Alginate/cashew gum floating bead as a matrix for larvicide release

A polymeric floating system composed of Alginate (ALG) and Cashew gum (CG), loaded with an essential oil (Lippia sidoides–Ls) was prepared by ionotropic gelation, characterized regarding its physical-chemistry properties and evaluated on its potential as a controlled release system. The influence of process parameters on the buoyancy, loading, swelling and in vitro and in vivo release kinetics, was investigated. Results showed that beads produced with carbonate and Ls at high level contents exhibit good floatability (up to 5 days) and loading capacity (15.2–23.8%). In vitro release data showed a Fickian diffusion profile and in vivo experiments showed that ALG–CG floating system presented a superior and prolonged larvicide effect, in comparison with non-floating ones, presenting larvae mortality values of 85% and 33%, respectively, after 48 h. These results indicate that ALG–CG floating beads loaded with Ls presented enhanced oil entrapment efficiency, excellent floating ability, and suitable larvicide release pattern.

► This work highlights the use of floating beads for larvicide release.
► Beads were made of alginate and a natural, inexpensive and abundant biopolymer (cashew gum).
► The system exhibit good floatability and moderate loading capacity (15.2–23.8%).
► Mortality figures were circa three times greater than that obtained by non-floating beads.