**4. Conclusions**

Environmentally safe hybrid hydrogel films with antibacterial properties were received based on hydroxypropyl methylcellulose modified with humic acids.

Using IR spectroscopy, it was determined that the hydroxypropyl methylcellulose, modified with humic acids, are received by the mechanism of matrix synthesis, which is accompanied by the crosslinking of hydroxypropyl methylcellulose through a multipoint interaction with the carboxyl group in humic acids.

Environmentally safe hybrid hydrogel films based on hydroxypropyl methylcellulose with humic acids (15% wt. content) exhibit antibacterial properties, which are achieved due to the complete inhibition of mold formation, sufficiently high levels of absorption, and the gelation time, which are ensured due to additional supramolecular multipoint interactions occurring between functional groups in addition to hydrogen bonds. The obtained environmentally safe biodegradable hydrogel films with bactericidal properties based on hydroxypropyl methylcellulose and humic substances appear to be promising in terms of their operational characteristics for the preparation of transdermal delivery systems for biologically active substances.

**Author Contributions:** Conceptualization, D.M.; methodology, A.C.; validation, A.C., V.L. and D.M.; formal analysis, K.L.; investigation, K.L.; resources, O.T.; data curation, N.K.; writing—original draft preparation, D.M. and V.L.; writing—review, and editing, D.M. and V.L.; visualization, K.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
