(2w) Nanoengineering of Colloidal Soft Matter Towards Optical and Biological Applications

My Ph.D. research with Prof. Peidong Yang at the University of California, Berkeley, focused on developing inorganic nanowires with tailored properties for optoelectronic applications. I led a collaborative effort with BASF, and realized low-haze, high-stability metal nanowires for transformative innovations in the field of transparent conductors. Another major accomplishment of my thesis is the development of copper nanomaterials for CO₂ electrochemical reduction. We achieved highly efficient and selective CH₄ production by understanding and optimizing copper nanowires' surface structure and twin domains. I also developed low-temperature, fully solution-based syntheses of III-V and Si alloy nanowires for photoelectrochemistry (PEC) applications.

My postdoctoral research with Prof. David Pine at New York University lies mainly in the field of soft matter where I am particularly interested in studying the nanoscale interactions and dynamics between DNA-coated colloids during colloidal self-assembly. I designed and built a customized total internal reflection microscope (TIRM) that achieves in situ, direct measurement of single-colloid dynamics with nanometer-scale resolution. Combined with first-principal modeling, our results can quantitively disentangle the complex interactions between DNA-coated colloids that include hybridization, polymer brush steric repulsion, electrostatic repulsion, van der Waals, and depletion interaction. Furthermore, through Brownian Dynamic simulations, we identified the critical role of photon counting statistics in potential energy measurements. We are currently working on instrumentational developments to further increase spatial resolution.

Research Interests

Colloidal soft materials such as colloids, polymers, and liquids are important materials systems in both technological applications and biological processes. Many successful applications hinge on the nanoscale engineering of the material units, e.g., to modulate the interfacial interactions to achieve microscale organization/assembly or introduce chemical functionalities that interact or mimic biological systems. Recently, there have been encouraging developments in preparing high-quality colloidal particles with various surface modifications such as DNA, lipids, and selective patch. However, the precise structural control of synthetic colloids remains a challenge. Moreover, in many soft matter systems involving synthetic colloids or biological cells, while the material units are in micrometer scales, particle interactions are in the nanometer range, which is challenging even to understand, let alone control.

I aim to leverage my past research experience in soft matter physics, nanotechnology, and materials chemistry to develop nanoengineered, functional soft materials for optical and biological applications. In specific, there are three research themes that I intend to pursue. (1) Engineering DNA-mediated hybrid assembly between colloids and optically active nanoparticles towards fully solution-based 3D photonic crystals for sensing and lasering. (2) Developing bottom-up soft metamaterials by synthesizing polymer/nanoparticle complex units that have controlled shape, size, and valance, for cloaking, super-lensing and, light-harvesting applications. (3) Developing cell-mimicking liquid colloids with mobile ligand/receptor surface modification for studying cell/virus dynamics and interactions, using advanced 3D total internal reflection microscopy with nanometer resolution and environmental control capability.

Teaching Interests

One of the major reasons that draws me into an academic career is teaching. I have acquired extensive teaching experience by serving as a teaching assistant for many undergraduate courses with excellent evaluation. For the past ten years, I served as a teaching assistant in several undergraduate courses, including Organic Chemistry, Physical Chemistry, General Chemistry, and Inorganic Chemistry, where I taught full lab classes, led discussion sessions, held office hours, and helped design course materials/homework. The goal of my teaching is to guide my students to obtain and retain knowledge, establish critical thinking and problem‐solving ability, and finally provide methods and skill foundation that allows students to extend what they learned. Moreover, I have had the privilege to mentor several undergraduate and graduate students for research. I found great success as well as satisfaction in mentoring aspiring junior scholars. Two undergraduate students I mentored delivered exceptional research work at UC Berkeley and continued to pursue Ph.D. at Cal Tech.

My academic experiences touch a wide background of disciplines, including chemistry, material sciences, polymer science, and soft matter physics, making me qualified to teach a broad range of topics at undergraduate and graduate levels. I am interested in teaching a wide range of Chemical Engineering undergraduate courses, including but not limited to Principles of Chemical Enigneering, Thermodynamics, and Polymers Science and Engineering. Graduate-level teaching interests include Surface Chemistry, Chemical Kinetics and Catalysis, Renewable Energy, Interfacial Phenomena, and Electrochemical Energy Conversion and Storage. In addition, I am interested in developing interdisciplinary courses for senior undergraduate and graduate students based on my current/future research work.

Select Publications (^* indicates equal contribution): 9 first-authored journal articles (13 in total), 4 patents, >1700 citations.

[1] Cui, F.^*,Marbach, S.^*, Zheng, J., M. Holmes-Cerfon, M. & Pine, D. Comprehensive view of nanoscale interactions between DNA-coated colloids. Nat. Commun. 13, 2304, (2022). (Featured in Nature Communications Editors’ Highlights)

[2] Cui, F. & Pine, D. Effect of photon counting shot noise on total internal reflection microscope. Soft Matter 18, 162 (2022).

[3] Niu, Z.^*,Cui, F.^*, Kuttner, E., Xie, C., Chen, H., Sun, Y., Dehestani, A., Schierle-Arndt, k. & Yang, P. Synthesis of silver nanowires with reduced diameters using benzoin-derived radicals to make transparent conductors with high transparency and low haze. Nano Lett. 18, 5329 (2018).

[4] Niu, Z.^*,Cui, F.^*, Yu, Y., Becknell, N., Sun, Y., Khanarian, G., Kim, D., Dou, L., Dehestani, A., Schierle-Arndt, K., & Yang, P. Ultrathin epitaxial Cu@Au core-shell nanowires for stable transparent conductors. J. Am. Chem. Soc. 139, 7348 (2017).

[5] Cui, F., Dou, L., Yang, Q., Yu, Y., Niu, Z., Sun, Y., Liu, H., Dehestani, A., Schierle-Arndt, K., & Yang, P. Benzoin radicals as reducing agent for synthesizing ultrathin copper nanowires. J. Am. Chem. Soc. 139, 3027 (2017).

[6] Li, Y.^*, Cui, F.^*, Ross, M., Kim, D., Sun, Y., & Yang, P. Structure-sensitive CO₂ electroreduction to hydrocarbons on ultrathin five-fold twinned copper nanowires. Nano Lett. 17, 1312 (2017).

[7] Dou, L.^*, Cui, F.^*, Yu, Y., Khanarian, G., Eaton, S., Yang, Q., Resasco, J., Schildknecht, C.,
Schierle, K. & Yang, P. Solution processed copper reduced-graphene-oxide core-shell nanowire transparent conductors. ACS Nano 10, 2600 (2016).

[8] Sun, J.^*, Cui, F.^*, Kisielowski, C., Yu, Y., Kornienko, N. & Yang, P. Low-temperature solution-phase growth of silicon and new silicon-containing alloy nanowires. J. Phys. Chem. 120, 20525 (2016).

[9] Cui, F., Yu, Y., Dou, L., Sun, Yang, Q., Schildknecht, C., Schierle-Arndt, K. & Yang, P. Synthesis of ultrathin copper nanowires using tris(trimethylsilyl)silane for highperformance and low-haze transparent conductors. Nano Lett. 15, 7610 (2015).