Which of the following sterilisation methods achieves sterilisation by disrupting microbial cell membranes through the generation of reactive oxygen species?

Explanation

## Hydrogen Peroxide Gas Plasma Sterilisation **Key Point:** Hydrogen peroxide gas plasma (H₂O₂ gas plasma) sterilisation works by generating reactive oxygen species (ROS) that damage microbial cell membranes, DNA, and proteins, leading to cell death. ### Mechanism of Action The sterilisation process involves: 1. **Plasma generation**: Low-temperature plasma is created from hydrogen peroxide vapour 2. **ROS production**: The plasma generates free radicals and reactive oxygen species 3. **Cellular damage**: ROS penetrate and disrupt microbial cell membranes and nucleic acids 4. **Breakdown products**: Final products are water and oxygen — non-toxic residues ### Key Characteristics | Feature | H₂O₂ Gas Plasma | Ethylene Oxide | Dry Heat | | --- | --- | --- | --- | | **Temperature** | 37–50°C (low) | 37–60°C (low) | 160–180°C (high) | | **Mechanism** | ROS generation | Alkylation | Protein denaturation | | **Penetration** | Moderate | Excellent | Poor | | **Residue** | Water + O₂ | Ethylene glycol (toxic) | None | | **Material compatibility** | Good for electronics | Good for plastics | Damages heat-sensitive items | **High-Yield:** H₂O₂ gas plasma is the preferred method for heat- and moisture-sensitive medical devices (endoscopes, electronic equipment) because it operates at low temperature and leaves no toxic residue. **Clinical Pearl:** Unlike ethylene oxide, H₂O₂ gas plasma does not require lengthy aeration periods post-sterilisation, making it faster and safer for hospital use. ### Why H₂O₂ Gas Plasma? The question specifically asks about **disruption of microbial cell membranes through ROS generation**. This is the defining mechanism of H₂O₂ gas plasma sterilisation — it is the only method listed that works primarily through oxidative stress and free radical damage.