Starch nanoparticle preparation by the nanoprecipitation technique: Effects of formulation parameters

This study investigates how key formulation parameters influence the formation of starch nanoparticles using the nanoprecipitation technique. When loaded with different compounds, starch nanoparticles present a promising option for controlled drug delivery in food, biomedical, and pharmaceutical applications. The work thoroughly examines factors such as polymer concentration, NaOH concentration, solvent ratios, stirring speed, injection flow, and properties of the non-solvent phase. Characterization is conducted using dynamic light scattering, laser Doppler electrophoresis, and scanning electron microscopy, followed by statistical analysis. Increasing the stirring speed notably decreases nanoparticle size, yielding dimensions of 161.5±2.1 nm, 157.6±2.5 nm, and 136.0±0.8 nm at 500, 700, and 900 rpm, respectively. Higher starch concentrations slightly increase the zeta potential of starch nanoparticles to values of −1.97±0.4 mV, −3.1±0.7 mV, and −3.9±1.5 mV for concentrations of 0.5 %, 1 %, and 2 %, respectively. This charge can be attributed to the hydroxyl functional groups in starch monomers. The study also assesses the stability of starch nanoparticles at different pH levels (4, 7.4, and 9) and explores the use of cryoprotectants during freeze-drying. Remarkably, nanoparticles show enhanced stability at pH 7.4, maintaining their initial sizes over six weeks. Cryoprotectants, even in small amounts, effectively preserve nanoparticle size post-freeze-drying. By adjusting formulation parameters, researchers can tailor the physicochemical characteristics of nanoparticles to achieve specific sizes and ensure stability.