Dr. Gang-yu Liu
University of California, Davis
Wednesday, October 07, 2020
Zoom Webinar @ 3:30 p.m.
Note: This page will be updated with a link to the webinar the day before the talk. The link will also be sent in a reminder email to chem-all on the day of the webinar.
While self-assembly is well known, controlling the assembly of molecules remains a major challenge in science and in chemistry. This seminar introduces our recent effort in developing new means to control assembly of molecules, bringing us closer to programmable synthesis for chemistry and materials science. Combining a microfluidic probe with atomic force microscopy (AFM), sub-femtoliter aqueous droplets containing designated solutes, e.g. polymers, produce well-defined features with dimensions as small as tens of nanometers. This presentation reports that the initial shape of the droplet and the concentration of solute within the droplets play a significant role in the final assembly of polymers due to the ultrafast evaporation rate and spatial confinement of the small droplets. These effects are used to control final molecular assembly in terms of feature geometry and distribution and packing of individual molecules within the features. Two applications will be discussed: 3-D nanoprinting and controlling the signaling processes and behavior of living cells.
Figure 1. [A] Schematic diagram illustrating the idea of microfluidic and AFM based delivery. Right: molecular assembly of polymers produced via controlling the delivery conditions, concentration (c), delivery pressure (p) and contact time (t): random and scattered distribution, 2-D closely packed structure and 3-D mound. [B] An AFM image of a DC after incubated on arrays of LPS nanostructures for 1 h. The inset in [B] is an AFM image of LPS nanostructures. Scale bar in all Figures, including the inset, is 5 µm.