Blueberry‑inspired starch nanospindles engineered for edible films with integrated UV‑shielding and antimicrobial functions

This study reports a biomimetic design of starch-based nanospindles (ASP) for fabricating multifunctional edible films with enhanced UV-blocking and anti-biofilm properties. Inspired by the waxy epidermis of blueberries, ASP were synthesized via an anti-solvent method. A key finding is that increasing short-chain glucan concentration from 10 to 100 mg/mL enlarged ASP’s width from 105 to 228 nm, while the length remained relatively stable (~ 404–460 nm). Notably, 20ASP (width: ~130 nm, length: ~420 nm) exhibited ~ 80% UV-blocking efficiency with high visible-light transmittance, demonstrating nanospindle dimensions critically determine light management properties. Further modification with octenyl succinic anhydride (OASP) enhanced hydrophobicity (contact angle > 72.1°). The OASP-incorporated alginate films (O-AlF) demonstrated superior barrier properties (water vapor permeability reduced by 49%, oxygen permeability by 75%), strong anti-biofilm activity against Staphylococcus aureus (76.4% inhibition) and Escherichia coli (63.8% inhibition), and excellent biocompatibility (cell viability > 90%). The derivative thermogravimetric curve of AlF exhibits two distinct peaks at 81 ℃ and 203 ℃ while O-AlF shows these peaks at higher temperatures of 145 ℃ and 220 ℃, respectively, with the total mass loss increasing from 19.6% to 26.2%. After UV irradiation, the mechanical parameter of O-AlF was even 28.13 times higher than AlF. In cherry tomato preservation, O-AlF effectively delayed spoilage, reduced weight loss, retained titratable acidity (only 0.03% reduction), effectively delayed decay and reduced nutrient loss, with weight loss reduced by 1.35% compared to AlF, ascorbic acid loss rate reduced by 17.2% and better retained ascorbic acid (19.2% loss vs. 36.3% in control). These results demonstrate that structure–function–optimized O-AlF film provides a sustainable, multifunctional coating for extending fruit shelf life through synergistic UV protection, barrier enhancement, and antibacterial activity.