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  • Writer's pictureNaomi Roach

The Science Behind Hand Sanitisers: How Do They Work?

In the battle against germs and infectious diseases, hand sanitiser has emerged as a powerful ally, especially in situations where soap and water are not readily available. This (often) alcohol-based solution, offers a quick and convenient way to disinfect hands, but have you ever wondered how they work at a molecular level? In this blog post, we will explore the science behind hand sanitiser, understanding the mode of action and key ingredients making them effective in killing harmful microbes.

  1. The Active Ingredients: Most hand sanitiser contains alcohol as the primary active ingredient. Ethanol (ethyl alcohol) and isopropanol (isopropyl alcohol) are the two most common types of alcohol used. Alcohol is highly effective in killing or deactivating a broad spectrum of microorganisms, including bacteria, viruses, and fungi. Its antimicrobial properties disrupt the outer membranes of these pathogens, leading to their deactivation.

  2. Disruption of Cell Membranes: Upon application, alcohol-based hand sanitisers come into contact with the microorganisms present on our skin. These pathogens have lipid-based cell membranes that encase their genetic material and other essential components. Alcohol is known to be a lipid solvent, and when it comes into contact with the cell membrane, it starts to dissolve the lipids, breaking down the structure of the membrane.

  3. Protein Denaturation: Apart from targeting the cell membrane, alcohol also interacts with proteins within the microorganisms. Proteins are essential for the proper functioning and survival of any living cell. Alcohol disrupts the protein structure through a process called denaturation. It unfolds and distorts the protein's shape, rendering it non-functional. As a result, vital enzymes and proteins that support the microorganism's survival are no longer able to perform their roles, leading to their inactivation.

  4. Rapid Evaporation and Contact Time: The effectiveness of hand sanitisers is influenced by their alcohol concentration and the duration of contact with the pathogens. Hand sanitiser typically contains between 60% to 95% alcohol. When applied to the skin, the alcohol rapidly evaporates, making it important to maintain contact with the skin for at least 20 to 30 seconds. This duration allows enough time for the alcohol to work on the pathogens and achieve optimal germ-killing or destroying results.

  5. Limitations: While hand sanitiser is effective in many situations, it's essential to recognise their limitations. They are not as effective when hands are visibly dirty or greasy, as the dirt or oil can shield the pathogens from the alcohol. In such cases, traditional handwashing with soap and water is more appropriate. Additionally, hand sanitiser may not be effective against certain types of viruses with tougher outer shells, such as the norovirus, so while using it when handwashing is not an option is a great backup, it's always good to maintain ensure hands are washed regularly throughout the day.

Conclusion: Hand sanitisers are a powerful tool in our fight against germs, bacteria, viruses, and fungi. Their ability to disrupt the lipid membranes and denature proteins of microorganisms is what makes them highly effective in killing harmful pathogens. However, it is crucial to use hand sanitisers correctly and understand their limitations. In situations where handwashing facilities are not available or when used in conjunction with proper hand hygiene practices, hand sanitisers play a significant role in maintaining personal and public health. Remember, clean hands save lives!

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