Development of Surface Plasmon Resonance-type Quartz Crystal Microbalance and Detection of Interactions of Viomolecules

采用27 MHz压电石英振荡器和矢量网络分析仪，研究了<water><water>生物素化牛血清白蛋白（BSA）、生物素化单链DNA（ssDNA）、生物素化双链DNA（dsDNA）和生物素化普鲁兰多糖（Pullulan）与中性亲和素（NeutrAvidin）固定的27 MHz石英微天平（QCM）板在水溶液、湿空气（97%湿度，-ΔF<wet>和ΔD）<wet>和干空气（-Δ F<air>和Δ D）中的结合过程，得到了共振频率降低（-ΔF）和能量耗散增加（ΔD<air>）的结果。-ΔF_<air>值表示由于这些生物分子的结合而引起的真实的质量变化。聚苯乙烯的值也得到了弹性和疏水膜。（-ΔF）<wet>/（-ΔF）<air>值表明，单位生物分子质量的结合水比率为普鲁兰多糖（2.1- 2.2）&gt; DNA =蛋白质（1.4- 1.6）&gt;聚苯乙烯（1.0）。（-ΔF_<water>）/（-ΔF_<air>）值表明，单位生物分子质量的水动力水（结合水和振动水）比例为dsDNA（6.5）&gt; ssDNA =普鲁兰（3.5- 4.4）&gt;蛋白质（2.4- 2.5）&gt;聚苯乙烯（1.0）。上述值表明，蛋白质的能量耗散主要是由水化引起的，并且蛋白质本身是弹性分子，在水溶液中没有能量耗散。相反，在DNA和普鲁兰多糖的情况下的图相对偏离于用蛋白质观察到的线性的大的水合和能量耗散，这意味着除了由于分子水合的能量耗散之外，由于线性DNA和普鲁兰多糖在水相中的粘弹性而发生大的能量耗散。

By using a 27-MHz piezoelectric quartz oscillator connected with a vector network analyzer, we obtained resonance frequency decreases (-ΔF_<water>) and energy dissipation increases (ΔD_<water>) during binding of biotinylated BSA (bovine serum albumin), biotinylated ssDNA, biotinylated dsDNA, and biotinylated pullulan to a NeutrAvidin-immobilized 27-MHz QCM (quartz crystal microbalance) plate in aqueous solution, as well as in the wet air phase (97% humidity, -ΔF_<wet> and ΔD_<wet>) and in the dry air phase (-ΔF_<air> and ΔD_<air>). The -ΔF_<air> value indicates real mass changes due to the binding of these biomolecules. Values for polystyrene were also obtained as elastic and hydrophobic membranes. In terms of results, (-ΔF_<wet>)/(-ΔF_<air>) values indicated the binding water ratio per unit biomolecular mass were in the order of pullulan (2.1- 2.2) > DNAs = proteins (1.4- 1.6) > polystyrene (1.0). The (-ΔF_<water>)/(-ΔF_<air>) values indicated the hydrodynamic water (binding and vibrating water) ratio per unit biomolecular mass were in the order of dsDNA (6.5)> ssDNA = pullulan (3.5- 4.4) > proteins (2.4- 2.5) > polystyrene (1.0). The aforementioned values suggest that the energy dissipation of proteins was mainly caused by hydration and that proteins themselves are elastic molecules without energy dissipation in aqueous solutions. On the contrary, plots in cases of DNAs and pullulans were relatively deviant toward the large hydration and energy dissipation from the linearity observed with proteins, meaning that the large energy dissipation occurs because of viscoelastic properties of linear DNAs and pullulans in the water phase, in addition to energy dissipation due to the hydration of molecules.