Stability And Cellular Uptake And Absorption Of Bovine Serum Albumin-Quercetin Nanoparticles

Study of formation, stability and absorption of bovine serum albumin (BSA)-quercetin (QUE) nanoparticles will help us understand the interaction mechanisms, nanoparticle formation and bioavailability of macromolecules and small molecules. The comparative study was carried out on the interaction and nanoparticle formation of BSA-QUE or BSA and anthocyanin (ACN). The influence of pH, time, temperature and chemical modification on stability of BSA-QUE nanoparticles was also investigated. Furthermore, the bioactivities of BSA-QUE nanoparticles were studied, including cell growth inhibition, cellular uptake and absorption of BSA-QUE nanoparticles.QUE had a great ability to quench BSA’s fluorescence in both static and dynamic modes, and hydrophobic interaction played a dominant role for BSA and QUE interaction. ACN could quench BSA’s fluorescence in static mode, and hydrogen bond and Van der Waals force played a dominant role for BSA and ACN interaction. BSA interacted with QUE or ACN and formed BSA-QUE/ACN nanoparticles. The binding force between BSA and QUE was stronger than that between BSA and ACN, and BSA-QUE nanoparticles were more stable than BSA-ACN nanoparticles. The average diameter of BSA-QUE and BSA-ACN were42.53nm and53.68nm, respectively. The Zeta potentials of BSA-QUE and BSA-ACN were-25.64mV and-21.50mV respectively. The free radical scavenging rates of QUE or ACN were lower when QUE or ACN interacted with BSA. While the phenolic hydroxyl groups of QUE and ACN could involve in the interaction with BSA, which would masked some of antioxidant activity of QUE and ACN.No characteristic absorption band observed for QUE, and two absorption bands appeared for BSA-QUE in pH2.5,5.0and6.0. Three absorption bands observed for QUE and BSA-QUE in pH7.4and8.0. BSA and QUE interaction led to formation of BSA-QUE nanoparticle with size less than10run, along with some micro-particles with size more than100nm under different pH conditions. While the micro-particles were more in acid solutions than in neutral and alkaline solutions. The DPPH and ABTS radical scavenging rates of QUE interacted with BSA were lower than that of the QUE, and the lowering degree was smaller in alkaline solutions than in acid solution. With the increasing temperature and time, the percent of nanoparticles with diameter less than50nm was decreased. BSAreducing by cysteine (cBSA) interacted with QUE and formed cBSA-QUE nanoparticles, which improved the binding capacities of BSA with QUE.With the increasing time and concentrations of QUE and BSA-QUE, the cell viability of Caco-2was decreased. When the incubation time was1h, the cell viability of Caco-2was decreased from100%to79.52%and84.26%with the increasing concentration of QUE and BSA-QUE, respectively. When the incubation time was2h, the cell viability of Caco-2was decreased from100%to68.65%and61.54%. When the incubation time was3h, the cell viability of Caco-2was decreased from100%to49.04%and41.73%. The lactate dehydrogenase release (LDH) of Caco-2were108.05%,196.55%and274.71%when BSA-QUE incubated with cells for1h,2h and3h, respectively. Compared with the control, the cell incubation with BSA-QUE at G1period was more; the cell at G2period was decreased; there was no significant change of cell at S period, which was decreased significantly at3h. Compared with the control, the early and late apoptosis of cell incubation with BSA-QUE was increased from9.38%to24.59%and from0.06%to15.94%with the extension of time, respectively.Cellular uptake of BSA-QUE nanoparticles were distributed in the nucleus. The fluorescence intensity near the nucleus was stronger with the extension of time. In the Caco-2cell monolayer absorption process, the content of QUE in well was increased with the extension of time. When Caco-2cell monolayer was incubated with BSA-QUE, QUE content in the well was increased significantly from0min to180min. There was no significant difference between QUE and BSA-QUE in the absorption at the first30min. The content of QUE in the well incubated with BSA-QUE was more than that of QUE from30min to180min.