Chitosan is a cationic natural polysaccharide, which has emerged as an increasingly interesting biomaterialover the past few years. It constitutes a novel perspective in drug delivery systems and nanocarriers’ formulations due to its beneficial properties, including biocompatibility, biodegradability and low toxicity. The potentiality of chemical or enzymatic modifications of the biopolymer, as well as its complementary use with other polymers, further attract the scientific community, offering improved and combined properties in the final materials. As a result, chitosan has been extensively used as a matrix for the encapsulation of several valuable compounds. In this review article, the advantageous character of chitosan as a matrix for nanosystemsis presented, focusing on the encapsulation of natural products. A five-year literature review is attempted covering the use of chitosan and modified chitosan as matrices and coatings for the encapsulation of natural extracts, essential oils or pure naturally occurring bioactive compounds are discussed.

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In this work, neoteric and biodegradable ionic liquids (ILs) based on various hydroxyl ammonium cations and formic acid anion have been used as media for biocatalytic oxidoreductions catalyzed by different metalloproteins. The effect of these ILs on the biocatalytic behavior and structure of solubilized enzymes was investigated using cytochrome c (cyt c) as a model protein. The use of ILs-based media enhances the tolerance of cyt c against the denaturing effect of H 2 O 2 and increases (up to 20 fold) its catalytic efficiency compared to that observed in buffer. This beneficial effect strongly correlates with the concentration of ILs used, as well as the chaotropicity of their cations. UV-vis, circular dichroism and Fourier transform infrared (FT-IR) spectroscopic studies indicated that, the effect of ILs on the catalytic behavior of cyt c could be correlated with slight structural changes on the protein molecule and/or perturbations of the heme microenvironment. The use of hydroxyl ammonium-based ILs as reaction media increased (up to 4-fold) the decolorization activity of cyt c. All ILs used were recycled and successfully reused three times indicating the potential application of these novel ILs as environmentally friendly media for biocatalytic processes of industrial interest. Ionic liquids (ILs), also called molten salts, are 2 mixtures of cations and anions that melt below 100 o C and 3 have received considerable attention over the last decade as an 4 environmentally friendly alternative to organic solvents. Due to 5 their interesting physical and chemical properties, such as 6 negligible vapour pressure, ability to dissolve various 7 hydrophobic/hydrophilic compounds and excellent chemical 8 and thermal stability, they have been widely used as "green" 9 media for biocatalytic processes. 1-3 The first studies of enzyme-10 catalyzed reactions in ILs were reported in so called second 11 generation ILs, which are mainly based on cations of 12 heterogeneous cyclic amines, such as substituted imidazoliums 13 and alkyl pyridiniums, as well as poor nucleophilic anions, 15 In the last years, numerous studies of second 16 generation ILs, in the context of biocatalysis, revealed that 17 many enzymes exhibit excellent selectivity and activity and 18 maintain very high thermal and operational stability in these 19 solvents. 6-12 However, their use in large scale applications is 20 limited due to their difficult preparation and high cost. 1 21 Moreover, concerns have arisen regarding the environmental 42 combination of a Brønsted acid with a Brønsted base. 22,28 43 Furthermore, both cation and anion exhibit a considerably low

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In the frame of research that examines the use of task-specific ionic liquids (ILs) for developing green methodologies toward novel bioactive compounds, ethanolamine-derived ILs were synthesized and used as solvents and catalysts in a domino Knoevenagel−Michael reaction. After extended optimization studies regarding the most important reaction parameters such as reaction time, temperature, and molar ratio of reactants, it was ascertained that the reaction between 4-hydroxy-coumarin and various benzaldehydes in the synthesized ILs proceeded smoothly at 40 °C in 3 h, providing the desired biscoumarins in very satisfactory yields (up to 97%) and high purity after simple workup. The task-specific ILs were recycled and reused three times without a noticeable decrease in their catalytic activity. Moreover, the biodegradability potential of the synthesized ILs has been investigated by applying the biological oxygen demand (BOD-5) closed bottle test. The results indicated that organic carbon was biodegraded up to 59% within five days.