Sample preparation - cell disruption Cell disruption technology refers to a technique that uses external force to destroy cell membranes and cell walls, and release the contents of cells, including components of the target product. Since bacteria, yeast, fungi, and plants all have cell walls, but the composition is different, and the network of similar cells forms a network structure. Different, so the cell wall is different in firmness and the overall appearance is increasing. Although animal cells do not have a cell wall, they have a cell membrane, and a certain cell disruption method is required to break the membrane to achieve the purpose of extracting the product. The methods of cell disruption are mainly divided into chemical and mechanical methods. details as follows: Chemical method Osmotic impact crushing • Method: Osmotic shock is a milder method of disruption, using changes in osmotic pressure to cause rapid expansion and rupture of cells. Repeated freezing and thawing • Method: The cells are frozen at a low temperature (about -15 ° C), then thawed at room temperature, and repeated to break the wall. Enzymatic dissolution • Method: Using various hydrolases, such as lysozyme, cellulase, lipase, etc., the cell wall is decomposed to release the cell contents. Chemical reagent method • Method: Certain organic solvents (such as benzene, toluene), antibiotics, surfactants, metal chelators, denaturants and other chemicals can change the permeability of the cell wall or membrane to selectively infiltrate the contents. SDS (sodium dodecyl sulfonate) is a typical anionic surfactant method technology principle effect cost application Chemical method Osmotic impact Osmotic destruction of cells mild Cheap Animal tissue homogenate or cell suspension Enzymatic digestion The cell wall is digested and the cells are broken mild expensive Bacteria or yeast Solubilization method Surfactant dissolves cell wall mild Moderate Animal or plant tissue homogenate, DNA extraction Lipolysis method Organic solvent dissolves cell walls and destabilizes them Moderate Cheap Animal or plant tissue homogenate, DNA extraction Alkali treatment Saponification of alkali causes cell wall to melt severe Cheap Plasmid DNA extraction, RNA extraction Mechanical method Tissue masher • Method: The material is made into a thin paste liquid, placed in the cylinder about 1/3 of the volume, the lid is tightly closed, the governor is first dialed to the slowest position, and after the switch is turned on, the speed is gradually accelerated to the required speed. • Features: Generally used in animal tissues, plant fleshy seeds, tender leaf buds, etc., the speed can be as high as 10,000 rpm / M or more. Due to the large mechanical shear of the rotating blade, the preparation of some larger molecules such as nucleic acids is rarely used. Homogenizer • Method: First place the shredded tissue in the tube, then put it into the mortar and grind it back and forth, and move it up and down to grind the cells. The gap between the grinding wheel of the homogenizer and the inner wall of the glass tube is maintained at a distance of a few tenths of a millimeter. • Features: This method of cell breakage is higher than the high-speed tissue masher, suitable for small amounts and animal organs. • Problems: lumps or filamentous fungi that are more likely to cause blockage, smaller Gram-positive bacteria and some sub-organelles, which are hard and easy to damage the homogenate valve, are not suitable for treatment by this method. Grinding • Principle: The liquid nitrogen pre-freezing sample is placed in a mortar for grinding • Features: It is mostly used for hard plant materials. It is often added with a small amount of quartz sand, glass powder or other abrasives to improve the grinding effect. Ultrasonic • Principle: The cell suspension is treated with ultrasonic waves of a certain power to cause the cells to violently oscillate and rupture. The effects of ultrasound on the cells mainly have thermal effects, cavitation effects and mechanical effects. • Features: handling a small number of samples, simple operation, good repeatability, saving time; mostly used for microbial and tissue cell disruption, such as the preparation of various enzymes with E. coli. • There is a problem: the chemical radicals generated by ultrasonic waves can deactivate certain sensitive active substances; the sound energy transmission of large-capacity devices is difficult to dissipate heat, and corresponding cooling measures should be taken; sensitive to ultrasonic waves and nucleic acids should be used with caution. High pressure homogenization • Method: The sample is instantaneously released through the slit by using ultra-high pressure energy, and the cells are broken under the action of shearing effect, cavitation effect and collision effect. The whole process is carried out in a 4~6 °C low temperature circulating water bath to maintain the original material activity. • Features: It can be operated continuously and is suitable for processing a large number of samples. It is mainly used to extract intracellular products such as proteins from microbial samples. Oscillating bead breaking • Method: Place an equal volume of small tissue samples and high-density magnetic beads or steel balls into a sealable 2ml screw cap microtube, and set the oscillation speed and oscillation time. • Features: This method is currently the fastest and the most processed method at a time. A machine can process up to 2,400 samples in a day. Suitable for small, diverse experiments. method technology principle effect cost application Mechanical method Homogenization Cells are mashed by a blender Moderate Moderate Animal organization Grinding method The cells are ground by the grind Moderate Cheap Plant tissue Ultrasonic method Breaking the cells with the action of holes in the ultrasound Moderate expensive Cell suspension High pressure homogenization a small hole that must pass through the cell, causing the cell to be broken by shear severe Moderate Bacterial extract protein, yeast Bead mill crushing Cells are chopped by glass beads or iron beads severe Cheap Tissue homogenate Disposable Piercing Guide - WPTC12
Disposable surgical instruments are single-use medical devices that are used during surgery and discarded after use. Some examples of disposable surgical instruments include:
1. Scalpel 2. Tweezers 3. Scissors 4. Needle 5. Suture material 6. Surgical drapes 7. Surgical masks 8. Surgical gloves 9. Ironing pen 10. Trocar and cannula.
10. Laparoscopic instruments: Used for minimally invasive surgeries, these instruments include a camera and specialized tools for performing surgery through small incisions.
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2. Forceps: A tool used for grasping and holding tissues or organs during surgery.
3. Retractors: Surgical instruments used to hold open incisions or wounds to provide better visibility for the surgeon.
4. Scissors: Used for cutting tissues and sutures during surgery.
5. Hemostats: Used to clamp blood vessels and prevent bleeding during surgery.
6. Suction devices: Used to remove fluids or debris from the surgical site.
7. Needles: Used to suture or stitch wounds.
8. Electrocautery: A tool that uses an electrical current to cut or coagulate tissues during surgery.
9. Endoscopes: Used for minimally invasive surgeries, these instruments allow the surgeon to see inside the body without making large incisions.