Chemical penetration enhancers surfactants

Niosomes In order to circumvent some of the limitations encountered with liposomes, such as their chemical instability, the cost and purity of the natural phospholipids, and oxidative degradation of the phospholipids, niosomes have been developed. Niosomes are nonionic surfactant vesicles which exhibit the same bilay-ered structures as liposomes. Their advantages over liposomes include improved chemical stability and low production costs. Moreover, niosomes are biocompatible, biodegradable, and nonimmunogenic [215], They were also shown to increase the ocular bioavailability of hydrophilic drugs significantly more than liposomes. This is due to the fact that the surfactants in the niosomes act as penetrations enhancers and remove the mucous layer from the ocular surface [209]. 

The presence of fonnulation surfactants and solvents, which will facilitate skin penetration of the pesticide. Absorption rate is more effective for lipophilic materials. Some U V-absorbing chemicals can act as skin penetration enhancers, which may increase the pcrcutancou.s aKsoiption of pesticides and other formulation chemicals (Morgan... 

Surfactants and solvents are added to commercial pesticides to increase adsorption by targeted species. These chemicals also enhance the adsorption through mammalian skin. In a laboratory animal experiment, dermal penetration of atrazine, alachlor, and trifluralin was significantly lower for the pesticides alone than when contained in commercial versions of aU three. It was also shown that the solvents contained in the commercial trifluralin enhanced the dermal penetration of the other two commercial formulas when the pesticides were mixed together [30]. Pesticides are often applied in mixtures. This study shows that such mixing can have important implications for the health of those who come in contact with such mixtures. 

Uses Surfactant to enhance activity of agricultural chemicals penetrant to provide uniform coverage by decreasing surface tension of sol ns addifier to lower the pH of spraying sol n to prevent alkaline hydrolysis PastellM-08 [Lion]... 

No physical removal of cuticle has been observed with microscopic and chemical studies when the cuticle is treated with a surfactant, although solubilization of waxes has been suggested. It is likely that orientation of surfactant molecules occurs towards the cuticle surface causing wetting and spreading of the spray droplets over the leaf surface. This would enhance the penetration of the herbicide solution into stomata, insect punctures, cracks, and other imperfections in the leaf surface. 

For NR nanocomposite filled with silica, it has always been known that the hydrophilicity-hydrophobicity issue is a challenge since silica is hydrophilic and NR is hydrophobic. The usual method to overcome this issue is by adding coupling agent. In 1987 Wu and coworkers introduced admicellar polymerization where a thin polymeric film will be formed on the silica s surface. This process yields a thin film of polymer on the silica which can further enhance the adhesion between the surfaces of silica and rubber. The steps involved in admicellar polymerization are outlined in Scheme 7.7. In principle, a bilayer of surfactant, i.e. the admicelle, is first formed on the surface of the silica. Monomer will then penetrate the admicelle, i.e. the adsolubilization of monomer. Upon addition of initiator to the reaction system, in situ polymerization occurs in the admicelles. Finally, the surfactant is removed by washing with water and an ultrathin polymer layer is formed on the surface of the silica. The polymerization of the monomer in the admicelles can be induced by thermal process, chemical initiators or radiation. ... 

The term wash-in (W-1) effect was first used by Moody and Maibach [154] in describing the effect of solvents on enhancing the penetration of chemical contaminants rather than washing them off the skin [154]. This phenomenon was illustrated by an in vitro study [165]. In this experiment, decontamination with surfactants and saline enhanced the dermal penetration of... 

The activator surfactant is initially deposited together with the agrochemical and it can penetrate the cuticle, reaching other sites of action and, hence, the role of surfactant in the activation process can be very complex. The net effect of surfactant interactions at any of the sites of action is to enhance the mass transfer of an agrochemical from a solid or liquid phase on the outside of the cuticle to the aqueous phase of the internal tissues of the treated leaf. As discussed above, solubilisation can play a major role in activating the transport of the agrochemical molecules. With many non-polar systemic fungicides, which are mostly applied as suspension concentrates, the presence of micelles can enhance the rate of dissolution of the chemical and this results in increased availability of the molecules. It also leads to an increase in the flux as discussed above. 

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