| Gold nanoparticles show a wide range of great characteristics due to their miniscule size, which is significantly different from gold chunks and gold ions. They have large surface areas, unique localized surface plasmon resonance, and adjustable properties, which make them widely used in biological, chemical, medicine, and other fields. At present, gold nanoparticles play a huge role in the detection of cancer-related genes and load anticancer drugs, which can achieve the goal of detection and treatment at the same time. In addition, they play a secondary role in antibacterial and protecting damaged nerve cells. This article base on that gold nanoparticles to construct a novel nano-antioxidant and give a deep research on it.We use a classical method of using citric acid sodium to reduce hydrogen tetrachloroaurate hydrate to produce 18 nm gold nanoparticles(Au Nanoparticles 2, Au NPs2) and a 5 nm sodium thioglycollate-stabilized gold nanoparticles(Au Nanoparticles 1, Au NPs1). Through ultraviolet–visible spectroscopy, Malvern laser particle size and transmission electron microscopy, we know that both those two kind of gold nanoparticles are highly stabilized and uniform in size. We designed a novel antioxidant with Au NPs and maize protein Leu-Asp-Tyr-Glu(TPM) and made the TPM Leu-terminal to add a 3-Mercaptopropionic acid and to construct a new complex 3-Mercaptopropionic acid–Leu-Asp-Tyr-Glu(MPA-TPM), which can self-assemble into gold nanoparticles’ surfaces through-SH. From the Fourier Transform Infrared Spectroscopy(FT-IR) we could know that the MPATPM was connected with Au NPs through –SH and formed a new Au-peptide complex(Au NPs@MPATPM). Through ABTS+,a tool to test total anti-oxidation capacity, determined that Au NPs1@MPATPM can reach 48.87% than control. To scavenging superoxide anion free radical that Au NPs2@MPATPM can reach 51.58%. We use MTT method to detect the cell toxicity also show that both Au NPs1 and Au NPs2 are nontoxic of Hela cells. The nano-antioxidant can be significantly useful for protection Hela cell from hydrogen peroxide induced damage.Furthermore, we apply C. elegans as a model organism to test gold nanoparticles antioxidant activity under oxidation stress which induced by j uglone. The result show that not only the nano-antioxidant can enhance the life span of C. elegans under stress,but also can enhance the life span of C. elegans under normal environment. In addition, the research show that both the nanoparticles and the nano-antioxidant can improve SOD activity in CF1553(mu Is84). The nano-antioxidant which functioned with MPATPM can improve SOD activity in CF1553 than gold nanoparticles.As expected, antioxidant ability of Au NPs@MPATPM was much higher than that of the MPATPM monomer. A comparative analysis of the spectral characteristics of Au NPs@MPATPM and the MPATPM monomer further implied that the enhancement of the antioxidative activity may be ascribed to the variation in the transition state for the free radical scavenging reaction through increase the interactions among adjacent groups near the surface of Au NPs@MPATPM, especially have enhanced the phenolic hydroxyl group activity which is a main group in antioxidant.Overall, we successfully synthesized two kinds of monodispersed gold nanoparticles with diameters of 5 nm(Au NPs1) and 18 nm(Au NPs2). Additionally, based on those two kinds of gold nanoparticles and MPATPM we designed and constructed two nano-antioxidants which are Au NPs1@MPATPM and Au NPs2@MPATPM. In vitro and in vivo experiments show that both Au NPs1@MPATPM and Au NPs2@MPATPM have a certain antioxidative activities and can enhance the life span of C. elegans under oxidative stress. This research is highly practical for nano-antioxidant development. |
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