Effect of advanced multi-frequency pulsed ultrasound on improving stability, bioavailability, and antioxidant activity of quercetin loaded by maize peptide nanoliposomes

• Multi-frequency ultrasound (UT) enhanced encapsulation efficiency of nanoliposomes • UT rose Qu & MP embedding rates (47.09% & 39.07%) and reduced particle size by 33.12% • UT treatment increased liposome stability and enhanced Qu solubility (1.56 times) • UT treatment enhanced digestive and intracellular antioxidant activity (3.92 times) • UT activated cellular transport pathway and increased Qu bioavailability by 28.22% To enhance the encapsulation efficiency, stability, bioavailability, and antioxidant activity of quercetin (Qu), an advanced physical processing technology of multi-frequency pulsed ultrasound was employed to prepare Qu-loaded maize peptide (MP) nanoliposomes (UT complex Lipo). The effects of preparation parameters on encapsulation efficiency were evaluated, along with the influence of ultrasonic-assisted co-encapsulation on the structure, functional properties, stability, and cellular uptake. The results demonstrated that ultrasonic treatment significantly improved the Qu and MP embedding rates (47.09% and 39.07%), yield (8.97%), DPPH scavenging activity (27.01%), emulsifying activity index (48.72%), stability index (4.00%), and Qu solubility (1.56-fold increase) in the nanoliposome. Additionally, the treatment reduced the mean particle diameter by 33.12%, through the de-folding and de-spiraling of the molecular structure, compared to the unsonicated sample. Moreover, compared to the monomeric forms of Qu and MP, ultrasonic-assisted encapsulation markedly enhanced nanoliposome stability under prolonged storage, high temperatures, high salt concentrations, and gastrointestinal digestion. The retention rates of Qu and MP post-digestion were 40.88% and 31.67%, respectively. Furthermore, this technology substantially increased the cellular absorption rate, transport rate, and bioavailability of Qu by 22.71%, 27.17% and 28.22%, respectively, at a dosage of 0.4 mg/mL, which was attributed to the significant downregulation of mRNA expression levels of tight junction proteins, Zonula occludens-1 (ZO-1) and Occludin. Moreover, UT enhanced the intracellular antioxidant capacity of Qu by 3.92 times. These findings provide insights into the molecular mechanisms underlying antioxidant activity protection and their interaction with ultrasonic treatment. This study presents a promising approach of ultrasonic-assisted co-encapsulation for the efficient oral delivery of active ingredients, thereby enhancing their biological activity.