Alcohol-Based Hand Sanitizers: Relevance of the Physicochemical Properties of Alcohol-Water Mixtures

Abstract

The use of alcohol-water mixtures as antimicrobial agents for hand-hygiene grew significantly in the year 2020 due to the global  COVID-19 pandemic. Combining alcohols, such as ethanol or isopropanol, with water results in mixtures with a number of unusual characteristics with several solution properties deviating from ideal behavior. These characteristics are related to clustering or  aggregation of the constituent molecules at the microscopic level. This paper reviews the physicochemical properties (polarity, density, viscosity, vapor pressure, surface tension) of alcohol-water mixtures and their relevance to alcohol-based hand sanitizers. The role of the  quasi-surfactant characteristics (amphiphilism, surface and interfacial tension lowering) of alcohols in eliciting their antimicrobial effects  is discussed.