Porous Chitin Microbeads for More Sustainable Cosmetics

The microbead form is a material architecture that is promising for use in biomedical and cosmetic applications; however, the use of petroleum-based microbeads (i.e., plastics) has raised significant environmental concerns in recent years. Microbeads prepared from renewable polymers could represent a sustainable alternative to these synthetic microbeads. This work explores the use of chitin in preparing biodegradable, biocompatible microbeads of low toxicity. Chitin microbeads were synthesized using the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C(2)mim][OAc]); the IL was used to both extract chitin directly from waste shrimp shell and to prepare the porous microbeads by coagulation in polypropylene glycol (PPG). The effects of biopolymer source and bead-preparation parameters on the formation of beads were investigated, as well as the effects of the drying conditions on the dry bead structure. It was found that IL-extracted chitin could be used to prepare beads of homogeneous size distribution (with 60% of beads 125-250 mu m) and shape, while commercially available practical grade chitin could not, suggesting that high molecular weight chitin is required for bead-material formation. Supercritical CO2 drying and lyophilization of the wet beads led to dry chitin beads with an opaque appearance, porous interiors, and uniform shape. Loading and release studies of representative active compounds (indigo dye and sodium salicylate) into the chitin beads indicated that the dry beads could be easily loaded from an aqueous solution of active compound and could release 90% of the active compound within 7 h in deionized (DI) water at room temperature.