The paper reports new hydrogels based on quaternary ammonium salts of chitosan designed as biocidal products. The chitosan derivative was crosslinked with salicylaldehyde via reversible imine bonds and supramolecular selfassemble to give dynamic hydrogels which respond to environmental stimuli. The crosslinking mechanism was demonstrated by 1H NMR and FTIR spectroscopy, and X-ray diffraction and polarized light microscopy. The hydrogel nature, self-healing and thixotropy were proved by rheological investigation and visual observation, and their morphology was assessed by scanning electron microscopy. The relevant properties for application as biocidal products, such as swelling, dissolution, bioadhesiveness, antimicrobial activity and ex-vivo hemocompatibility and in vivo local toxicity and biocompatibility on experimental mice were measured and analyzed in relationship with the imination degree and the influence of each component. It was found that the hydrogels are superabsorbent, have good adhesivity to skin and various surfaces and antimicrobial activity against relevant gram-positive and gram-negative bacteria, while being hemocompatible and biocompatible. Besides, the hydrogels are easily biodegraded in soil. All these properties recommend the studied hydrogels as ecofriendly biocidal agents for living tissues and surfaces, but also open the perspectives of their use as platform for in vivo applications in tissue engineering, wound healing, or drug delivery systems.

Surfactants are used in agriculture as soil conditioners and components of fungicides, pesticides, and fertilizers. These materials are considered contaminants found in the soil. They can be absorbed by plants and animals and can impact human health when consumed. The objective of this study was to evaluate the phytotoxicity of four cationic surfactants: hexadecyl trimethyl ammonium bromide (HDTMA), octadecyl trimethyl ammonium chloride amine and amine in a hydroponic culture system of lettuce in doses of 0 to 10 mg/L. The variables evaluated were water consumption, dry biomass, leaf area, electrical conductivity (EC), and content of NO3-, K+, and Ca2+in the nutrient solution. After 40 days of exposure to DDA, this did not influence the dry biomass of the plant; however, the application of 1 mg/L of HDTMA decreased the biomass by 27 %, 46 % with 4 mg/L of OTAC, and 60 % with 4 mg/L of HDA. The decrease in water consumption by surfactants was 27 % with 1 mg/L of HDTMA, 20 % with OTAC, and 34 % with HDA from 2 mg/L, and the application of DDA did not show a reducing effect. In most of the variables, the DDA surfactant did not affect the response; in addition, the HDA surfactant was the second to cause the least damage to the crop because it does not have a toxic companion ion such as Cl and Br.