Nevertheless, the public users must pay attention to the shelf-life of solution B to ensure the quality of the hand-sprayer coating. We further attempt to extend the generality of the antibacterial coatings on various high-risk surfaces in public places and healthcare facilities, including rubber handrails of escalators (Figure ), stainless steel objects (e.g. kitchenware, doorknobs, etc., Figure ), and finger-touch switches (e.g. light switch, elevator control panels, Figure ). These three examples were chosen to represent three typical categories of materials (i.e. rubbers, metals, and plastics), widely used for all kinds of hand-touch surfaces in our modern civilization.