Atomic force microscopy (AFM) was used to study the competitive adsorption betweenbovine serum albumin (BSA) and type Ⅰ collagen on hydrophilic and hydrophobic silicon wafers.BSA showed a grain shape and the type Ⅰ ...Atomic force microscopy (AFM) was used to study the competitive adsorption betweenbovine serum albumin (BSA) and type Ⅰ collagen on hydrophilic and hydrophobic silicon wafers.BSA showed a grain shape and the type Ⅰ collagen displayed fibril-like molecules with relativelyhomogeneous height and width, characterized with clear twisting (helical formation). These AFMimages illustrated that quite a lot of type Ⅰ collagen appeared in the adsorption layer on hydrophilicsurface in a competitive adsorption state, but the adsorption of BSA was more preponderant than thatof type Ⅰ collagen on hydrophobic silicon wafer surface. The experiments showed that theinfluence of BSA on type Ⅰ collagen adsorption on hydrophilic surface was less than that onhydrophobic surface.展开更多
The interaction between ribosome-inactivating proteins (RIPs) and supercoiled DNA was observed with an atomic force microscope (AFM). It was found that RIPs can bind to both supercoiled DNA and the unwound double stra...The interaction between ribosome-inactivating proteins (RIPs) and supercoiled DNA was observed with an atomic force microscope (AFM). It was found that RIPs can bind to both supercoiled DNA and the unwound double stranded loop region in supercoiled DNA. The RIPs hound to the supercoils can induce the conformational change of supercoiled DNA. Furthermore, the supercoiled DNA was relaxed and cleaved into nick or linear form by RIPs. It indicated that RIP seemed to be a supercoil-dependent DNA binding protein and exhibited the activity of su-percoil-dependent DNA endonuclease.展开更多
An experimental and statistical study was carried out to explore the effects of mechanical forces on the ends of linear double-stranded DNA (dsDNA) fragments. Mechanical force was applied onto individual DNA molecules...An experimental and statistical study was carried out to explore the effects of mechanical forces on the ends of linear double-stranded DNA (dsDNA) fragments. Mechanical force was applied onto individual DNA molecules during atomic force microscope (AFM)-based picking-up manipulation. By comparing the PCR efficiency of two DNA fragments with primers either at ends or at the inner regions, it was found that the ends of DNA fragments were damaged during picking-up process.展开更多
Many environmental factors can cause DNA damage, such as radiation, heat, oxygen free radical, etc., which can induce mutation during DNA replication. Meanwhile, DNA molecules are subjected to various mechanical force...Many environmental factors can cause DNA damage, such as radiation, heat, oxygen free radical, etc., which can induce mutation during DNA replication. Meanwhile, DNA molecules are subjected to various mechanical forces in numerous biological processes. However, it is unknown whether the mechanical force would induce DNA damage and introduce mutation during DNA replication. With the combination of single-molecule manipulation based on atomic force microscopy (AFM), single molecular polymerase chain reaction (SM-PCR) and Sanger's sequencing, we investigated the effect of mechanical force on DNA. The results show that mechanical force can cause DNA damage and induce DNA mutation during amplification.展开更多
DNA is a kind of promising molecule as nano-lead to build or connect nano-devices due to its stable linear structure and certain conductivity. Many methods have been applied to constructing nano-patterns by using DNA ...DNA is a kind of promising molecule as nano-lead to build or connect nano-devices due to its stable linear structure and certain conductivity. Many methods have been applied to constructing nano-patterns by using DNA molecule. In this report it is presented that l-DNA was aligned on Si substrate by using the free-flowing method and then imaged by an atomic force microscope (AFM). After the second liquid flow, a catenary-like pattern and a crossed network of l-DNA were formed. In addition, the alignedl-DNA was successfully cut off by tips of AFM.展开更多
DNA/octadecylamine(ODA) monolayers were transferred onto silicon substrates and the morphologies of the monolayers were investigated by Atomic Force Microscope(AFM). AFM images show that the morphologies of DNA dissol...DNA/octadecylamine(ODA) monolayers were transferred onto silicon substrates and the morphologies of the monolayers were investigated by Atomic Force Microscope(AFM). AFM images show that the morphologies of DNA dissolved in pure water are very different from those of DNA dissolved in the NaCl solution. When DNA molecules are dissovled in pure water, they will form ball-like structure in the monolayer. When the DNA molecules are dissolved in NaCl solution, they will form bunch lines. This DNA line offers a valuable template to direct the formation of unique inorganic nanomaterials.展开更多
文摘Atomic force microscopy (AFM) was used to study the competitive adsorption betweenbovine serum albumin (BSA) and type Ⅰ collagen on hydrophilic and hydrophobic silicon wafers.BSA showed a grain shape and the type Ⅰ collagen displayed fibril-like molecules with relativelyhomogeneous height and width, characterized with clear twisting (helical formation). These AFMimages illustrated that quite a lot of type Ⅰ collagen appeared in the adsorption layer on hydrophilicsurface in a competitive adsorption state, but the adsorption of BSA was more preponderant than thatof type Ⅰ collagen on hydrophobic silicon wafer surface. The experiments showed that theinfluence of BSA on type Ⅰ collagen adsorption on hydrophilic surface was less than that onhydrophobic surface.
基金Project supported by the National Natural Science Foundation of China, Chinese Academy of Sciences and Shanghai Center of Life Sciences.
文摘The interaction between ribosome-inactivating proteins (RIPs) and supercoiled DNA was observed with an atomic force microscope (AFM). It was found that RIPs can bind to both supercoiled DNA and the unwound double stranded loop region in supercoiled DNA. The RIPs hound to the supercoils can induce the conformational change of supercoiled DNA. Furthermore, the supercoiled DNA was relaxed and cleaved into nick or linear form by RIPs. It indicated that RIP seemed to be a supercoil-dependent DNA binding protein and exhibited the activity of su-percoil-dependent DNA endonuclease.
基金Supported by the Major State Basic Research Development Program in China (No.2007CB936000)Chinese Academy of Sciences (No. KJCX2-EW-N03)National Science Foundation of China (Nos.10975175, 90923002, 21073222 and 10874198)
文摘An experimental and statistical study was carried out to explore the effects of mechanical forces on the ends of linear double-stranded DNA (dsDNA) fragments. Mechanical force was applied onto individual DNA molecules during atomic force microscope (AFM)-based picking-up manipulation. By comparing the PCR efficiency of two DNA fragments with primers either at ends or at the inner regions, it was found that the ends of DNA fragments were damaged during picking-up process.
基金Supported by National Basic Research Program of China(973 Program Nos.2007CB936000 and 2012CB932600)National Natural Science Foundation of China(No.21073222)Chinese Academy of Sciences(No.KJCX2-EW-N03)
文摘Many environmental factors can cause DNA damage, such as radiation, heat, oxygen free radical, etc., which can induce mutation during DNA replication. Meanwhile, DNA molecules are subjected to various mechanical forces in numerous biological processes. However, it is unknown whether the mechanical force would induce DNA damage and introduce mutation during DNA replication. With the combination of single-molecule manipulation based on atomic force microscopy (AFM), single molecular polymerase chain reaction (SM-PCR) and Sanger's sequencing, we investigated the effect of mechanical force on DNA. The results show that mechanical force can cause DNA damage and induce DNA mutation during amplification.
基金This work was supported by the State Key Basic Research and Development Project(Grant No.199801012).
文摘DNA is a kind of promising molecule as nano-lead to build or connect nano-devices due to its stable linear structure and certain conductivity. Many methods have been applied to constructing nano-patterns by using DNA molecule. In this report it is presented that l-DNA was aligned on Si substrate by using the free-flowing method and then imaged by an atomic force microscope (AFM). After the second liquid flow, a catenary-like pattern and a crossed network of l-DNA were formed. In addition, the alignedl-DNA was successfully cut off by tips of AFM.
文摘DNA/octadecylamine(ODA) monolayers were transferred onto silicon substrates and the morphologies of the monolayers were investigated by Atomic Force Microscope(AFM). AFM images show that the morphologies of DNA dissolved in pure water are very different from those of DNA dissolved in the NaCl solution. When DNA molecules are dissovled in pure water, they will form ball-like structure in the monolayer. When the DNA molecules are dissolved in NaCl solution, they will form bunch lines. This DNA line offers a valuable template to direct the formation of unique inorganic nanomaterials.
文摘为改善低盐(1g/100mLNaCl)环境中肌原纤维蛋白的功能特性,研究不同添加量的焦磷酸钠(tetrasodium pyrophosphate,TSPP)、三聚磷酸钠(sodium tripolyphosphate,STPP)、六偏磷酸钠(sodium hexametaphosphate,SHMP)对白鲢鱼肌原纤维蛋白结构和功能特性的影响。结果表明:低盐条件下,随着磷酸盐添加量的增加,肌原纤维蛋白的溶解度、表面疏水性、乳化性均呈上升趋势;3种磷酸盐均使肌原纤维蛋白引入磷酸基团;添加0.2~0.5 g/100 mL STPP能够降低肌原纤维蛋白热解速率,提升蛋白质热稳定性,其中0.4 g/100 mL STPP修饰的蛋白质磷酸化程度最大,此时大量的磷酸根基团与肌原纤维蛋白结合;TSPP和STPP更有利于蛋白质的聚集,而SHMP磷酸化的蛋白质更稳定。综上,0.4 g/100 mL STPP对低盐条件下肌原纤维蛋白功能特性具有更好的改善作用。
