered liposomes. In addition, membrane disturbance was directly proportional to the NCs cationic charge. Whereas evidence showed that thiolated chitosan and aminocellulose interacted with the bacteria membrane through a "carpet model", the NCs were found to induce larger surface defects and high local perturbance through a "detergent model". Importantly, the degree of disruption caused by the biopolymer derivatives and NCs correlated well with the antimicrobial capacity against Escherichia coli, selectively killing bacteria cells without imparting toxicity to human fibroblasts.