This glossary is provided to help scientists, researchers and medical professionals interested in utilizing Lifecore’s hyaluronan products or developing new applications and products using sodium hyaluronate.
Bacterial fermentation – a process in which bacteria convert organic compounds (usually carbohydrates) to make products. Lifecore uses bacterial fermentation to make hyaluronan.
Dalton (Da.) – is a unit of mass. It designates 1/16th of the mass of oxygen -16, the lightest and most abundant isotope of oxygen. Since this is 15.9949, the Dalton is equivalent to 0.9997 mass unit.2
Depolymerization – reduction in length of a polymer chain to form shorter polymeric units. Depolymerization may reduce the polymer chain to smaller molecular weight polymers, oligomeric, or monomeric units, or combination thereof. In hyaluronan, acid hydrolysis of the glycosidic bonds is the primary mechanism2.
Degradation – change in the chemical structure, physical properties or appearance of a material. Degradation of polysaccharides occurs via cleavage of the glycosidic bonds, usually by acid catalyzed hydrolysis. Degradation can also occur thermally and by alkali. It is important to note that degradation is not synonymous with decomposition. Degradation is often used as a synonym for depolymerization when referring to polymers. Degradation (depolymerization) of hyaluronan may also occur enzymatically by the action of hyaluronidases2.
Elasticity – the ability of a material to recover its original shape partially or completely after the deforming force has been removed.
Hyaluronan – also known as hyaluronic acid or sodium hyaluronate, hyaluronan is a linear (unbranched) polysaccharide or non-sulfated glycosaminoglycan, composed of repeating disaccharide units of N-acetyl glucosamine and glucuronate (linked by β 1-3 and β 1-4 glycosidic bonds) and counter ions. It is distributed widely throughout connective, epithelial and neural tissues as part of the extra-cellular matrix. There are high concentrations in the vitreous and aqueous humor of the eye, synovial fluid, skin, and the umbilical cord (Wharton jelly). The average 70-kg man has roughly 15 grams of hyaluronan in his body, one-third of which is turned over (degraded and synthesized) every day. It is an evolutionarily conserved molecule being found in both the group A and C Streptococci and Pasteurella multocida as well as birds, mammals, and other orders of animals. In solutions of moderate to high molecular weight (500,000 to >3 million Da.) at low concentrations it imparts considerable viscosity to aqueous solutions.
Hyaluronic acid – The acid form of Hyaluronan.
Hyaluronidase – Hyaluronidase are a family of enzymes that degrade hyaluronan. The enzyme is found in most animal species and many micro-organisms. There are a number of different types of hyaluronidase with different specificity and kinetics.
Molecular mass average (molecular weight average) – the given molecular weight (Mw) of hyaluronan will always represent an average of all the molecules in the population.
Oligosaccharide – a carbohydrate containing from two up to ten simple sugars linked together (e.g., sucrose, composed of dextrose and fructose). Beyond ten they are called polysaccharides.1
Polysaccharide – a combination of nine or more monosaccharides, linked together by glycosidic bonds.4
Sodium hyaluronate (NaHy) – the sodium salt form of hyaluronan.
Sterile – the absence of living organisms or viruses.
Viscosity – The internal resistance to flow exhibited by a fluid; the ratio of shearing stress to rate of shear. A liquid has a viscosity of one poise if a force of one dyne per square centimeter causes two parallel liquid surfaces one square centimeter in area and one centimeter apart to move past one another at a velocity of one centimeter per second. One poise equals 100 centipoise (cp).
Water is the primary viscosity standard with an accepted viscosity at 20°C of 0.01002 poise. Hydrocarbon liquids such as hexane are less viscous. Molasses may have a viscosity of several hundred centistokes, while for a very heavy lubrication oil the viscosity may be 100 centistokes. There are many empirical methods for measuring viscosity which generally involve measurement of the time of flow or movement of a ball, ring or other object in specifically shaped or sized apparatus’s. Lifecore measures the viscosity of hyaluronan solutions using Brookfield cone and plate viscometers at 25°C, with a variety of rotational speeds depending upon the instrument and viscosity.
Dynamic (absolute) viscosity – is the tangential force per unit area required to move one horizontal plane with respect to the other at unit velocity when maintained a unit distance apart by the fluid. Dynamic viscosity is often expressed in the metric CGS (centimeter-gram-second) system as g/cm.s, or poise (p).3
Intrinsic viscosity – is the limiting value of the specific viscosity at infinite dilution (i.e. zero concentration) of a solution.
Kinematic viscosity – dividing Viscosity by the liquid density at the same temperature give kinematic viscosity in centistokes (cs). One hundred centistokes equal 1 stoke. To determine kinematic viscosity, the time is measured for an exact quantity of liquid to flow by gravity through a standard capillary.
Zero-shear viscosity – is the low shear rate limiting value of viscosity (i.e when a solution is at rest).
Viscosupplementation – is a name given to the medical procedure of injecting hyaluronan based solutions into the synovial joint space of patients with osteoarthritis.
1The Condensed Chemical Dictionary, 10th Edition, 1981. Revised by G.G. Hawley. Von Nostrand Reinhold Company.
2ASTM F2347 Standard Guide for Characterization and Testing of Hyaluronan as Starting Materials Intended for Use in Biomedical and Tissue Engineered Medical Product Applications.
4Balazs, E.A.; T.C. Laurent; R.W. Jeanloz, “Nomenclature of Hyaluronic Acid”, Biochemical Journal Letters, 1986, Vol. 235, pp 903.