We present a novel dynamic light scattering setup to probe, with time and space resolution, the microscopic dynamics of soft matter systems confined within millimeter-sized spherical drops. By using an ad-hoc optical layout, we tackle the challenges raised by refraction effects due to the unconventional shape of the samples. We first validate the setup by investigating the dynamics of a suspension of Brownian particles. The dynamics measured at different positions in the drop, and hence different scattering angles, are found to be in excellent agreement with those obtained for the same sample in a conventional light scattering setup. We then demonstrate the setup capabilities by investigating a bead made of a polymer hydrogel undergoing swelling. The gel microscopic dynamics exhibit a space dependence that strongly varies with time elapsed since the beginning of swelling. Initially, the dynamics in the periphery of the bead are much faster than in the core, indicative of non-uniform swelling. As the swelling proceeds, the dynamics slow down and become more spatially homogeneous. By comparing the experimental results to numerical and analytical calculations for the dynamics of a homogeneous, purely elastic sphere undergoing swelling, we establish that the mean square displacement of the gel strands deviates from the affine motion inferred from the macroscopic deformation, evolving from fast diffusive-like dynamics at the onset of swelling to slower, yet supradiffusive, rearrangements at later stages.
Biocompatible Microscale DNA Hydrogels with Programmable Swelling and Sequence-Specific Dissolution
Johns Hopkins University（约翰斯·霍普金斯大学）；Johns Hopkins University School of Medicine（约翰斯·霍普金斯大学医学院）；The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Hospital（约翰斯·霍普金斯医院西德尼·基梅尔综合癌症中心）
Non-uniform swelling of polyelectrolyte hydrogels: effects of charge regulation
Wenzhou University（温州大学）；Zhejiang Key Laboratory of Soft Matter Biomedical Materials, Wenzhou Institute, University of Chinese Academy of Sciences（中国科学院大学温州研究院软物质生物医用材料浙江省重点实验室）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；School of Physics and Astronomy, & Center for Physics and Chemistry of Living Systems, Tel Aviv University（特拉维夫大学物理与天文学学院及生命系统物理化学中心）；School of Sino-German Engineering, Shanghai Technical Institute of Electronics and Information（上海电子与信息工程技术学院中德工程学院）
