Most binary superlattices created using DNA functionalization or other approaches rely on particle size differences to achieve compositional order and structural diversity. Here we study two-dimensional (2D) assembly of DNA-functionalized micron-sized particles (DFPs), and employ a strategy that leverages the tunable disparity in interparticle interactions, and thus enthalpic driving forces, to open new avenues for design of binary superlattices that do not rely on the ability to tune particle size (i.e., entropic driving forces). Our strategy employs tailored blends of complementary strands of ssDNA to control interparticle interactions between micron-sized silica particles in a binary mixture to create compositionally diverse 2D lattices. We show that the particle arrangement can be further controlled by changing the stoichiometry of the binary mixture in certain cases. With this approach, we demonstrate the abil- ity to program the particle assembly into square, pentagonal, and hexagonal lattices. In addition, different particle types can be compositionally ordered in square checkerboard and hexagonal - alternating string, honeycomb, and Kagome arrangements.
Direct measurement of DNA-mediated adhesion between lipid bilayers
可变形介观单元之间的多价相互作用在生物学中是普遍存在的，其中膜大分子介导相邻活细胞之间以及细胞与固体基质之间的相互作用。最近，类似的人工材料已经通过用选择性接头，特别是短DNA序列官能化顺应性布朗单元（例如乳液液滴和脂质囊泡）的外表面来合成。这一发展扩大了DNA作为选择性胶水的适用范围，最初适用于固体纳米和胶体颗粒。在非常可变形的脂质囊泡上，多价相互作用的统计效应和膜的机械变形之间的耦合引起复杂的涌现行为，正如我们最近所证明的[Parolini et al.，Nature Communications，2015，6，5948]。在这些系统中观察到的复杂现象学的几个方面仍然缺乏定量的实验表征和基本的理解。在这里，我们专注于DNA介导的多价相互作用的一个单一的脂质体粘附到一个平坦的支持双层。这种简化的几何形状使得能够估计由作用于脂质体的DNA介导的粘附力引起的膜张力。我们的实验研究完成了形态学测量和表征的DNA熔融过渡，探测原位福斯特共振能量转移光谱。实验结果进行了比较与分析理论的预测，耦合的囊泡的变形的移动连接器的统计力学的完整描述。最多只有一个拟合参数，我们的理论能够半定量地匹配实验数据，确认基本假设的质量。
Condensation of hundreds of mega-base-pair-long human chromosomes in a small nuclear volume is a spectacular phenomenon. This process is driven by the formation of chromosome loops. ATP consuming motor, condensin, interacts with chromatin segments to actively extrude loops. Motivated by real-time imaging of loop extrusion (LE) and measurements using magnetic tweezer experiments, we created an analytically solvable model, predicting the LE velocity and step size distribution as a function of external load. The theory fits the experimental data quantitatively, and suggests that condensin must un…
DNA-mediated multivalent interactions between colloidal particles have been extensively applied for their ability to program bulk phase behaviour and dynamic processes. Exploiting the competition between different types of DNA-DNA bonds, here we experimentally demonstrate the selective triggering of colloidal self-assembly in the presence of a functionalised surface, which induces changes in particle-particle interactions. Besides its relevance to the manufacturing of layered materials with controlled thickness, the intrinsic signal-amplification features of the proposed interaction scheme mak…
The self-assembly of DNA-coated colloids into highly-ordered structures offers great promise for advanced optical materials. However, control of disorder, defects, melting, and crystal growth is hindered by the lack of a microscopic understanding of DNA-mediated colloidal interactions. Here we use total internal reflection microscopy to measure in situ the interaction potential between DNA-coated colloids with nanometer resolution and the macroscopic melting behavior. The range and strength of the interaction are measured and linked to key material design parameters, including DNA sequence, po…
The Integration Host Factor is a pH-responsive protein that switches from DNA bending to DNA bridging in acidic biofilm-like conditions
School of Physics and Astronomy, University of Edinburgh（爱丁堡大学物理与天文学院）；School of Biological Sciences, University of Edinburgh（爱丁堡大学生物科学学院）；School of Physics, Engineering & technology, University of York（约克大学物理、工程与技术学院）；Department of Biology, University of York（约克大学生物系）
Reliably distinguishing between cells based on minute differences in receptor density is crucial for cell-cell or virus-cell recognition, the initiation of signal transduction and selective targeting in directed drug delivery. Such sharp differentiation between different surfaces based on their receptor density can only be achieved by multivalent interactions. Several theoretical and experimental works have contributed to our understanding of this "superselectivity", however a versatile, controlled experimental model system that allows quantitative measurements on the ligand-receptor level is …
Nucleoid clustering drives stepwise expansion and segregation of replicating bacterial chromosomes
SUPA, School of Physics and Astronomy, University of Edinburgh（爱丁堡大学物理与天文学学院）；Dipartimento di Fisica e Astronomia and Sezione INFN, Universitá di Padova（帕多瓦大学物理与天文学系及INFN分部）
