(36b) Spray-Dried Powder Hand Sanitiser with a Long-Lasting Effect

Pathogens are spread by contact from person to person, e.g., by handshakes, or indirectly through contaminated surfaces. One way to limit transmission is to keep our hands clean, which is achieved by standard hygiene habits with additional usage of various ethanol-based disinfectants, which became more frequent with the Covid-19 pandemic situation in the last couple of years. However, when access to running water is limited or during long-lasting activities (e.g., surgical procedures, rescue operations), dry powder sanitisers activated by human sweat may find their practical use. Although hand disinfectants and sanitizers have a great immediate effect, they do not provide long-term protection once they dry off the skin. Another aspect is that repeated use of some products (typically alcohol-based) may cause skin irritation or eventually more severe health problems. Therefore, the goal of this work is to create a hand sanitiser with a gradual release of the active ingredient, which would provide protection against microorganisms lasting tens of minutes to hours.

For this purpose, we introduce micron-sized particles, which are retained at the papillary lines of our hands after application with a gradual release of the active component(s). The suitability of chitosan microparticles with incorporated active compound chlorhexidine, and with varying degrees of cross-linking have been investigated. The morphology, particle size distribution, and release rate of the chlorhexidine were compared, and selected particles were further tested on microorganisms (E. coli and S. epidermidis) for immediate and prolonged effects. Particle deposition, adhesion, and abrasion resistance will be tested on a human finger replica, simulating topographical features and characteristics of the skin.