| Pathogenic microorganisms can invade the body, cause infection and infectious disease, among them, bacterial and viral infections are the most harmful. Antibiotics antibacterial drugs are the most commonly used to treat the bacterial infection. However, the abuse of antibiotics induced serious damage to the body, accelerated the emergence and spread of drug-resistant bacteria and caused a serious threat to human health. The development of new safe and effective antibacterial agents and looking for new antimicrobial strategies is a huge challenge to human beings. When confronting with respiratory syncytial virus(RSV) infection, which is one of the important pathogens of respiratory tract infection and can trigger bronchiolitis and pneumonia in infants worldwide. So far, there is still no security, economic and effective vaccines or drugs can be used for RSV infection. Curcumin is a natural polyphenolic drug, which has excellent antibacterial, antiviral and other pharmacological activities. However, the poor water solubility and low bioavailability of curcumin limits its clinical application. Silver nanomaterial has the characteristics of broad spectrum resistance pathogenic microorganisms. Graphene oxide has many advantages such as easy preparation, cheap, easy modification and large surface area, and is widely used as a drug carrier and so on. So, we hope to construct a combination of curcumin and nanomaterials as a complex, which has both the pharmacological activity of curcumin and the unique properties of nanomaterials, and can inhibit the infection of pathogenic microorganisms. Therefore, in this paper, we started with curcumin and nanomaterials, prepared new nanomaterials with curcumin functionalization, and analyzed its antimicrobial activity in detail. The main contents of this research are as follows,1. Synthesis curcumin modified silver nanoparticles and analysis its antimicrobial activity(1) Synthesis and characterization of curcumin-AgNPs. We synthesized curcumin-AgNPs(cAgNPs) with using curcumin and silver nitrate as the main raw material and adjusting the reaction temperature up to 100 oC. The as-prepared cAgNPs were uniform, monodisperse, biocompatible and had a plasmon resonance absorption peak at 410 nm. In the reaction system, curcumin played a role both as reducing agent and capping agent. By adjusting the dosage of curcumin, we could obtain different sizes of silver nanoparticles in the range from 10 to 50 nm. Through the analysis of infrared spectra of cAgNPs, curcumin is on the surface of silver nanoparticles and the ketone of curcumin has coordinated with silver, but the hydroxyl groups and methoxy groups of curcumin molecules have been retained. As previously reported, the hydroxyl groups and methoxy groups of curcumin have played important roles in many pharmacological effects. Therefore, we predict that the as-prepared cAgNPs have both the excellent properties of nanoparticles and the pharmacological effects of curcumin. And cAgNPs may have a potiential application prospect in the biochemical analysis and biomedical fields.(2) Analysis the antibacterial activity of curcumin-AgNPs. We choose the Gram-negative bacteria(Escherichia coli) and Gram-positive bacteria(Staphylococcus aureus) as our research subjects to analyze the antibacterial activity of c AgNPs with determining the bacterial survival rate, bacterial growth curve, minimum inhibitory concentration and minimum bactericidal concentration of nanomaterials. The results showed that sizes of cAgNPs affected its antibacterial activity. Through the antibacterial activity analysis of the 12 nm, 20 nm and 30 nm cAgNPs,we found that cAgNPs with 12 nm had the best antibacterial activity, and its minimal inhibitory concentration and minimum bactericidal concentration against Escherichia coli and Staphylococcus aureus was 0.016 nM. This is due to the small particles have large specific surface area and are easy to destroy the cell wall structure of the bacteria, so they have better antibacterial activity than large particles. Compared the antibacterial activity of cAgNPs with the antibacterial activity of citric acid-AgNPs, the capping agent of nanoparticles was also an important influencing factor of the antibacterial activity. The as-prepared cAgNPs showd better antibacterial activity than the citric acid-AgNPs. This was because that cAgNPs had both the pharmacological activity of curcumin and the characteristics of silver nanoparticles. In addition, the cAgNPs also showed good antibacterial activity against the drug resistant strains and its minimal inhibitory concentration was 0.016 nM.(3) Analysis the antiviral activity of curcumin-AgNPs. We took the respiratory syncytial virus as a research model, and explored the antiviral activity of c AgNPs further. Firstly, the morphological changes of the cells were observed by optical microscope. The results showed that c AgNPs could interact with the virions and inhibit the cytopathogenic effect. Then, the TCID50 assay was taken to measure the change of virulence, which was influenced by cAgNPs. As shown, during the neutralization stage, the virus titer of RSV treated with cAgNPs decreased to the virus titer of control group 1/200. The decline was two orders of magnitude. While the virus titer of RSV treated with citric acid-AgNPs decreased to the virus titer of control group 1/9. So, cAgNPs can neutralize with RSV efficiently. Then, the virus titer of RSV decreased to the virus titer of control group 1/19 when the cAgNPs took effect in the prevention of RSV infection. When the cell infected by RSV, the virus titer of RSV decreased to the virus titer of control group 1/13 with using cAgNPs. At last, we used immunofluorescence imaging to further verfy the above results. Based on our results, the as-prepared cAgNPs are expected to develop into a new type of high efficient virucide for respiratory syncytial virus.2. Synthesis curcumin-loaded functionalized graphene oxide and analysis its antiviral activity against respiratory syncytial virus(1) Synthesis curcumin-loaded functionalized graphene oxide. Graphene oxide(GO), as a superstar materials of carbon nanomaterials, has many advantages such as easy preparation, easy modification and good biocompatibility. In addition, GO has large surface area and can be a good drug carrier. Based on this, we performed sulfonic acid and beta cyclodextrin on GO functionalization. The as-prepared functionalized GO could load curcumin efficiently. After modification, the functionalized GO had benign dispersion and its absorption peak position moved from 230 nm to 258 nm. Curcumin could insert into internal cavity of the ?-cyclodextrin, meanwhile, curcumin could interact with GO with π-π stacking interactions. So the functionalized GO had a high load ratio with curcumin and its encapsulation efficiency could reach 65%. This could solve the problem of curcumin insoluble in water.(2) Analysis the antiviral activity of curcumin-loaded functionalized graphene oxide. We analysized the antiviral activity of curcumin-loaded functionalized graphene oxide through observing the change of cell morphology, determination of virus virulence, and analysis the response behavior of cells. Firstly, GO was easy to interact with the virions owing to its large surface area. This could cause respiratory syncytial virus to lose its infectivity efficiently. Secondly, the sulfonate modified with the nanomaterials, similarly to heparin sulfate, could mimick the cell’s surface and combine with respiratory syncytial virus easily, thereby preventing virus adsorption to the cell membrane. Moreover, the functionalized nanomaterials could delivery curcumin into cells and contribute to the prevention of viral replication and budding. The results showed that, during the neutralization stage, the virus titer of RSV decreased to the virus titer of control group 1/24 when the dosage of nanocomposite was 1.25 ?g/ml and the virus titer was undetectable when the concentration of nanocompostie was 2.5 ?g/ml or greater. The decline was four orders of magnitude. When the cells pre-treated with nanocomposite before RSV infection, the virus titer of RSV decreased to the virus titer of control group 1/32 when the dosage of nanocomposite was 2.5 ?g/ml and no detectable RSV were found when the concentration of nanocompostie was 5.0 ?g/ml. While the cells were infected with RSV, the nanocomposite could also have a significant reduction in virus titer. The virus titer of RSV decreased to the virus titer of control group 1/42 when the dosage of nanocomposite was 2.5 ?g/ml and the virus titer was undetectable when the concentration of nanocomposite was 5.0 ?g/ml. The nanocomposite could also inhibit the RSV attachment, the virus titer of RSV decreased to the virus titer of control group 1/42 when the dosage of nanocomposite was 5.0 ?g/ml. In conclusion, the nanocomposites of curcumin-loaded functionalized graphene oxide has highly effective antiviral activity on respiratory syncytial virus infection during the neutralization stage, the prevention stage and the treatment stage without cytotoxicity. It can achieve synergistic antiviral effect of curcumin and nanomaterials. This is expected to provide new insights to develop new antiviral agents and find new virus control strategies.In summary, this research combines curcumin with inorganic nanomaterials together. We synthesized curcumin modified silver nanoparticles, which was uniform, monodisperse, biocompatible and has excellent properties. Then, we investigated its application in resistance to bacterial infection and respiratory syncytial virus infection, and discussed its inhibition mechanism in detail. In addition, new composite nanomaterials was successfully prepared for highly efficient inhibition on RSV infection. The composite nanomaterials was consist of curcumin and functionalized GO, and can inhibit RSV infection with synergistic effect. This can greatly reduce the dosage both of nanomaterials and drugs, and reduce the biological toxicity further. Overall, the two type functionalized inorganic nanomaterials in this paper, are expected to develop into new antimicrobial and antiviral agents, and expand the application of nanomaterials in biomedical field. |
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