Films or coatings: Films occlude microbial access to surfaces, preventing their adherence, preventing biofilm formation, and killing bacteria. Hospitals are high traffic areas with objects and surfaces being handled/touched by many people, making them foci of disease spread. Antibacterial copper nanoparticle-containing coatings have been suggested for application to surfaces in hospitals such as bed rails and chairs to reduce the viability of bacteria and viruses on those surfaces. For example, poly(ethylene glycol diacrylate) films containing copper nanoparticles were prepared as antibacterial films. Catheters and intravenous lines are also common sources of infection; they carry bacteria from the environment into patients, bypassing the defenses of the skin and mucous membranes, and increasing the population of microbes in people of special concern in immuno-compromised individuals who have reduced energy or resources to fight off infection. Reducing the ability of medical devices to transmit infection would be an effective way to improve the health and survival of hospital patients. To this end, polycationic polymers (including quaternary ammonium saltcontaining polymers), zwitterions, poly(ethylene glycols), and antibacterial peptides are promising materials to be used as antibacterial coatings for preventing medical device associated infections. Flat surfaces can be used to harvest UV and visible light and use it to generate reactive species such as singlet oxygen. While ultraviolet light is lethal to many microbes, it is also harmful to human and animal cells, and so materials that can use visible light to generate reactive species are preferable. A photoactive polymer was prepared and shown to generate singlet oxygen, killing nearby cells. The anatase form of titanium dioxide generates reactive oxygen species upon irradiation which are toxic to microbial cells; 359 this activity also underlies the use of TiO2 in self-cleaning window coatings. Antimicrobial films may also serve other purposes. Antifouling coatings can be formed without the use of antimicrobial agents by the generation of superhydrophobic surfaces in which the feature sizes (on a micron or nanometer scale) and shapes prevent both water and other solvents from binding effectively to the surface. Surfaces that can repel water and other solvents can also prevent dirt and microorganisms from adhering to a surface. Superhydrophobic films can also be used on fabrics to repel water and dirt, to reduce their need for laundering, but previous coatings have used fluorinated polymers whose degradation products, intermediates, and precursors are persistent pollutants with unknown toxicities, deprecating their use. Antibacterial films can also be used to reduce bacterial degradation of food, reducing food waste. Edible films using chitosan, starches modified to improve their durability in the presence of water, carboxymethylcellulose and cyclodextrins, pectin, zein, whey protein, and the Maillard adducts of soy protein and carbohydrates have been tested for food preservation to preserve food while reducing fossil fuel use. 364