Hydrogels in Hand Sanitizers

Abstract

Hand hygiene can be considered a strategic key useful in the containment of infections such as COVID-19 both at home and in communities because it can dramatically reduce the widespread outbreak of infections. In case of the unavailability of soap and water, "instant" hand sanitizers are recommended because their application can be considered easy, versatile, quick and often less aggressive for the skin. For these reasons, alcoholic and alcohol-free hand rub gels can be considered the best performing formulations on the market. Together with disinfectants and antiseptic agents, hydrogels play a fundamental role in obtaining stable formulations and are easy to disperse, with a pleasant skin feel and an overall good performance. Several compounds commonly used in the pharmaceutical, cosmetic and food industry are available for this purpose, in particular, cellulose derivatives and synthetic polymers derivatives. Each of them is available in several grades, presenting different thickening behavior, rheological properties and compatibility with other ingredients, alcohols in particular. For all these reasons, it is important to explore hydrogel properties and behaviors in different contexts (i.e., hydroalcoholic and aqueous media) in order to develop new and performing hand rub gels, always taking into account the different international legal frameworks regarding disinfectant and sanitizing formulations.

Keywords: disinfectants; hand rub sanitizers; hydrogel.

Figure 1

Main differences and similarities between bacteria and viruses [45,46].

Figure 2

Most common antiseptic agents and excipients used in alcoholic sanitizing hand rubs (ABR) and alcohol-free sanitizing hand rubs (AFR). Hydrogels can be used to enhance the performance of both the sanitizing systems.

Figure 3

Histogram showing the increasing number of publications for the term “hydrogel” in the PubMed database.

Figure 4

Testing methods applied to assess mechanical properties of hydrogels: tensile testing (a), unconfined compression testing (b), confined compression test (c), and indentation testing (d).