colors and styles. as antimicrobial technology develops at a rapid pace, these scrubs are readily available, with more advanced versions hitting the market every year. these bacteria could then be spread to office desks, break rooms, computers, and other shared technology. this can lead to outbreaks and infections like mrsa, treatments for which cost the healthcare industry $20 billion a year. halogens elements such as chlorine, iodine, fluorine, and bromine are nonmetallic in nature and constitute the halogen family. each of these halogens have a different antimicrobial effect that is influenced by various factors such as ph, temperature, contact time, and type of microorganism. chlorine and iodine are the two most commonly used antimicrobials. chlorine is extensively used as a disinfectant in the water treatment plants, drug, and food industries. in wastewater treatment plants, chlorine is widely used as a disinfectant. it oxidizes soluble contaminants and kills bacteria and viruses. it is also highly effective against bacterial spores. the mode of action is by breaking the bonds present in these microorganisms. when a bacterial enzyme comes in contact with a compound containing chlorine, the hydrogen atom in that molecule gets displaced and is replaced with chlorine. this thus changes the enzyme function which in turn leads to the death of the bacterium. iodine is most commonly used for sterilization and wound cleaning. the three major antimicrobial compounds containing iodine are alcohol-iodine solution, an aqueous solution of iodine, and iodophors. iodophors are more bactericidal and are used as antiseptics as they are less irritating when applied to the skin. bacterial spores on the other hand cannot be killed by iodine, but they can be inhibited by iodophors. the growth of microorganisms is inhibited when iodine penetrates into the cells and oxidizes proteins, genetic material, and fatty acids. bromine is also an effective antimicrobial that is used in water treatment plants. when mixed with chlorine it is highly effective against bacterial spores such as s. faecalis. alcohols alcohols are commonly used as disinfectants and antiseptics. alcohols kill vegetative bacteria, most viruses and fungi. ethyl alcohol, n-propanol and isopropyl alcohol are the most commonly used antimicrobial agents. methanol is also a disinfecting agent but is not generally used as it is highly poisonous. escherichia coli, salmonella, and staphylococcus aureus are a few bacteria whose growth can be inhibited by alcohols. alcohols have a high efficiency against enveloped viruses (60–70% ethyl alcohol) 70% isopropyl alcohol or ethanol are highly effective as an antimicrobial agent. in the presence of water, 70% alcohol causes coagulation of the proteins thus inhibiting microbial growth. alcohols are not quite efficient when it comes to spores. the mode of action is by denaturing the proteins. alcohols interfere with the hydrogen bonds present in the protein structure. alcohols also dissolve the lipid membranes that are present in microorganisms. disruption of the cell membrane is another property of alcohols that aid in cell death. alcohols are cheap and effective antimicrobials. they are widely used in the pharmaceutical industry. alcohols are commonly used in hand sanitizers, antiseptics, and disinfectants. phenol and phenolic compounds phenol also known as carbolic acid was one of the first chemicals which was used as an antimicrobial agent. it has high antiseptic properties. it is bacteriostatic at concentrations of 0.1%–1% and is bactericidal/fungicidal at 1%–2%. a 5% solution kills anthrax spores in 48 hr. phenols are most commonly used in oral mouth washes and household cleaning agents. they are active against a wide range of bacteria, fungi and viruses. today phenol derivatives such as thymol and cresol are used because they are less toxic compared to phenol. these phenolic compounds have a benzene ring along with the –oh group incorporated into their structures. they have a higher antimicrobial activity. these compounds inhibit microbial growth by precipitating proteins which lead to their denaturation and by penetrating into the cell membrane of microorganisms and disrupting it. phenolic compounds can also deactivate enzymes and damage the amino acids in microbial cells. phenolics such as fentichlore, an antibacterial and antifungal agent are used as an oral treatment for fungal infections. trischlosan is highly effective against both gram-positive and gram-negative bacteria. hexachlorophene (bisphenol) is used as a surfactant. it is widely used in soaps, handwashes, and skin products because of its antiseptic properties. it is also used as a sterilizing agent. cresol is an effective antimicrobial and is widely used in mouthwashes and cough drops. phenolics have high antimicrobial activity against bacteria such as staphylococcus epidermidis and pseudomonas aeruginosa. 2-phenylphenol-water solutions are used in immersion treatments of fruit for packing. (it is not used on the packing materials however.) ihloff and kalitzki 1961 find a small but measurable amount remains in the skin of fruits processed in this manner.: 193 aldehydes they are highly effective against bacteria, fungi and viruses. aldehydes inhibit bacterial growth by disrupting the outer membrane. they are used in the disinfection and sterilization of surgical instruments. being highly toxic they are not used in antiseptics. currently, only three aldehyde compounds are of widespread practical use as disinfectant biocides, namely glutaraldehyde, formaldehyde, and ortho-phthalaldehyde (opa) despite the demonstration that many other aldehydes possess good antimicrobial activity. however, due to its long contact time other disinfectants are commonly preferred. physical heat main articles: dry heat sterilization and moist heat sterilization microorganisms have a minimum temperature, an optimum, and a maximum temperature for growth. high temperature as well as low temperatures are used as physical agents of control. different organisms show different degrees of resistance or susceptibility to heat or temperature, some organisms such as bacterial endospore are more resistant while vegetative cells are less resistant and are easily killed at lower temperatures. another method that involves the use of heat to kill microorganisms is fractional sterilization. this process involves the exposure to a temperature of 100 degrees celsius for an hour, on each for several days. fractional sterilization is also called tyndallization. bacterial endospores can be killed using this method. both dry and moist heat are effective in eliminating microbial life. for example, jars used to store preserves such as jam can be sterilized by heating them in a conventional oven. heat is also used in pasteurization, a method for slowing the spoilage of foods such as milk, cheese, juices, wines and vinegar. such products are heated to a certain temperature for a set period of time, which greatly reduces the number of harmful microorganisms. low temperature is also used to inhibit microbial activity by slowing down microbial metabolism. radiation foods are often irradiated to kill harmful pathogens. there are two types of radiations that are used to inhibit the growth of microorganisms – ionizing and non-ionizing radiations. common sources of radiation used in food sterilization include cobalt-60 (a gamma emitter), electron beams and x-rays. ultraviolet light is also used to disinfect drinking water, both in small-scale personal-use systems and larger-scale community water purification systems. desiccation desiccation is also known as dehydration. it is the state of extreme dryness or the process of extreme drying. some microorganisms like bacteria, yeasts and molds require water for their growth. desiccation dries up the water content thus inhibiting microbial growth. on the availability of water, the bacteria resume their growth, thus desiccation does not completely inhibit bacterial growth. the instrument used to carry out this process is called a desiccator. this process is widely used in the food industry and is an efficient method for food preservation. desiccation is also largely used in the pharmaceutical industry to store vaccines and other products. antimicrobial surfaces antimicrobial surfaces are designed to either inhibit the ability of microorganisms to grow or damaging them by chemical (copper toxicity) or physical processes (micro/nano-pillars to rupture cell walls). these surfaces are especially important for the healthcare industry. designing effective antimicrobial surfaces demands an in-depth understanding of the initial microbe-surface adhesion mechanisms. molecular dynamics simulation and time-lapse imaging are typically used to investigate these mechanisms. osmotic pressure osmotic pressure is the pressure required to prevent a solvent from passing from a region of high concentration to a region of low concentration through a semipermeable membrane. when the concentration of dissolved materials or solute is higher inside the cell than it is outside, the cell is said to be in a hypotonic environment and water will flow into the cell.when the bacteria is placed in hypertonic solution, it causes plasmolysis or cell shrinking, similarly in hypotonic solution, bacteria undergoes plasmotysis or turgid state. this plasmolysis and plasmotysis kills bacteria because it causes change in osmotic pressure.