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The wastewater treatment, particularly the removal of organic contaminants, is often carried out by adsorption with solids. Hydrogels present a great swelling capacity that can be enhanced by the incorporation of nano-clays such as montmorillonita (Mt). Methylene blue is a common component of industrial effluents and its ecotoxicity in well-known. The aim of this work was to evaluate the adsorption capacity of hydrogels based on pectin and brea gum with Mt nanoparticles. The hydrogels were physically characterized, it was observed that Mt is exfoliated into the matrix, and affects the swelling and erosion of them. Incorporation of Mt caused an increment of swelling of approximately 150% at pH 6.5. The effects of various experimental parameters have been investigated. The temperature effect on the adsorption rate indicated an endothermic process with activation energy of 33.231 kJ mol−1. The removal % of MB at 45 °C, pH 2.5 and 75 mg L−1 of MB solution presented a value of 97%. The adsorption kinetic was analysed through different mathematical models (pseudo-first order, pseudo-second order, intra-particle, and Boyd models). Statistics and further analysis of the kinetics constants indicated that the pseudo-second order model better represents the behaviour of the samples. The application of intra particle model and Boyd model indicates that the adsorption phenomenon occurs in two stages. The first stage, of short duration, is related to the boundary layer. The second stage, which controls the process, is related to the chemical adsorption of the dye on the polymeric structure of the hydrogel.

Edible films based on fruit and vegetable purees combined with different food-grade biopolymeric binding agents (e.g., pectin, gelatin, starch, sodium alginate) are recognized as interesting packaging materials that benefit from the physical, mechanical, and barrier properties of biopolymers as well as the sensory and nutritional properties of purees. In the current contribution, edible antioxidant films based on pear juice and pregelatinized cassava starch were developed. In particular, the suitability of using pregelatinized cassava starch for the non-thermal production of these novel edible films was evaluated. In addition, the effects on the films’ properties derived from the use of pear juice instead of the complete puree, from the content of juice used, and from the carbohydrate composition associated with the ripening of pears were all studied. The produced films were characterized in terms of their total polyphenol content, water sensitivity, and water barrier, optical, mechanical and antioxidant properties. Results showed that the use of pear juice leads to films with enhanced transparency compared with puree-based films, and that juice concentration and carbohydrate composition associated with the degree of fruit ripeness strongly govern the films’ properties. Furthermore, the addition of pregelatinized cassava starch at room temperature discloses a significant and favorable impact on the cohesiveness, lightness, water resistance, and adhesiveness of the pear-juice-based films, which is mainly attributed to the effective interactions established between the starch macromolecules and the juice components.

Polyaniline nanoparticles (PANI-Nps) have been used in several applications; however, there are few publications related to the use in the photothermal therapy. PANI-Nps have high optical absorbance in the near-infrared region and in this wavelength range, biological systems are relatively transparent. For this reason, these materials can be used to absorb energy and to generate heat that destroys cancer cells selectively. PANI-Nps with average size of ca. 200 nm and neutral zeta potential were synthesized and characterized by DLS, SEM, and zeta potential. The kinetics of incorporation of PANI-Nps into LM2 cell line was monitored using UV–Vis spectrophotometry. The analysis of cell viability after PANI-Nps exposure shows that these nanoparticles are not cytotoxic even at high concentration and show no change in cell morphology and metabolic activity. Furthermore, we found that nanoparticle cell uptake reaches the maximum value c.a. 3 h after incubation. Cells were targeted by Pani-Nps and irradiated, resulting in significant elevation of intracellular ROS and heat production. One of the mechanisms of PANI-Nps-mediated photothermal killing of cancer cells apparently involved oxidative stress resulting in apoptotic cell death. Graphical Abstract