Cleansing Mechanisms and Efficacy on Artificial Skin

Area of Science:

• Surface chemistry
• Personal care product formulation
• Dermatology

Background:

• Surfactants are key ingredients in personal care products for cleansing.
• Understanding cleansing mechanisms is crucial for developing effective formulations.
• Artificial skin models provide a reliable platform for studying surfactant performance.

Purpose of the Study:

• To systematically investigate the cleansing mechanisms of common surfactants on artificial skin.
• To characterize the removal of different soil types (sebum and dimethicone) using various surfactants.
• To evaluate the performance of surfactant mixtures and simple cleansing formulations.

Main Methods:

• Systematic study of artificial skin cleansing using disodium laureth sulfosuccinate (DSLSS), sodium laureth sulfate (SLES), sodium dodecyl sulfate (SDS), dodecyl trimethyl ammonium bromide (DTAB), and coco glucoside (CG).
• Characterization of soil removal mechanisms, focusing on emulsification and roll-up.
• Measurement of interfacial tension and surfactant adsorption on the artificial skin surface.
• In vitro evaluation of surfactant mixtures and simple cleansing formulations.

Main Results:

• Two primary cleansing mechanisms identified: emulsification (e.g., sebum with SLES) and roll-up (e.g., dimethicone with DTAB).
• Roll-up effectiveness is linked to surfactant interfacial activity and adsorption; strong adsorption of DTAB enabled roll-up at higher interfacial tension.
• Anionic and nonionic surfactants required lower interfacial tension (<5 mN/m) for roll-up.
• Nonionic coco glucoside (CG) was effective at lower concentrations for dimethicone removal.
• Combinations of CG with ionic surfactants enhanced cleansing at reduced total concentrations.

Conclusions:

• Cleansing efficacy is governed by specific mechanisms (emulsification vs. roll-up) dependent on surfactant type and soil composition.
• Surfactant adsorption and interfacial activity are critical factors influencing the roll-up mechanism.
• Optimized surfactant mixtures, particularly those including CG, can improve cleansing performance and allow for lower overall surfactant concentrations in formulations.