Green preparation and characterisation of waxy maize starch nanoparticles through enzymolysis and recrystallisation

• Starch nanoparticles were prepared through debranching, retrogradation with waxy corn starch.
• Nanoparticles obtained by freeze drying.
• The particle diameters decreased from several μm to about 60–120 nm.
• The yield of nanoparticles increased above 85%.
• The nanoparticles had the relative crystallinity at 55.41%.

Waxy maize starch was treated by a facile and green enzymolysis procedure to fabricate starch nanoparticles (StNPs). The yield of StNPs was raised to 85% by pullulanase treatment, and the preparation duration was two days. Morphology (SEM, TEM), crystalline structure (XRD), thermal gravimetry analysis (TGA), and the group changing (FTIR) of StNPs prepared with different starch concentrations (10%, 15%, 20% and 25%, w/v) were investigated. Compared with native starch, the topography of all StNPs exhibited irregularly-shaped fragments, the particle diameters decreased from several μm to about 60–120 nm, and the crystal pattern changed from A-type to B + V-type. The StNPs prepared with 15% starch slurry had the highest degree of crystallinity at 55.41%. The eco-friendly prepared nanoparticles could be widely used in biomedical applications and development of new materials.