Aggregation behavior of self-assembled nanoparticles made from carboxymethyl-hexanoyl chitosan and sodium dodecyl sulphate surfactant in water

• Published in: Journal of molecular liquids 2019-03, Vol.278, p.253-261
• Main Authors: Rengifo, Andrés F.C., Santos, Sandra C., de Lima, Vania R., Agudelo, Alvaro J.P., da Silva, Luis H.M., Parize, Alexandre L., Minatti, Edson
• Format: Article
• Language: English
• Subjects: Carboxymethyl-hexanoyl chitosan; Conductivity; Dynamic light-scattering (DLS); Isothermal titration calorimetry (ITC); Polymer surfactant complex; Surface tension
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2018.12.125

Biopolymers can be used to produce nano-objects in solution and they are generally of low cost and biocompatible. However, they commonly have low kinetic stability and form aggregates with a broad particle size distribution, characteristics that hinder their use in drug delivery systems. Herein, we report the thermodynamics and mechanisms underlying the formation of nanostructures through the self-assembly of carboxymethyl-hexanoyl chitosan (ONCHC) and the effect of the presence of the surfactant sodium dodecyl sulfate (SDS). The pre- and post-aggregation regimes were monitored using several techniques and indicated that self-assembly is thermodynamically favorable. The presence of SDS decreased the hydrodynamic radius and surface charge of the SDS-ONCHC nanoaggregates and increased the kinetic stability in aqueous solution over a period of 150 days. The SDS-ONCHC interaction is driven mainly by a hydrophobic effect and the addition of SDS increases the number and strength of the hydrophobic domains, where the integral enthalpy change for the aggregate formation is −2.11 kJ mol−1. [Display omitted] •Water-soluble ONCHC was successfully obtained and characterized by 1H NMR and FTIR spectroscopy.•The ONCHC aggregation was monitored by surface tension and DLS analysis.•Thermodynamic and aggregation characteristics of SDS-ONCHC were determined.•SDS and ONCHC formed a stable complex in water through hydrophobic interactions.•SDS promotes a narrowing of the size distribution of ONCHC nano-aggregates.