Construction Of ZnO Nanoparticles Combined With L-Arginine Controlled Release Drug Delivery System And Its Application In The Treatment Of Breast Cancer

Breast cancer is a major threat to women’s life and health.At present,traditional surgical treatment,radiotherapy and chemotherapy are still the main treatment methods for breast cancer,which are expensive with large side effects on normal tissues and strong drug resistance.L-arginine(L-Arg)has therapeutic effects on many cancers,including breast cancer and its metabolism plays an important role in regulating immune response.Currently,research on the combination of L-Arg is mostly focused on common anticancer drugs such as 5-fluorouracil and doxorubicin.These drugs have low targeting and expensive prices.Therefore,combining L-Arg with low-cost drugs and cell selectivity is a new research direction.Zinc oxide nanoparticles(ZnO NPs)is cheap,safe and has cell selective toxicity.It can kill tumor cells in a certain range while is non-toxic to normal cells.Therefore,this topic explored the possibility of combining L-Arg and ZnO NPs in the treatment of breast cancer.At present,L-Arg is mainly administered orally and its systemic metabolism results in a large dosage.Due to the occurrence of protein corona,there are also some defects in using ZnO NPs directly as drug carriers.Therefore,this topic chose to use thermosensitive hydrogel loaded with L-Arg and ZnO NPs to explore the feasibility of in-situ injection therapy for breast cancer solid tumors.The specific research content is as follows:(1)Explore the possibility of L-Arg combined with ZnO NPs in the treatment of breast cancer.ZnO NPs were synthesized by precipitation method and characterized by their structural characteristics.The results showed that the synthesized ZnO NPs were hexagonal wurtzite structure with a particle diameter of about(106.3 ± 1.4)nm and a polymer dispersity index PDI of 0.214 ± 0.026.Cell experiments have shown that both ZnO NPs and L-Arg can inhibit the proliferation of human breast cancer cells(MCF-7).ZnO NPs at the concentration of 7 μg/mL had no cytotoxicity to human normal breast epithelial cells(MCF-10A)but had a strong killing effect on MCF-7 so this concentration of ZnO NPs and L-Arg were selected for the study of combined drug use.After 48 hours of combined administration,the IC50 of L-Arg decreased from(7.07 ± 0.79)mg/mL to(3.38± 0.38)mg/mL.The combined index(CI)showed that when L-Arg was used with L-Arg at low doses,the two drugs showed antagonistic effects.When LArg was used with L-Arg at higher doses,it was a synergistic effect and the synergistic inhibition increased with the increase of L-Arg dose.When L-Arg was 7.5 mg/mL,the CI index was the smallest,which was a highly synergistic effect.The results of fluorescence staining and flow cytometry showed that the mitochondrial membrane potential was significantly decreased,apoptotic bodies were generated and the apoptotic rate was significantly increased(p<0.05).Western blotting showed that the expression of Bax was increased and the expression of Bcl-2 was decreased.It was proved qualitatively and quantitatively that the combination of drugs could significantly induce the increase of apoptosis of MCF-7.(2)Thermosensitive hydrogel loaded with L-Arg and ZnO NPs for the treatment of breast cancer solid tumors in mice.The optimal ratio of Poloxam hydrogel(P407/P188)was determined to be 22%/3%and had good biosafety.Rheometer results showed that the drug-carrying gel still had good temperature sensitivity,and could maintain good stability at 37℃.In vitro dissolution and drug release experiments showed that the release of L-Arg and ZnO NPs in P407/P188 was mainly related to the dissolution.Staining of live cells showed that all drug loaded gel groups could inhibit the proliferation of MCF-7 and the gel in combination group had the strongest inhibition effect.The results of animal experiments showed that compared with the control group and the single drug group,the tumor growth rate,tumor volume and inhibitory rate were significantly decreased in the combined drug group(p<0.05),the tumor necrotic area was increased,and there was no toxic effect on the heart,liver,spleen and kidney with good safety.