Study On Preparation And Properties Of Quercetin Loaded Nanoparticles Crosslinked By Genipin

Quercetin as the biologically active compound has antioxidative,anti-inflammatory,and anticancer properties among others.However,its disadvantageous properties like insolubility in water and oil,poor stability,and low bioavailability limit its wide application in the health food industry.In this paper,preparation of the nanoparticles was carried out using the antisolvent precipitation method with hydrophobic zein to improve the water solubility and stability of quercetin.and to improve the bioavailability of the load,pectin and chitosan were further used to prepare proteins/polysaccharide nanoparticles with multilayer structure by layer-bylayer electrostatic deposition technology.To further improve the encapsulation efficiency of quercetin,genipin crosslinked nanoparticles were prepared by genipin,at the same time,genipin also exerted antioxidant synergistic effects.In this paper,the effects of chitosan coating and genipin crosslinking on encapsulation efficiency,bioavailability and antioxidant activity of quercetin nanoparticles were clarified,respectively.Then the interaction of genipin and zein was investigated.Finally,the formation mechanism of genipin crosslinked quercetinzein/pectin/chitosan nanoparticles was elucidated.The research contents and results are as follows:The stability,turbidity and zeta-potential were used as index to study the effects of zein/pectin mass ratio on binary nanoparticles and the molecular weight of chitosan on ternary nanoparticles.The results indicates that the binary nanoparticles were more stable when the mass ratio of zein/pectin was 5:3,with smaller average particle size(176.2 nm),PDI(0.221)and high charge(potential-34.2 m V).When the molecular mass of chitosan is 300,000,the stable ternary nanoparticles with smaller average particle size(252.2 nm),PDI(0.254)and high charge(potential +43.2 m V)were prepared.Compared with binary nanoparticles,the chargeability of ternary nanoparticles changes from negative to positive,indicating the formation of multilayer nanoparticles.The binary and ternary nanoparticles were further used to embedded quercetin,and the results showed that,the quercetin encapsulation efficiency increased from 73.3% to 86.6% by replacing half of the pectin coating with chitosan coating.Crosslinking of quercetin-loaded ternary nanoparticles with genipin could further improve the encapsulation efficiency to 92.2%.The introduction of chitosan coating increased the potential of nanoparticles from-34.2 m V to+ 43.5 m V,and the average particle size increased from 155.3 nm to 253.2 nm.The crosslinking of genipin had no influence on the average particle size(243.7 nm)and potential(+45.6 m V)of the nanoparticles.The PDI of all nanoparticles were less than 0.3,the particle size distribution showed a unimodal distribution,which indicated that the nanoparticles were uniform in size.The prepared blank nanoparticles and quercetin nanoparticles were characterized.Scanning electron microscopy images revealed a globular shape of the quercetin nanoparticles.Infrared spectroscopy,fluorescence spectroscopy,circular dichroism and X-ray diffraction patterns analysis showed that the coating of pectin and chitosan were adsorbed to the surface of zein nanoparticles due to the strong electrostatic interaction,which induced fluorescence quenching of the protein,and the hydrophobic structure of the protein was unfolded,so that the random coil were increased by 15%.Genipin changes the secondary structure of zein through a direct crosslinking reaction with the primary amino group of zein,and the disordered regular coil increases by 8%,quercetin loaded into nanoparticles transforms from crystalline state to amorphous state,resulting in hydrophobic and hydrogen bonding interactions with zein.Further gel breaker experiments indicated that electrostatic interactions were the main force maintaining the quercetin nanoparticle.The stability,gastrointestinal digestion,bioavailability and antioxidant activity of quercetin nanoparticles were analyzed.Studies showed that the ionic strength stability of the nanoparticles improved by replacing half of the pectin coating by chitosan coating,which make the nanoparticles can remain stable under the condition of 0～50 mmol/L Na Cl,and less variation in average particle size happened after genipin crosslinking,indicating that genipin crosslinking also had improvement effect on the ionic strength stability to a certain extent.After storage at 4°C and 25°C for 30 days,the quercetin retention rates were 73.5% and 58.3% in the uncrosslinked nanoparticles respectively,while the retention rates of quercetin were78.0% and69.4% in the genipin crosslinked nanoparticles.The storage stability and the oxidation resistance of quercetin nanoparticles were both improved after genipin crosslinking.In addition,controlled release of quercetin in the gastrointestinal environment were realized after embeded in nanoparticles.The bioavailability of quercetin increased from 16.1% to 72.6% after encapsulation,and crosslinking of quercetin nanoparticles with genipin could further improved to it 82.7%.