Thermal and structural characteristics of novel V-type starch nanoparticles synthesized via the H2O2/UV synergistic recrystallization approach

Abstract

Unlike the traditional nanoprecipitation method, this study introduced a novel methodology for fabricating V-type starch nanoparticles. The short-chain starch, derived from a synergistic treatment involving H₂O₂ and UV light, was recrystallized to synthesize a novel class of V-type chestnut starch nanoparticles. Furthermore, the study explored the influence of varying pH conditions on the efficacy of the H₂O₂ and UV treatment, as well as their subsequent effects on properties of the starch nanoparticles. The results showed that H₂O₂ and UV treatment effectively degrade starch into short chains (DP < 37), with pH significantly influencing chain fragmentation and oxidation. With the exception of when the pH was 11, starch chains (13 < DP < 24) accounted for over 60 %. However, when the pH was 11, the proportion of starch chains (DP < 5) increased sharply to 36.12 %. At a pH of 7, the highest carboxyl content (6.65 COOH/100GU) was observed. Starch nanoparticles synthesized from short-chain starch exhibited uniform spherical morphology, and at a pH of 5, these particles achieved the smallest and most uniform size (50–70 nm). FTIR results indicated that the hydrogen bonding between short-chain starch molecules was enhanced after treatment. X-ray diffraction analysis revealed that the starch nanoparticles possessed a V-type crystalline structure. These nanoparticles displayed excellent thermal stability, with peak gelatinization temperatures above 100 °C. Notably, the peak gelatinization temperature reaches 119.83 °C at a pH of 5, highlighting their superior thermal properties as bio-based macromolecular materials. This study offered valuable insights into oxidized starch nanoparticle preparation and nano-carrier development.