Chemical Control Methods

Plasma Membrane Injury by Phenolic Compounds

Phenolic compounds injure plasma membranes, causing leakage, but don't rupture them.
They strip lipids, maintaining structural integrity while cells slowly lose fluid.
Excessive leakage leads to cell death due to loss of osmotic pressure and cytosol.
Analogy: Like poking holes in a water balloon; eventually, it will run out of water.

Phenols in Everyday Products

Phenols are common in plastics and antimicrobial products.
Many antimicrobial plastics contain phenolic compounds.
Humans encounter phenols daily, often unknowingly.
Phenols are mildly antimicrobial but not the most effective for chemical control.

Bisphenols: Enhanced Antimicrobial Action

Bisphenols are two phenols joined together (e.g., o-phenyl phenol).
Bisphenols are highly effective antimicrobials, causing:
- Plasma membrane injury and leakage.
- Permanent disruption of new phospholipid formation, preventing repair.
- Inhibition of cell reproduction by stopping cytokinesis during mitosis or binary fission.

Bisphenols in Food Packaging and Concerns

Bisphenols are used as additives in plastic food containers to keep food fresh by inhibiting bacteria.
Paper is cheaper but doesn't have antimicrobial properties.
Problem: Bisphenols leach out of plastics into liquids, especially with heat.

Microplastics and BPA-Free Products

Bisphenols become microplastics that leach into water, ending up in the brain, placenta, and testicles.
Companies promote BPA-free water bottles to avoid bisphenols.
Ethical discussion: Are bisphenols worth the risk due to their potential harm to humans?
Birth defects are being seen as a result of BPA, affecting plasma membrane formation and mitosis.

Forever Chemicals and Molecular Stability

Bisphenols are classified as "forever chemicals" because they are found in many places and persist in the body.
The body struggles to break down their unusual molecular shape, specifically the bond between hexone rings.

Essential Oils: Plant Immune Systems

Essential oils are plant immune systems, defending against infections.
They consist of naturally antimicrobial hydrocarbons and lipids.
Examples: Peppermint, pine, orange, lemon, and ginger oils.

Phenolic Composition of Essential Oils

Many essential oils contain phenolic compounds like carbacrol (oregano oil).
Essential oils are naturally occurring phenols and terpenes (phenols without oxygen).
Effective against soil bacteria, especially gram-positive bacteria.

Extraction of Essential Oils

Extraction involves cutting leaves/stems, boiling to reduce volume, and separating tissue from oils.
Often cheaper to buy in bulk.

Aromatic Nature of Phenols and Cleanliness

Essential oils (peppermint, pine, lemon, etc.) are aromatic.
These smells are associated with cleanliness because they indicate the absence of bacteria.
Natural coevolution: Our brains associate these smells with clean environments due to their antimicrobial properties.

Practical Considerations for Essential Oils

Don't rely on swap meet oils for direct skin application; benefits are mild.
Inhaled oils primarily open bronchi, not kill lung bacteria.

Efficacy Against Gram-Positive Bacteria

Essential oils target peptidoglycan synthesis, disproportionately harming gram-positive bacteria.
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.