|
Plaga
PLGA, PLG, or poly(lactic-''co''-glycolic) acid ( CAS: ) is a copolymer which is used in a host of Food and Drug Administration (FDA) approved therapeutic devices, owing to its biodegradability and biocompatibility. PLGA is synthesized by means of ring-opening co-polymerization of two different monomers: glycolide and lactide, the cyclic dimers (1,4-dioxane-2,5-diones) of glycolic acid and lactic acid, respectively. Polymers can be synthesized as either random or block copolymers thereby imparting additional polymer properties. Common catalysts used in the preparation of this polymer include tin(II) 2-ethylhexanoate, tin(II) alkoxides, or aluminum isopropoxide. During polymerization, successive monomeric units of glycolic or lactic acid are linked together in PLGA by ester linkages, thus yielding a linear, polyester as a product. Copolymer Depending on the ratio of lactide to glycolide used for the polymerization, different forms of PLGA can be obtained: these are usually identif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PLGA
PLGA, PLG, or poly(lactic-''co''-glycolic) acid (CAS Registry Number, CAS: ) is a copolymer which is used in a host of Food and Drug Administration (FDA) approved therapeutic devices, owing to its biodegradation, biodegradability and biocompatibility. PLGA is synthesized by means of ring-opening co-polymerization of two different monomers: glycolide and lactide, the cyclic dimers (1,4-dioxane-2,5-diones) of glycolic acid and lactic acid, respectively. Polymers can be synthesized as either random or block copolymers thereby imparting additional polymer properties. Common catalysts used in the preparation of this polymer include tin(II) 2-ethylhexanoate, tin(II) alkoxides, or aluminum isopropoxide. During polymerization, successive monomeric units of glycolic or lactic acid are linked together in PLGA by ester linkages, thus yielding a linear, polyester as a product. Copolymer Depending on the ratio of lactide to glycolide used for the polymerization, different forms of PLGA can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystallinity
Crystallinity refers to the degree of structural order in a solid. In a crystal, the atoms or molecules are arranged in a regular, periodic manner. The degree of crystallinity has a large influence on hardness, density, transparency and diffusion. In an ideal gas, the relative positions of the atoms or molecules are completely random. Amorphous materials, such as liquids and glasses, represent an intermediate case, having order over short distances (a few atomic or molecular spacings) but not over longer distances. Many materials, such as glass-ceramics and some polymers, can be prepared in such a way as to produce a mixture of crystalline and amorphous regions. In such cases, crystallinity is usually specified as a percentage of the volume of the material that is crystalline. Even within materials that are completely crystalline, however, the degree of structural perfection can vary. For instance, most metallic alloys are crystalline, but they usually comprise many independent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanoparticles
A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At the lowest range, metal particles smaller than 1 nm are usually called atom clusters instead. Nanoparticles are distinguished from microparticles (1-1000 μm), "fine particles" (sized between 100 and 2500 nm), and "coarse particles" (ranging from 2500 to 10,000 nm), because their smaller size drives very different physical or chemical properties, like colloidal properties and ultrafast optical effects or electric properties. Being more subject to the Brownian motion, they usually do not sediment, like colloid, colloidal particles that conversely are usually understood to range from 1 to 1000 nm. Being much smaller than the wavelengths of visible light (400-700 nm), nanoparticles cannot be seen with ordinary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prosthetic Devices
In medicine, a prosthesis (: prostheses; from ), or a prosthetic implant, is an artificial device that replaces a missing body part, which may be lost through physical trauma, disease, or a condition present at birth (congenital disorder). Prostheses may restore the normal functions of the missing body part, or may perform a cosmetic function. A person who has undergone an amputation is sometimes referred to as an amputee, however, this term may be offensive. Rehabilitation for someone with an amputation is primarily coordinated by a physiatrist as part of an inter-disciplinary team consisting of physiatrists, prosthetists, nurses, physical therapists, and occupational therapists. Prostheses can be created by hand or with computer-aided design (CAD), a software interface that helps creators design and analyze the creation with computer-generated 2-D and 3-D graphics as well as analysis and optimization tools. Types A person's prosthetic device should be designed and assembled t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Implant (medicine)
An implant is a medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. For example, an implant may be a rod, used to strengthen weak bones. Medical implants are human-made devices, in contrast to a transplant, which is a transplanted biomedical tissue. The surface of implants that contact the body might be made of a biomedical material such as titanium, silicone, or apatite depending on what is the most functional. In 2018, for example, American Elements developed a nickel alloy powder for 3D printing robust, long-lasting, and biocompatible medical implants. In some cases implants contain electronics, e.g. artificial pacemaker and cochlear implants. Some implants are bioactive, such as subcutaneous drug delivery devices in the form of implantable pills or drug-eluting stents. Applications Implants can roughly be categorized into groups by application: Sensory and neu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surgical Suture
A surgical suture, also known as a stitch or stitches, is a medical device used to hold Tissue (biology), body tissues together and approximate wound edges after an injury or surgery. Application generally involves using a Sewing needle, needle with an attached length of thread (yarn), thread. There are numerous types of suture which differ by needle shape and size as well as thread material and characteristics. Selection of surgical suture should be determined by the characteristics and location of the wound or the specific body tissues being approximated. In selecting the needle, thread, and suturing technique to use for a specific patient, a medical care provider must consider the tensile strength of the specific suture thread needed to efficiently hold the tissues together depending on the mechanical and shear forces acting on the wound as well as the thickness of the tissue being approximated. One must also consider the elasticity of the thread and ability to adapt to differe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grafts
Grafting refers to a surgical procedure to move tissue from one site to another on the body, or from another creature, without bringing its own blood supply with it. Instead, a new blood supply grows in after it is placed. A similar technique where tissue is transferred with the blood supply intact is called a flap. In some instances, a graft can be an artificially manufactured device. Examples of this are a tube to carry blood flow across a defect or from an artery to a vein for use in hemodialysis. Classification Autografts and isografts are usually not considered as foreign and, therefore, do not elicit rejection. Allografts and xenografts may be recognized as foreign by the recipient and rejected. * Autograft: graft taken from one part of the body of an individual and transplanted onto another site in the same individual, e.g., skin graft. * Isograft: graft taken from one individual and placed on another individual of the same genetic constitution, e.g., grafts betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medical Device
A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assurance before regulating governments allow marketing of the device in their country. As a general rule, as the associated risk of the device increases the amount of testing required to establish safety and efficacy also increases. Further, as associated risk increases the potential benefit to the patient must also increase. Discovery of what would be considered a medical device by modern standards dates as far back as in Baluchistan where Neolithic dentists used flint-tipped drills and bowstrings. Study of Archaeology, archeology and Roman medical literature also indicate that many types of medical devices were in widespread use during the time of ancient Rome. In the United States it was not until the Federal Food, Drug, and Cosmetic Act ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboxylic Acid
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl group (e.g., alkyl, alkenyl, aryl), or hydrogen, or other groups. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion. Examples and nomenclature Carboxylic acids are commonly identified by their trivial names. They often have the suffix ''-ic acid''. IUPAC-recommended names also exist; in this system, carboxylic acids have an ''-oic acid'' suffix. For example, butyric acid () is butanoic acid by IUPAC guidelines. For nomenclature of complex molecules containing a carboxylic acid, the carboxyl can be considered position one of the parent chain even if there are other substituents, such as 3-chloropropanoic acid. Alternately, it can be named ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water (molecule)
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food energy or organic micronutrients. Its chemical formula, , indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. In liquid form, is also called "water" at standard temperature and pressure. Because Earth's environment is relatively close to water's triple point, water exists on Earth as a solid, a liquid, and a gas. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis is the cleavage of Biomolecule, biomolecules where a water molecule is consumed to effect the separation of a larger molecule into component parts. When a carbohydrate is broken into its component sugar molecules by hydrolysis (e.g., sucrose being broken down into glucose and fructose), this is recognized as saccharification. Hydrolysis reactions can be the reverse of a condensation reaction in which two molecules join into a larger one and eject a water molecule. Thus hydrolysis adds water to break down, whereas condensation builds up by removing water. Types Usually hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both the su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexafluoro-2-propanol
Hexafluoroisopropanol, commonly abbreviated HFIP, is the organic compound with the formula (CF3)2CHOH. This fluoroalcohol finds use as solvent in organic chemistry. Hexafluoro-2-propanol is transparent to UV light with high density, low viscosity and low refractive index. It is a colorless, volatile liquid with a pungent odor. Production Hexafluoro-propan-2-ol is prepared from hexafluoropropylene through hexafluoroacetone, which is then hydrogenated.Günter Siegemund, Werner Schwertfeger, Andrew Feiring, Bruce Smart, Fred Behr, Herward Vogel, Blaine McKusick “Fluorine Compounds, Organic” in ''Ullmann's Encyclopedia of Industrial Chemistry'', John Wiley & Sons, 2007. :(CF3)2CO + H2 → (CF3)2CHOH Solvent properties As a solvent, hexafluoro-2-propanol is polar and exhibits strong hydrogen bonding properties. Testament to the strength of its hydrogen-bonding tendency is the fact that its 1:1 complex with THF distills near 100 °C. It has a relatively high dielectric co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
