| The comprehensive development and utilization of ginkgo resources has been a hot topic for scholars in forestry,medicine,food,and other fields in recent decades.Much of the ginkgo resources have been explored.However,the ginkgo starch that is rich in ginkgo seeds and kernels has been largely ignored.This research focuses on utilizing the ginkgo starch for nanotechnology in combination with quercetin,a bioactive ingredient that is also abundant in gingko biloba,to prepare and to develop a quercetin nano-loading system based on gingko nano-starch as a carrier.The usage of this nanomedicine is verified in the treatment of cancers,so called one of the three biggest threats to human health.The main research results and discussions are as follows:1.Ginkgo starch nanoparticles were prepared from ginkgo biloba starch using anti-solvent method.The manufacturing parameters—ginkgo starch concentration,anti-solvent addition ratio,and stirring speed—were optimized based on the particle diameter and size distribution of the nanoparticles.With a starch concentration of 0.92 %(W / V),a ratio of water to ethanol of 1: 4.25,and a stirring speed of 447 rpm,the nanoparticle product had a uniform particle size distribution and 152.4±10.48 nm in diameter.According to the results of modern scientific instruments used to study and characterize the appearance and physical and chemical properties of ginkgo starch nanoparticles,the appearance of the granules is spherical or ellipsoidal,and there was a certain aggregation under the observation of transmission electron microscope.The particle size distribution of the three kinds of ginkgo starch nanoparticles was in the range of 50-300 nm.Compared to the raw starch material,the crystal type of the ginkgo starch nanoparticles changed from A-type peak to V-type peak,and crystallinity decreased by varying degrees.Meanwhile,the nanoparticles showed a higher orderliness,and gelatinization temperature was significantly reduced,from about 70 °C to about 45 °C.The endothermic enthalpy during the gelatinization process is reduced from-19.58J/g to-2.76J/g.2.Using the three kinds of ginkgo starch nanoparticles Da Ma Ling,Da Buddha Finger,and Big Fruit Ginkgo biloba and the corn starch nanoparticle as carriers,the SNPs/Qc system was simultaneously prepared by the self-assembly method,and the shape of the system was determined.The appearance,particle size,and drug loading percentage were compared,and the results showed that compared with SNPs,SNPs/Qc loaded were monodispersed and spherical,and there was no obvious aggregation.The loading capacity of Ginkgo nanocarriers was higher than the loading capacity of corn starch.Compared with other natural nanoparticles,the loading capacity of Ginkgo biloba starch particles for Qc was higher than 1.045 mg/mg.In addition,the particle size of SNPs/Qc did not change significantly compared to starch nanoparticles.After the preparation of SNPs/Qc,the SNPs/Qc prepared from Ginkgo biloba starch nanoparticles with the best drug loading effect were used as the research object.The in vitro simulated release characteristics were studied at p H 2.0 and pH 7.4 for the SNPs/Qc.The release curve had three regions,which indicated that Qc exhibits sustained release in artificial gastric fluid(pH 2.0)and intestinal fluid(pH 7.4).It was shown that Ginkgo biloba SNPs could be used as Qc carrier to prepare nano-loading system and have potential as a controlled release nano-carrier for other active ingredients.3.SNPs/Qc made from quercetin loaded in ginkgo starch nanoparticles was studied,carried out in vitro anticancer activity screening,and prepared F127/Qc with FDA-approved polymer material F127 to compare with SNPs/Qc.The results showed that SNPS/Qc had a certain inhibitory activity on five common tumor cells,of which 3LL and HEPG-2 tumor cells had relatively strong inhibitory activity,and the cell activity of the SNPS/Qc nano drug-loading system was slightly lower than F127/Qc.Further experiments on 3LL cells showed that SNPS/Qc could block the cell proliferation cycle in the G2 phase of cell proliferation and increase the proportion of early apoptotic cells to about 33 %.At the same time,the aggregation of two nanocomplexes,SNPs/Qc and F127/Qc,could significantly change the mitochondrial membrane potential of 3LL cells,which was also the reason why 3LL cells showed a significant increase in apoptotic cells.With the increase of the dose of the two,the decrease in mitochondria membrane potential also gradually increased.When the dose was at 25 μg/ mL,the proportion of apoptotic cells reached a maximum of 42.4±1.92 % and 47.68±3.01 %,respectively.The results of Caco-2 single-cell model transmembrane potential measurement showed that the SNPs/Qc nano drug-loading system could open the tight junctions of the cells and enable the nanocomplex enters intestinal epithelial cells through the bypass transport pathway.4.Animal experiments were conducted to explore the anticancer activity of SNPs/Qc.SNPs/Qc was used as the test drug,and a nude mouse model bearing lung cancer cells established in the previous period was used as the test subject.The drug was administered daily by oral feeding for 15 days,and the tumor weight,tumor volume,Mice survival rates were recorded.The results showed that SNPs/Qc had significant antitumor effects in mice.Upon intragastric administration on tumor-bearing mice,SNPs/Qc could successfully arrive at the tumor site and reach the peak of accumulation after 6 hours.It exert the drug effect at the tumor site,resulting in partial apoptosis of tumor cells and loose tumor tissue,inhibited the rapid growth of tumors,making the tumor volume grow slowly,so as to achieve the effect of extending the life cycle of tumor-bearing mice.5.To evaluate the in vivo safety of SNPs/Qc,we tracked body weight of ICR mice,calculated their organ index,measured their blood routine and blood biochemical indicators,and observed morphologies of main organs.It could be seen from the results of the safety evaluation that,with physiological saline as the control group,the SNPs / Qc nanocomposite dose groups did not show significant differences in mouse body weight,organ index,blood biochemical index,and organ morphologies.Therefore,from the results of in vivo and in vitro experiments,we concluded that the nanocomposite has good biocompatibility as an non-toxic oral quercetin carrier with no side effects,and could be widely used as a potential oral drug carrier in biomedicine and other fields. |
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