Long-acting nanoencapsulated arthropod repellent formulations and methods of use thereof

A method for producing a formulations having spherical nanoparticles of matrix type and size less than 500 nm, comprising the steps of:

• (a) preparing a liquid phase comprising a solution of AI+polymer in a solvent or a mixture of solvents to which one or more surfactants may be added;
• (b) preparing a second liquid phase comprising a non-solvent or a mixture of non-solvents to which one or more surfactant may be added, wherein the non-solvent or the mixture of non-solvents should be miscible in all proportions with the solvent or mixture of solvents of the AI;
• (c) adding the liquid phase prepared in (a) to that prepared in (b), or adding the liquid phase prepared in (b) to that prepared in (a), with moderate agitation to produce a colloidal suspension of nanoparticles;
• (d) optionally removing all or part of the solvent or the mixture of solvents and of non-solvent or mixture of non-solvent to make a colloidal nanoparticle suspension of a desired concentration.