Speaking of disinfection, what do you think of? Is it the pungent smell of disinfectant from the hospital? Or is it the irritation brought by cold alcohol? Or is it the ultraviolet lamp with cyberpunk temperament? If it’s just these, you are wrong, or in other words, demonizing disinfection. What we can hardly imagine is that the concept of disinfection has almost run through human history, and even accompanies our lives all the time.
Clean, wipe and disinfect easily GET
Speaking of cleaning and disinfection, we may think of many things, such as alcohol wiping. However, the most effective and convenient way to disinfect is to wash your hands.
Once, doctors didn’t wash their hands! Until the late 19th century, the father of epidemiology, Symmelweis, discovered that doctors hand washing after giving birth to pregnant women can effectively reduce maternal mortality. Since then, hand washing has been passed down as a doctor’s basic operating norm. Nowadays, doctors have strict requirements for hand washing. Strictly abide by the seven-step hand washing method, which can kill most of the bacteria in the hands.
However, it is not that running water helps us wash away these bacteria, but that hand sanitizer and soap help us kill pathogens. The principle of hand sanitizer and soap sterilization is actually very simple. The first is to wash off the oil and dust on the surface through the action of surfactants, which usually contain a lot of bacteria. The second is because the main components of bacterial cell walls are peptidoglycan, teichoic acid and lipopolysaccharide, etc., which will denature and die when exposed to strong acids, alkalis or heavy metals. As an alkaline substance, soap can destroy the cell wall of bacteria and achieve the purpose of killing bacteria. Of course, some triclosan and o-phenylphenol are also added to the hand sanitizer and soap to help destroy the structure of the bacterial cell wall and achieve the purpose of sterilization.
In addition to soap and disinfectant, what other disinfectants can we see in our home life? By the way, it is alcohol and iodophor. When we are accidentally injured, we always have to apply some alcohol or iodophor to sterilize and prevent infection. Why can this ordinary alcohol kill bacteria and viruses? It is because alcohol can destroy the protein structure of microorganisms. Alcohol will absorb the water in the bacteria body, making it dehydrated and solidified. Someone may notice that the concentration of alcohol we use for disinfection is 75%, so is it that the stronger the alcohol, the better the disinfection effect? This is not the case. Stronger alcohol will not only not bring better disinfection effect, but will also reduce the sterilization power. Don’t forget that there is protein on the surface of bacteria. If the dehydration is too rapid, a hard protein shell will form on the surface of the bacteria, preventing the subsequent penetration of alcohol and reducing the efficiency of sterilization. Alcohol sounds effective and cheap, but it is not a panacea. Because alcohol cannot kill the spores produced by bacteria and some specific viruses. Spores are a kind of “seed” produced by bacteria that are more resistant to cold, heat, and resistance to unfavorable environments. At a suitable temperature, the spores will resuscitate and become active adult bacteria. Therefore, alcohol wipes can only be disinfected, not sterilized.
However, alcohol disinfection has a big disadvantage-applying alcohol is too painful! Is there a way to disinfect it that doesn’t hurt? Another commonly used disinfectant is iodophor. The active ingredient of iodophors is complexed iodine, which can bind to bacterial proteins, thereby causing denaturation of amino acids and enzymes to achieve the purpose of sterilization. Due to its low irritation and high sterilization efficiency, iodophor is now a “star” class disinfectant. But remember, if it is disinfected with iodine (also called tincture of iodine), remember to wipe it off with alcohol. Because the elemental iodine contained in iodine, staying on the skin surface for a long time will damage the skin.
High temperatures and low temperatures leave the virus nowhere to hide
The purpose of all disinfection is to kill potential pathogens, except for seemingly invasive chemicals, other conventional methods can also kill them. Pathogens are also organisms, so what are organisms afraid of? By the way, high temperature! High temperature sterilization can be described as the most affective sterilization method that accompanies mankind. Simply put, all the process of cooking food is a high temperature sterilization process. We are most familiar with boiling water. The habit of drinking hot water in the American Chinese workers in the 19th century reduced the incidence of many epidemics. So far, this method of sterilization has also been passed down.
There is no doubt that high temperature can be sterilized. But did you know that low temperature can still kill pathogens? It is said that in the 19th century, the French found that wine always turned sour, affecting the flavor, so they invited the microbiologist Pasteur to see what went wrong. Pasteur saw that it was Acetobacter in the wine. However, the wine cannot be heated at high temperature, because the boiled wine will lose its aroma. Therefore, Pasteur invented a low-temperature sterilization method: low-temperature processing of wine at 60 ℃ for half an hour, effectively killing Acetobacter. What is the principle? In fact, the conditions for the survival of microorganisms are relatively harsh. A treatment at 60°C for 30 minutes is sufficient to kill a large number of microorganisms. Of course, it does not work against some heat-resistant spores and thermophilic bacteria.
This treatment method is used in the treatment of milk. This disinfection method is used in the treatment of milk. Fresh milk is difficult to store because it contains a lot of microorganisms. Use 70℃ to heat it for tens of seconds, and then quickly cool it down to 4～5℃, so that the milk can be kept for a longer time. Such a treatment method is also called pasteurization. This milk flavor will be better preserved.
So, can low-temperature sterilization completely kill all pathogenic microorganisms? Of course it is possible. For some utensils that are not resistant to high temperatures, we will use some special low-temperature sterilization methods to treat them. In a special instrument, some chemical vapors are filled, usually epoxy acetic acid, low-temperature vapor formaldehyde, and peroxyacetic acid. Then, the purpose of killing pathogens is achieved by low temperature treatment. For some complicated packaging, not resistant to heat, humidity and high temperature, devices with complicated structures are usually handled in this way, such as medical endoscopes, gloves, cardiac pacemakers, etc. But these drug vapors are also harmful to the human body. Therefore, when sterilizing at low temperature, the air tightness of the instrument must be strictly ensured, and the instrument must be turned on after the steam is emptied. This is actually a variant of fumigation.
Ultraviolet disinfection lamp is healthier
Have you ever been urged by your mother to “disinfect the quilt”? You may be wondering, can basking in the quilt really achieve the effect of disinfection? That’s right, it’s really ok. Because there is something in the sun that makes people love and hate-ultraviolet rays.
Ultraviolet rays can make people’s skin aging and darken fair skin, but we should not neglect its sterilization effect. Under long-term ultraviolet radiation, the structure of bacterial DNA and RNA will be destroyed. We know that DNA and RNA are the genetic material of organisms. When the mutation reaches a certain amount, the bacteria will die.
How pasteurization works
The wavelength of ultraviolet light is very short, and we can hardly see it. Ultraviolet light with a wavelength of 250 to 260 nanometers can play a very good sterilization effect. Therefore, such sterilization methods are also widely used in the sterilization of various large-scale factories and fixed equipment. During homework. Sometimes we will see a blue lamp hung on the roof of the school cafeteria, which is an ultraviolet disinfection lamp. You must avoid it when you see it open! Do not look directly or expose to ultraviolet light, otherwise it will burn the skin, impair vision, and in severe cases, it will cause blindness and skin cancer. Didn’t you say that ultraviolet light is not visible light? Why can you see the blue light again? I’m not wrong. Although ultraviolet light is invisible to humans, the actually manufactured ultraviolet lamp can emit light with a wider spectrum. A small part of its wavelength belongs to the blue wavelength range, so blue light can be seen. .
Ultraviolet light can emit light with a wide spectrum, and a small part of its wavelength belongs to the blue wavelength range, so blue light can be seen
In addition to ultraviolet light, what else can achieve the effect of destroying the genetic material of bacteria for sterilization? Of course there is, that is radiation! Don’t be afraid of radiation when you hear it. Making good use of radiation can benefit mankind. For example, X-rays can not only produce spooky films, but also sterilize them. We will use a certain dose of ionizing rays with extremely short wavelengths to kill microorganisms on the surface of the object to achieve the purpose of disinfection. X-rays, gamma-rays and electron rays are commonly used. These rays are produced by some isotopes, such as cobalt 60 and cesium 157. The protective clothing, masks, gloves, etc. commonly used by medical staff are all sterilized by irradiation.
Does this method of sterilization sound unsafe? No, we have to figure out the difference between radiation and radiation source first. Radiation refers to the process by which high-energy rays pass, and the radiation source refers to an object that continuously emits radiation outward. It can be simply understood that the radiation source is a water gun, radiation is the process of spraying water, and the sprayed water is the emitted rays. Irradiation sterilization does not leave the radiation source on the article, but just spray it with a water gun for sterilization and sterilization. What’s so scary?
Nowadays, the most common place for irradiation sterilization is food sterilization. Yes, by controlling the radiation dose, we can achieve a disinfection effect that not only kills pathogens, but is harmless to the human body. In addition, beef, chicken, ham, pork, sausage, fish and shrimp, etc., which have been completely sterilized by irradiation, can be stored for more than 2 years at room temperature, and can maintain the color and flavor, but not the soft taste of can Than. Most foods in the food industry are now sterilized by irradiation. Pick up the snacks at hand and see if there is also “irradiation sterilization” on it?
Technology is developing rapidly. In addition to the above common disinfection methods, there are many other methods to kill pathogens. After understanding the structure of the pathogen, you can prescribe the right medicine and choose the appropriate disinfection method. As ordinary people, we certainly do not need to make our living environment as “clean” as a sterile room, but it is still necessary to maintain good hygiene habits.