Welcome to the Schwartz Research Group!

The Schwartz Research Group at CU-Boulder is broadly interested in interfacial science. We are leading the way in the development of liquid crystal sensors, chemically-modified catalysts, and single-molecule imaging methods. 

General Interests

  • Dynamics of (bio)molecules at interfaces
  • Molecular targeting (biosensing)
  • Liquid crystal anchoring and alignment
  • (Catalytic) surface modification

Instruments and Methods

  • Single-molecule total internal reflection fluorescence microscopy (TIRFM)
  • Polarized light microscopy
  • Surface modification (thin films and self-assembled monolayers)
  • Surface characterization (contact angle goniometry, FTIR, ellipsometry)
  • Atomic force microscopy
  • Spectroscopy (circular dichroism, UV-vis, fluorescence)
  • Numerical simulations and machine-learning
  • Langmuir trough
  • Brewster angle microscopy

Research Highlights

Advanced Functional Materials: Visualizing Liposome Fusion
Using Liquid Crystals

DOI: 10.1002/adfm.201303885 Understanding how to control liposome fusion has significant value toward understanding biological systems and advancing technologies such as drug delivery strategies, synthetic gene transfer agents, and bio-sensing applications. In collaboration with the Goodwin Research Group we have developed an approach for monitoring receptor-mediated fusion that exploits the advantageous properties of liquid crystals (e.g. optical anisotropy, long range orientational order, and sensitivity to external stimuli). Oligonucleotides were anchored within the bilayer of dispersed liposomes and at a PEG-lipid laden aqueous/LC interface. When these oligonucleotides were complementary, DNA hybridization occurred, promoting lipid mixing with the LC interface and depositing lipids to the interface at a high enough density to initiate LC re-orientation to a homeotropic state. The applicability of this approach as a bio-sensing strategy was demonstrated by incorporating aptamer–ligand binding into the detection scheme to modulate fusogenic activity. Future work in this area will involve optimizing conditions for advanced bio-sensing (e.g. detection in complex media, improved sensitivity) and exploiting this system to study naturally occurring biological receptors (e.g. SNAREs).

JACS Spotlight: Surface-Bound Polymers Wriggle and Hop

DOI: 10.1021/ja407396v It is well known that polymers interact with surfaces, but the mystery lies in how exactly they move once attached. Polymers have been commonly assumed to move about the two- dimensional plane of the surface to which they are adsorbed, but a new study suggests their behavior is much more dynamic. Michael Skaug, Joshua Mabry, and Daniel Schwartz use single-molecule tracking experiments to reveal that the widely used polymer, poly- (ethylene glycol) (PEG), wriggles and hops along hydrophobic surfaces. The team uses total internal reflection fluorescence microscopy to observe the movements of individual surface-adsorbed PEG molecules and find mobility is dependent on molecular weight. The results suggest that the interactions between surfaces and molecules in bulk solution may be stronger than previously believed, which could help explain certain previously puzzling phenomena, such as anomalously slow removal of surface-adsorbed polymers and the influence of highly attractive surfaces on the diffusion of polymers in solution. But it remains an open question whether this desorption-mediated mechanism observed for PEG can be assumed for other classes of polymers.

Reprinted (adapted) with permission from Spotlights on Recent JACS Publications. Christine Herman. Journal of the American Chemical Society 2013 135 (49), 18237-18237. Copyright (2013) American Chemical Society.