Gram-negative bacteria are less affected due to the hidden peptidoglycan layer beneath the membrane.
Ineffectiveness Against Viruses
Essential oils don't affect viruses as they target peptidoglycan, which viruses lack.
Halogens: Highly Reactive Elements
Halogens (fluorine, chlorine, bromine, iodine) are highly reactive due to having one available electron.
Most are toxic in their elemental form.
Iodine: A Medically Relevant Halogen
Iodine is the least reactive halogen and commonly used in medical settings.
It inhibits protein synthesis and alters plasma membrane permeability, causing thickness changes and leakage.
Tincture: Iodine dissolved in alcohol (common antiseptic).
Iodophore: Iodine dissolved in organic chemicals (ether), used as a surgical antiseptic but must be used carefully due to inhalation hazards.
Chlorine: A Basic Disinfectant
Chlorine is a fundamental disinfectant, acting as an aggressive oxidizer that disrupts cellular function at the enzymatic level.
Bleach (hypochlorous acid, HOCl) is the most common form.
Effective against most bacteria and viruses, but not non-enveloped viruses or endospores.
Chloramine: A Hazardous Sterilizing Agent
Chloramine (mustard gas) forms when chlorine and ammonia are mixed.
Medically, it sterilizes clean rooms by killing everything and allowing for a hyperbaric clean room environment.
Fluorine: Dental and Public Health Implications
Fluorine is rarely used in chemical control, except in toothpaste and water, to kill bacteria causing dental cavities, plaque, and tartar.
Potential removal of fluoride from US water supplies could lead to a dental health epidemic.
Alcohol: Denaturing Proteins and Dissolving Lipids
Alcohols denature proteins and dissolve lipids, damaging plasma membranes permanently.
Used to clean microscope slides by dissolving oil (a lipid).
Effective against lipid-enveloped viruses but not non-enveloped viruses or endospores.
Denatures the proteins, and dissolves the lipids
Considerations for High-Concentration Alcohols
Ethanol and isopropyl alcohol (IPA) are common; IPA for cleaning is not the same as beer.
High concentrations (e.g. 93% IPA) can cause blindness or liver failure if ingested; rubbing alcohol is usually around 5% to discourage ingestion.
93% Iso alcohol is alcohol dissolved in 7% water
Heavy Metals: Oligodynamic Activity
Heavy metals exhibit oligodynamic activity, interrupting microbial activity in small amounts.
Uranium, lead, plutonium, cadmium, and radon are toxic to bacteria but also toxic to humans.
Four microbially toxic metals safe for human-adjacent use: silver (Ag), mercury (Hg), copper (Cu), and zinc (Zn).
Mechanism of Heavy Metal Toxicity
These metals denature proteins, leading to metabolic collapse.
Coins made from pure metals historically showed zones of inhibition on bacterial culture plates.
Specific Applications of Heavy Metals
Silver nitrate: Used to prevent ophthalmia neonatorum (eye infections in newborns).
Mercuric chloride: Used as a preservative in paints to prevent fungal infections (mildew) in wooden structures despite toxicity.
Copper sulfate: Used as an algaecide in public water features to prevent toxic algal blooms (e.g., red tide).
Zinc chloride: Used in mouthwash as an oligodynamic metal to kill bacteria like thrush and Streptococcus mutans, which causes plaque.
Soaps and Detergents: Emulsification
Soaps and detergents contain lipids that attract other lipids.
They emulsify microorganisms, trapping them in bubbles which can be easily removed from the surface.
They do not detatch or disassemble the plasma membrane.
Emulsification: lipids and water do not interact, they repel each other to make a micelle (bubble)
Emulsification also is the process which lipids in an oil stick to the lipids in solid form (this is how we deal with eggs)
Quaternary Ammonium Compounds (Quats)
Quats are antimicrobial compounds that ionize proteins and disrupt plasma membranes, leading to collapse.
Effective against bacteria, fungi, amoebas, and enveloped viruses.
Ineffective against non-enveloped viruses and endospores and are generally expensive and not frequently used.
Chemical Food Preservatives
Chemical preservatives are infused to food in order to prevent bacteria and fungi growth, and keep food edible for a longer time
Most food spoilage is caused by microorganisms
Bananas produce ethylene gas -> overripens things and causes spoiling
Ethylene gas will ripen fruit
Sulfur Dioxide
It prevents bacterial growth and tining
Tining: wine spoils and becomes holy sour-vinegar/acetone
Wine rots due to weak structure of cork.
Organic Acids
In cereal or grains (even things like marshmallow like products)
Infusing acids changes the pH of the rains just slightly enough to stop the growth of mold and allow cereals to last longer
Nitrates and Nitrites
They cause stop the germination of endospores with high volumes of it in bacon and jerky meat.
Antibiotics
Naturally occurring chemical compounds that kill bacteria
Comes in types of either bacteriostatic (halt cellular processes, and stop metabolizing and growing), and the other one is bactericidal (causes irreparable cell damage, killing the cells).
Antibiotics = bactericidal, and therefore should not be perscribed for anything but bacteria.
Bacteriocins = a class of natrual antibiotics that are secreted by bacteria to prevent other bacteria from taking up space (cheese)
2 classes: niacins and natmycins, which kill gram positive bacteria on other cheeses and it don't need to be in the fridge with natural antimicrobial properties to it.
Aldehydes
There are a fringe group of double bonded oxygens in the center molecule, in which they cross link functional groups.
Functional groups all attached to each other in this way cause for functional collapse of cells, and ultimately cell death.
Good to use to preserve medical tools in autoclave and storage, but need a quick run of the autoclave when ready to use.
Preservation of Specimans
Formaldehyde is needed to preserve specimens
Glutaraldehyde is needed to supsend medical tool use
Barbicides = a low grade aldehyde suspended to kill bacteria, fungus, lice from you and the pay person. (barber salon)
Plasma
The 4th state of matter is the hyper acceleration of gas that disintegrates things down to molecular level, used to sterilize things.
Example of in Movie: avengers snapping fingers turn to dust
Important details to consider
Almost all chemicals cause protein change, but not all of them cause lipid damage, which you need to focus on, ask for which ones cause protein be denatured because that is likely the answer.