Supramolecular assembled nanogel made of mannan

Abstract

The supramolecular assembly of amphiphilic mannan, synthesized by the Michael addition of hydropho- bic 1-hexadecanethiol to vinyl methacrylated mannan, originates in aqueous medium the formation of a nanogel, stabilized by hydrophobic interactions among alkyl chains. The critical aggregation concentra- tion, calculated by fluorescence spectroscopy ranged between 0.002 and 0.01 mg/mL, depending on the polymer degree of substitution. The cryo-field emission scanning electron microscopy showed spherical macromolecular micelles with diameters between 100 and 500 nm. The dynamic light scatter- ing analysis revealed a polydisperse colloidal system, with mean hydrodynamic diameter between 50 and 140 nm, depending on the polymer degree of substitution. The nanogel is negatively charged, stable over a 6 months storage period, and stable at pH 3–8, salt or urea solutions. Bovine serum albumin and curcumin were spontaneously incorporated in the nanogel, being stabilized by the hydrophobic domains, opening the possibility for future applications as potential delivery systems for therapeutic molecules. In vitro assays were carried out to characterize the biocompatibility of the nanogel. A toxic effect of mannan-C16 was observed, specific to mouse macrophage-like cell line J774, not affecting mouse embryo fibroblast cell line 3T3 viability.