*4.2.2 Emulsion evaporation*

Polymeric nano-emulsions are formulated whereby organic solvent is added to a solution of chitosan with surfactant and mixed via sonication [93]. Basically, the emulsion droplets are converted into NP suspension as the organic solvent evaporates by continuous magnetic stirring at room temperature. The NP suspensions are then centrifuged, washed with distilled water to remove additives such as surfactants and finally lyophilized [94]. Poovi et al. encapsulated the poorly water-soluble drug, repaglinide, into chitosan NP using the emulsion evaporation for sustained release. They proved that the NP exhibited a controlled release of repaglinide and obtained a high drug loading (11.22% w/w) and encapsulation efficiency (97.0%) [95]. In another study, Lee et al. employed solvent evaporation method to formulate polymeric NP from chitosan derivatives fluorescein isothiocyanate (FITC) - conjugated glycol CSs (FGCs) using diluted chloroform as the solvent. Size range of 150–500 nm were obtained and the NP remained stable in phosphate buffered saline for 20 days at 37°C [96].
