利用表面力仪（ SFA）研究了单链DNA分子在云母表面的吸附与解吸附特性，获得了在特定缓冲液环境中，云母表面吸附的单链DNA分子层的精确厚度、几何结构及力学特性．首先，通过改变单链DNA的浓度，研究了不同浓度条件下云母表面吸附的单链DNA分子层的几何结构．此外，通过比较不同缓冲液中测得的力距离曲线，研究了单链DNA分子的解吸附行为．结果表明：当单链DNA浓度为100 ng／μL时，其在云母表面吸附形成单分子层，该单分子层的厚度约为1．04 nm；而当10 mmol／L的单价阳离子（ Na＋）加入到缓冲液中时，原本吸附在云母表面的单链DNA分子发生了解吸附现象，进一步分析表明，单价阳离子与高价阳离子之间的竞争效应是引起单链DNA分子解吸附的根本原因．本研究为进一步研究单链DNA分子在无机基底表面的吸附机理提供了实用方法．%An approach for studying the adsorption and desorption behaviors of single-stranded DNA ssDNA molecules on the mica surface by the surface forces apparatus SFA is reported which can be used to characterize the precise thickness configuration and mechanical properties of ssDNA layers on the mica surface at a certain buffer solution. The formation of ssDNA layers is first studied by tuning the ssDNA concentrations and the experimental results indicate that the ssDNA concentration of 100 ng/μL is ideal for forming a ssDNA monolayer structure on the mica surface and the hardwall value measured to be 1.04 nm under this circumstance is regarded as the thickness of the ssDNA monolayer confined on mica. The desorption behavior of ssDNA molecules from the mica surface is further studied by observing and comparing different shapes of the force-distance curves under certain conditions.It is found that the desorption of ssDNA molecules from the mica surface occurs as the monovalent salts are added into the gap buffer.It is inferred that the competition effect between monovalent and divalent salts can induce the release of ssDNA from substrate.The results also reveal that 10 mmol/L monovalent salts Na+ is sufficient for the desorption of ssDNA from mica.This work provides an applicable method to study the binding mechanism of ssDNA molecules on inorganic substrates.
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机译：利用表面力仪（ SFA）研究了单链DNA分子在云母表面的吸附与解吸附特性，获得了在特定缓冲液环境中，云母表面吸附的单链DNA分子层的精确厚度、几何结构及力学特性．首先，通过改变单链DNA的浓度，研究了不同浓度条件下云母表面吸附的单链DNA分子层的几何结构．此外，通过比较不同缓冲液中测得的力距离曲线，研究了单链DNA分子的解吸附行为．结果表明：当单链DNA浓度为100 ng／μL时，其在云母表面吸附形成单分子层，该单分子层的厚度约为1．04 nm;而当10 mmol／L的单价阳离子（ Na＋）加入到缓冲液中时，原本吸附在云母表面的单链DNA分子发生了解吸附现象，进一步分析表明，单价阳离子与高价阳离子之间的竞争效应是引起单链DNA分子解吸附的根本原因．本研究为进一步研究单链DNA分子在无机基底表面的吸附机理提供了实用方法．%An approach for studying the adsorption and desorption behaviors of single-stranded DNA ssDNA molecules on the mica surface by the surface forces apparatus SFA is reported which can be used to characterize the precise thickness configuration and mechanical properties of ssDNA layers on the mica surface at a certain buffer solution. The formation of ssDNA layers is first studied by tuning the ssDNA concentrations and the experimental results indicate that the ssDNA concentration of 100 ng/μL is ideal for forming a ssDNA monolayer structure on the mica surface and the hardwall value measured to be 1.04 nm under this circumstance is regarded as the thickness of the ssDNA monolayer confined on mica. The desorption behavior of ssDNA molecules from the mica surface is further studied by observing and comparing different shapes of the force-distance curves under certain conditions.It is found that the desorption of ssDNA molecules from the mica surface occurs as the monovalent salts are added into the gap buffer.It is inferred that the competition effect between monovalent and divalent salts can induce the release of ssDNA from substrate.The results also reveal that 10 mmol/L monovalent salts Na+ is sufficient for the desorption of ssDNA from mica.This work provides an applicable method to study the binding mechanism of ssDNA molecules on inorganic substrates.
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