Green preparation of small-sized starch nanoparticles using nanoprecipitation

Starch nanoparticles (sNPs) are attractive for numerous applications due to their non-toxicity, environmentally friendly nature, readily available raw materials worldwide, and biodegradability. However, the heterogeneous nature of starch makes it a challenge to prepare homogeneous sNP. The lack of existing preparation methods for small-sized sNPs (ss-sNPs) with high quality has been limiting their practical applications. In this study, we have developed a new method by combining nanoprecipitation and successive centrifugation to generate ss-sNPs with well-defined properties from six different starch types. The method is simple, environmentally friendly, requires a relatively short processing time (<4 h) and generated sizes smaller than 50 nm diameter. The products were thoroughly investigated, structurally, microscopically, and physically. The ss-sNPs products derived from all starch types demonstrated high stability in water (up to three weeks), meeting the requirements for practically any application. The formation of near monodisperse 10 nm diameter ss-sNPs was achieved using a high amylose (more linear) starch type as starting material. However, all ss-sNPs were mainly comprised of short-chained amylopectin. This general and efficient method for producing ss-sNPs offers significant opportunities for their application in various fields.