Thermoresponsive hydrogels with low toxicity from mixtures of ethyl(hydroxyethyl) cellulose and arginine-based surfactants.

Ethyl(hydroxyethyl) cellulose (EHEC) is known to form hydrogels in water at elevated temperatures in the presence of an ionic surfactant. In this paper, the potential use of arginine-based surfactants is explored considering the production of a low toxicity thermoresponsive hydrogel for pharmaceutical and biomedical applications. The interactions between EHEC and the monomeric surfactant N(α)-lauroyl-L-arginine methyl ester (LAM) and two gemini surfactants N(α),N(ω)-bis(N(α)-acylarginine) α,ω-dialkyl amides were evaluated by Rheo-Small Angle Light Scattering measurements. The complex viscosity of the systems was dependent on surfactant concentration and temperature. Under specific conditions, soft gels of homogeneous structure were produced. The cloud point (CP) of the EHEC-LAM system varied significantly with surfactant concentration, while only moderate CP changes were found in the presence of the gemini surfactants. Finally, the effect of the surfactants on the viability of a human cell line was evaluated. Despite the lower toxicity of LAM, the superior gel forming efficiency of the gemini surfactants at lower concentrations revealed their advantageous suitability as components of a biocompatible thermoresponsive gel system.