Imaging the Detergency of Single Cotton Fibers with Confocal Microscopy: the Effect of Surfactants and Lipases

Abstract

Detergency mechanisms of lipids from single cotton fibers were visualized by means of confocal laser scanning microscopy (CLSM). Fibers were soiled with different types of lipids: olive oil, lard and tri-C 10 , and subsequently stained with the fluorescent probe Nile Red. A surfactant composition of 300 lM C 12 E 6 /LAS (1:2 mol%) was used to mimic the surfactants used in a common washing solution. It was evident from the captured image series that the different kinds of soiling were removed by different mechanisms by the surfactants, depending on the fluidity of the lipid. Roll-up was the main mechanism when removing olive oil, whereas emulsification (necking) and/or solubilization were observed in the removal of lard and tri-C 10 . Only 20-25% of the olive oil remained after treatment with surfactants, which was much less compared to the solid fats where roughly 50% remained at end of treatment. The effect of adding lipases to the detergent formulation was clearly seen, both by an apparently higher rate of removal of olive oil but also using double injection when removing lard. A first injection of only surfactants removed a certain part of the lard as emulsion droplets stuck onto the fiber. A second injection of both lipases and surfactants was able to remove some of the preformed emulsion particles and reduce the overall remaining lard content on the cotton fiber.

Analysis of Cleaning Process for Several Kinds of Soil by Probability Density Functional Method

“…In order to analyze the mechanism of oily soil removal during washing, many studies have been conducted by applying various methods such as molecular dynamics simulations 22 , combined molecular dynamics and quantum mechanics 23 , lattice Monte Carlo simulations 24 , confocal laser scanning microscopy 25 , a scanning fluid dynamic gauging device 26 , and the quartz crystal microbalance technique 27 .…”

The Role of Decorated SDS Micelles in Sub-CMC Protein Denaturation and Association

“…1,2 Furthermore, proteinsurfactant interactions reveal new facets about the types of conformational changes that proteins may undergo in response to a changing environment. While both nonionic and ionic surfactants can increase the activity of lipases, 3,4 ionic surfactants generally denature proteins at low concentrations through a combination of ionic and hydrophobic interactions. 5,6 The classical model of protein denaturation by sodium dodecyl sulfate (SDS) is based on the pioneering work of Tanford 7 and has been confirmed by more recent reports.…”

Development of an Environmentally Acceptable Detergent Formulation for Fatty Soils Based on the Lipase from the Indigenous Extremophile Pseudomonas aeruginosa Strain

“…The predominant rolling-up mechanism causes a reduction of the interfacial tension, triggering a gradual increase of the fabric-soil contact angle, enabling further emulsification of detached soil in emulsion droplets aided by hydrodynamic forces in the agitated bath [27]. Also, on a molecular level, the soil is solubilized in the interior of the surfactant micelles [28]. These mechanisms can operate separately, simultaneously or consequently.…”