Evaluation Methods for Conditioned Hair
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
Jachowicz et al. (78) use charge decay measurements from charges generated in their apparatus as a means of getting information on the mechanism of fiber conductivity. They conclude from their studies that the effective work functions and charge decay are strongly affected by fiber surface modification and are the controlling factors in the effectiveness of an antistatic agent. Modification of the hair fiber surface by adsorption of cationic polymers and the formation of polymer-detergent complexes changes both its effective work function and its conductivity, but in practice, static charge generation cannot be controlled by these compounds. However, Jachowicz et al. concede that during combing, parameters such as fiber elongation, stress, and magnitude of frictional forces result in nonuniform distribution of triboelectric charge densities along the length of the hair tress, which might lead to quantitatively different results than those presented in their paper (78). Luster or Shine of Hair
Cationic Surfactants and Quaternary Derivatives for Hair and Skin Care
Randy Schueller, Perry Romanowski in Conditioning Agents for Hair and Skin, 2020
Medley (51) postulated that an antistatic agent need not be present as a continuous film in order to be effective. A discontinuous film would not give long-range conductivity and, therefore, the half-life of charge mobility would remain high. Medley proposed a mechanism requiring only localized conductivity at the contact site. This mechanism could be acting as a secondary effect. Another secondary effect could be a change in the chemical nature of the fiber surface, which would alter the magnitude of charge generated. Lunn and Evans (37) believed that the reduction of combing force by lubrication is the primary mechanism involved. We now know that quaternary ammonium antistatic agents do not normally achieve their effect by mechanisms of increased conductivity or of charge dissipation. Their primary effect is a lubricating action, which reduces substantially the force required to comb hair, especially the end peak force. The reduced normal contact force between hair fibers and comb leads to a reduction of static charge generated on the hair. The adsorption on hair of long-chain alkyl quaternary ammonium salts, cationic polymers, and complexes of cationic polymers with anionic polymers or anionic detergents can produce significant changes in the electrochemical surface potential of the fiber. This results in different charging characteristics in relation to polymers and metals. The effect of treatments such ad dyeing, bleaching, and permanent waving was also explored. Apart from altering the electrochemical potential, surface modification may also affect the conductivity of fibers (37,52). Modification of hair surface by reduction, bleaching, and oxidative dyeing results in very small changes of charging characteristics as compared to untreated fibers. They also have an insignificant effect on the fiber conductivities at low humidity.
Fabrication, optimisation and evaluation of cisplatin-loaded nanostructured carriers for improved urothelium permeability for intravesical administration
Published in Journal of Microencapsulation, 2021
Ting-Yu Chen, Yu-Yao Tai, Li-Ching Chang, Pao-Chu Wu
In this study, capryol 90, cetrimonium bromide, and mixture of 1,5-pentanediol and transcutol were used as oil phase, surfactant, and cosurfactant, respectively, to prepare the cisplatin-loaded microemulsion. Capryol 90 is an oil which has been investigated extensively for the preparation and optimisation of microemulsions of various poorly soluble drugs both in vitro as well as in vivo (Shakeel et al. 2013). Cetrimonium bromide is a quaternary ammonium salt, and has frequently been used for a variety of purposes such as antistatic agent, cleansing agent, emulsifying agent, and suspending agent in cosmetic products at concentrations of up to 10% (w/v) (Becker et al. 2012). Cosurfactant can reduce the amount of surfactant needed to formulate microemulsion, due to it softening up the interface surfactant film between oil/water phases and increases equilibration rate and formation of low-viscosity microemulsions; however, while alcohol is used as cosurfactant to decrease solubility of oil and water in microemulsions, the value of interfacial tension would increase with certain surfactants. This disadvantage might be countered by using mixtures of cosurfactant (Negin et al. 2017). 1,5-Pentanediol and transcutol are common cosurfactants and they also possess penetration enhancement effect (Alany et al. 2000, Osborne et al.2018), thus, the mixture of 1,5-pentanediol and transcutol was used as cosurfactant. Methylcellulose is a hydrophilic cellulose and is used to increase the viscosity of microemulsions. From our preliminary study, the amount of surfactant needs to be larger than 2% (w/w), and the microemulsion formulation is easy to form, so the amount of cetrimonium bromide was fixed at 2% (w/w). In this study, the effect of additional amount of oil phase and cosurfactant on permeability was investigated. A total of 12 model formulations were prepared as per the factorial experimental design, except for formulation 11 with a high-amount oil phase and a low-amount cosurfactant presence so cannot form formulation. The size of the vesicles was found to vary between 235.8 and 309.3 nm, which were in nanoscale. The PDI of model formulations ranged from 0.15 to 0.21, indicating the mono-dispersed microemulsions were obtained (Liu et al. 2011). The viscosity of formulations ranged from 550.8 to 861.7 cps. The zeta potential ranged from 52.70 to 88.8. It was found that the zeta potential increased with the increase of X1. In general, successful passive transdermal delivery is restricted to particle size being less than 500 nm (Kohli et al.2004), indicated that the designed carrier had potential to improve the permeation capability of drug. The image of the cisplatin-loaded microemulsion is shown in Figure 1.
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