Polyethylene glycol , stabilizing agent

The stabilizing of aqueous latexes succeeded by using emulsifiers (anionic, nonionic) and/or their mixture, steric stabilizators (polyvinyl alcohol (PVOH), hydroxyethyl cellulose, polyethylene glycol, new protective colloids etc.), and polymerizable surfaces active agents, in general. Vinyl acetate (VAc) emulsion homopolymers and copolymers (latexes) are widely used as binders in water-based interior and exterior architectural paints, coatings, and adhesives, since they have higher mechanical and water resistance properties than the homopolymers of both monomers [2, 4, 7]. 

Efforts should be made to stabilize an enzyme s activity. Certain agents (such as glycerol, ammonium ions, boric acid, polyethylene glycol, and even talcum powder or bentonite clay) have proven widely to be effective enzyme stabilizers. For multisubstrate enzymes, inclusion of one particular substrate with the enzyme (in the absence of other substrates or cofactors) often stabilizes an enzyme s catalytic activity. Such a substrate may also assist in unlocking the enzyme from a particularly inactive conformational form. In addition to substrates, other ligands and effectors (including reaction products. 

Polyethylene glycol has been used as reducing and stabilizing agent for Au NPs. The stability of the resulting Au colloids and the reaction rates are dependent on polymer molar mass. The Au NPs are characterized using UV-Vis, analyzing the plasmon bands [108]. 

One of the critical factors in excipient selection and concentration is the effect on preferential hydration of the biopharmaceutical product [53, 54], Preferential hydration refers to the hydration layers on the outer surface of the protein and can be utilized to thermodynamically explain both stability enhancement and denatur-ation. Typical excipients used in protein formulations include albumin, amino acids, carbohydrates, chelating and reducing agents, cyclodextrins, polyhydric alcohols, polyethylene glycol, salts, and surfactants. Several of these excipients increase the preferential hydration of the protein and thus enhance its stability. Cosolvents need to be added in a concentration that will ensure their exclusion from the protein surface and enhance stability [54], A more comprehensive review of excipients utilized for biopharmaceutical drug products is available elsewhere [48],... 

Cryo- and Lyoprotectants and Bulking Agents Various mechanisms are proposed to explain why excipients serve as cryo- or lyoprotectants. The most widely accepted mechanism to explain the action of cryoprotection is the preferential exclusion mechanism [177]. Excipients that will stabilize proteins against the effects of freezing do so by not associating with the surface of the protein. Such excipients actually increase the surface tension of water and induce preferential hydration of the protein. Examples of solutes that serve as cryoprotectants by this mechanism include amino acids, polyols, sugars, and polyethylene glycol. 

Aqueous polyethylene glycol solutions can be used either as suspending agents or to adjust the viscosity and consistency of other suspending vehicles. When used in conjunction with other emulsifiers, polyethylene glycols can act as emulsion stabilizers. 

Thoma K, Ullmann E, Zelfel G. Investigation of the stability of penicillin G sodium in the presence of nonionic surface active agents (polyethylene glycol derivatives) [in German]. Arch Pharm 1962 295 670-678. 

The above agents are delivered in a variety of forms. Their compatibility with various solvents (propellants, alcohol, water), liquids (glycerol, polyethylene glycol, oleic acid, sorbitan trioleate, lecithin), and solid (lactose) phase excipients is key to the chemical and physical stability of the products. The Handbook of Pharmaceutical Excipients lists most of these materials.35... 

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