Experimental study of the conformation and dynamics of active colloidal polymers

活性胶体聚合物构象与动力学的实验研究

• 批准号: 2028652
• 负责人: Xiang Cheng
• 金额: $ 37.2万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-11-01 至 2024-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2028652&HistoricalAwards=false
• 关键词: Experimental; study; conformation; dynamics; active

An active fluid is a dispersion of self-driven particles in a liquid medium. This type of fluid is relevant to a broad class of biological and physical systems including suspensions of swimming microorganisms, synthetic colloidal swimmers and vibrated granular rods. Recent theories and simulations have greatly extended the study of simple active fluids made of compact solid particles to elongated flexible objects such as soft chains and filaments. Such research has transformed our understanding of the dynamics of flexible objects in nonequilibrium conditions (for example, biopolymers within living cells) and revealed unexpected collective dynamics of active fluids. Nevertheless, benchmark experiments that can quantitatively verify the wide range of theoretical and numerical predictions are still missing. This research project aims to address this gap and to perform experiments that study the shape and dynamics of active DNA-linked long chains of colloidal particles, the so-called colloidal polymers in analogy of linear polymer molecules. Two specific systems included in these studies are passive colloidal polymers immersed in light-powered bacterial suspensions and active Janus colloidal polymers whose activity arises internally from individual Janus particles via chemical reactions. The ultimate objective is to explore the possibility of using self-driven active colloidal polymers as artificial flagella. The project includes outreach efforts on designing demos for undergraduate fluid classes and for summer short courses attended by industrial practitioners. The project also aims to forge close collaborations between academic and industrial researchers.DNA-linked colloidal chains provide a concrete example of the classic bead-spring model of polymer molecules. By conveying activity to DNA-linked colloidal polymers, the research team will investigate the conformation and dynamics of active colloidal polymers and understand the fundamental polymer scaling relations out of equilibrium. The researchers will verify important theoretical and numerical predictions on the unusual behaviors of active polymers such as the swelling of polymer chains with activity, the self-assembly of hairpin structures, and the activity-induced softening and coil-to-globule transition. Moreover, by exploiting the collective dynamics of linked active Janus particles, the project participants will study a new approach for creating self-driven artificial flagella with periodic non-reciprocal beating motions. Such a flagellar structure would then be tested for driving the locomotion of synthetic microswimmers. Taken together, the project provides not only benchmark experiments corroborating existing theories and simulations but also a new way to engineer synthetic microswimmers for cargo delivery at microscopic scales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

活性流体是在液体培养基中的自动颗粒的分散。这种类型的液体与广泛的生物和物理系统有关，包括游泳微生物的悬浮液，合成胶体游泳者和振动的颗粒状棒。最近的理论和模拟大大扩展了对由紧凑型固体颗粒制成的简单活性流体的研究，以延长的柔性物体，例如软链和细丝。这样的研究改变了我们对非平衡条件下柔性物体动力学的理解（例如，活细胞内的生物聚合物），并揭示了活性流体的意外集体动力学。然而，可以定量验证广泛的理论和数值预测范围的基准实验仍然缺失。该研究项目旨在解决这一差距，并进行实验，以研究胶体颗粒的活性DNA连接长链的形状和动力学，胶体颗粒，即线性聚合物分子类似的所谓胶体聚合物。这些研究中包括的两个特定系统是浸入轻型细菌悬浮液和活跃的Janus胶体聚合物中的被动胶体聚合物，其活性通过化学反应内部来自单个Janus颗粒。最终目标是探索使用自动驱动的活性胶体聚合物作为人造鞭毛的可能性。该项目包括在设计本科液体课程的演示和工业从业人员参加的夏季短期课程方面的宣传工作。 该项目还旨在建立学术研究人员和工业研究人员之间的密切合作。与DNA相关的胶体链提供了一个经典的聚合物分子模型的具体示例。通过将活性输送到DNA连接的胶体聚合物中，研究小组将研究活跃的胶体聚合物的构象和动力学，并了解基本聚合物比例的基本缩放关系。研究人员将验证有关活性聚合物异常行为的重要理论和数值预测，例如聚合物链的肿胀随活性，发夹结构的自组装以及活性诱导的软化和线圈到全球体过渡。此外，通过利用链接的主动Janus粒子的集体动态，项目参与者将研究一种新的方法，用于创建具有周期性非近代击败动作的自我驱动的人造鞭毛。然后，将对这种鞭毛结构进行测试，以驱动合成微晶状体的运动。综上所述，该项目不仅提供了证实现有理论和仿真的基准实验，而且还提供了一种以微观尺度来设计合成微武器的新方法。该奖项反映了NSF的法定任务，并通过评估该基金会的智力功能和广泛的影响来评估NSF的法定任务。

项目成果

Crack patterns of drying dense bacterial suspensions

干燥致密细菌悬浮液的裂纹模式

• DOI: 10.1039/d2sm00012a
• 发表时间: 2022
• 期刊: Soft Matter
• 影响因子: 3.4
• 作者: Ma, Xiaolei;Liu, Zhengyang;Zeng, Wei;Lin, Tianyi;Tian, Xin;Cheng, Xiang
• 通讯作者: Cheng, Xiang

The colloidal nature of complex fluids enhances bacterial motility

• DOI: 10.1038/s41586-022-04509-3
• 发表时间: 2022-03-31
• 期刊: NATURE
• 影响因子: 64.8
• 作者: Kamdar, Shashank;Shin, Seunghwan;Cheng, Xiang
• 通讯作者: Cheng, Xiang

To cross or not to cross: Collective swimming of Escherichia coli under two-dimensional confinement

• DOI: 10.1103/physrevresearch.4.023105
• 发表时间: 2022-05-09
• 期刊: PHYSICAL REVIEW RESEARCH
• 影响因子: 4.2
• 作者: Ghosh, Dipanjan;Cheng, Xiang
• 通讯作者: Cheng, Xiang

Density fluctuations and energy spectra of 3D bacterial suspensions

3D 细菌悬浮液的密度波动和能谱

• DOI: 10.1039/d1sm01183a
• 发表时间: 2021
• 期刊: Soft Matter
• 影响因子: 3.4
• 作者: Liu, Zhengyang;Zeng, Wei;Ma, Xiaolei;Cheng, Xiang
• 通讯作者: Cheng, Xiang