*Article* **Poly(chitosan-ester-ether-urethane) Hydrogels as Highly Controlled Genistein Release Systems**

**Martyna Zagórska-Dziok <sup>1</sup> , Patrycja Kleczkowska 2,3 , Ewa Ol˛edzka <sup>4</sup> , Ramona Figat <sup>5</sup> and Marcin Sobczak 1,4,\***


**Abstract:** Polymeric hydrogels play an increasingly important role in medicine, pharmacy and cosmetology. They appear to be one of the most promising groups of biomaterials due to their favorable physicochemical properties and biocompatibility. The objective of the presented study was to synthesize new poly(chitosan-ester-ether-urethane) hydrogels and to study the kinetic release of genistein (GEN) from these biomaterials. In view of the above, six non-toxic hydrogels were synthesized via the Ring-Opening Polymerization (ROP) and polyaddition processes. The poly(esterether) components of the hydrogels have been produced in the presence of the enzyme as a biocatalyst. In some cases, the in vitro release rate of GEN from the obtained hydrogels was characterized by near-zero-order kinetics, without "burst release" and with non-Fickian transport. It is important to note that developed hydrogels have been shown to possess the desired safety profile due to lack of cytotoxicity to skin cells (keratinocytes and fibroblasts). Taking into account the non-toxicity of hydrogels and the relatively highly controlled release profile of GEN, these results may provide fresh insight into polymeric hydrogels as an effective dermatological and/or cosmetological tool.

**Keywords:** active substance delivery systems; biomedical hydrogels; active substance-controlled release; genistein; hydrogels for cosmetology; hydrogels for dermatology; transdermal active substance delivery systems
