Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan.
Department of Chemistry and Materials, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan.
J Phys Chem B. 2022 Mar 3;126(8):1787-1798. doi: 10.1021/acs.jpcb.1c10504. Epub 2022 Feb 16.
We investigated the intermolecular dynamics and static structure in the aqueous solutions of lidocaine hydrochloride (LDHCl) in the concentration range of [LDHCl] = 0-2.00 M using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES), small- and wide-angle X-ray scattering (SWAXS), and dynamic light scattering (DLS). For the fs-RIKES experiments, the concentration dependence of the difference low-frequency spectra of the aqueous LDHCl solutions relative to the neat water, which was mainly due to the intermolecular vibrations, was characterized using an exponential function with a characteristic concentration of ∼1 M. For the SWAXS experiments, we observed a manifestation of an excess scattering component centered within a range of 8-10 nm in the aqueous LDHCl solutions. The results of Fourier inversion and further deconvolution analyses unambiguously demonstrated that lidocaines assemble into a nanometer-sized micelle-like structure with the innermost core (∼0.3 nm) and outer shell (∼0.5 nm), respectively. The DLS experiments also found nanometer-sized aggregates and further indicated evidence of the clusters of the aggregates. The results of viscosities, densities, and surface tensions of the solutions and the quantum chemistry calculations supported the unique features of the microscopic intermolecular interaction and the micelle-like aggregation.
我们使用飞秒瑞利诱导克尔效应光谱（fs-RIKES）、小角和广角 X 射线散射（SWAXS）以及动态光散射（DLS）研究了盐酸利多卡因（LDHCl）在水溶液中的分子间动力学和静态结构，浓度范围为[LDHCl] = 0-2.00 M。对于 fs-RIKES 实验，我们用指数函数对水溶液 LDHCl 相对于纯水溶液的低频差光谱的浓度依赖性进行了特征化，该指数函数的特征浓度约为 1 M，这主要归因于分子间振动。对于 SWAXS 实验，我们观察到水溶液 LDHCl 中存在一个突出的散射分量，中心位于 8-10nm 范围内。傅立叶反演和进一步的卷积分析结果明确表明，利多卡因以纳米级胶束样结构聚集，内芯（约 0.3nm）和外壳（约 0.5nm）。DLS 实验还发现了纳米级聚集体，并进一步表明了聚集体簇的证据。溶液的粘度、密度和表面张力以及量子化学计算结果支持了微观分子间相互作用和胶束样聚集的独特特征。
