Аннотация:Bioactive biodegradable chitosan films containing chitin nanofibrils have been developedfor use as face masks in cosmetology. It was found that thermal modification of chitosan filmspromotes the transformation of the polymer into insoluble form without the use of alkali or aldehydes.The structure and properties of the films were studied by IT spectroscopy, atomic force microscopy,thermogravimetric analysis, and X-ray structural analysis. Analysis of infrared (IR) spectra showedthat the addition of nanofibrils accelerates the process of thermal transformation in the compositefilms. This is apparent from the observed increase in the intensity ratio of 1030 cm−1\1580 cm−1peaks in the spectrum of the thermally treated film (as compared to the spectrum of the initialsample and the spectrum of a chitosan film without chitin nanofibrils). The prepared compositefilms containing chitin nanofibrils possess improved mechanical characteristics: tensile strength 99MPa and tensile strain 14%. The tetrazolium bromide (MTT) test revealed good viability of humandermal fibroblasts cultivated in the presence of the conditioned medium obtained after incubationof all types of films in the nutrient medium. The used process of thermal modification of chitosanand composite films (which is efficient and environmentally safe) allows one to prepare bioactivematerials for applications in medicine and cosmetology.