| Janus particles have two distinct surfaces that provide an asymmetry that can impart vastly different chemical or physical properties and directionality within one particle. However, there is little known about how amphiphilic Janus particles will interact with lipid membranes. Here, we investigate the interaction of giant unilamellar vesicles (GUVs) with self-assembling Janus particles. Previous studies in the Yu lab discovered Janus particles densely concentrate on the inner leaflet of the GUVs due to weak particle-lipid interactions. Of particular interest was determining the particles' rotational dynamics while interacting with lipid membranes. Results showed that Janus particles display heterogeneous rotational dynamics and little translational movement when interacting with GUVs.;We are interested in developing a better understanding of the growth of bacterial cell walls, which are primarily composed of peptidoglycan (PG). PG is responsible for the cell size, shape, and mechanical strength and, therefore, is a possible target for antibiotic intervention. Fluorescently labeled D-amino acids (FDAAs) incorporate directly into the PG during synthesis and permit real time observation of cell wall growth. We have developed an automated microfluidic device with an integrated nanochannel array to trap cells and simplify the PG labeling process. Our poly(dimethlysiloxane) (PDMS)-based device consists of over 1200 nanochannels and has on-chip pneumatic pumps and valves to control reagent delivery to the trapped cells. First, we determined there was no effect on the growth and division properties of Bacillus subtilis in our automated microfluidic device or from FDAA labeling. Next, we demonstrated efficient labeling of new growth in the cell walls, decreased labeling times, and elimination of the labor-intensive, multistep process necessary to label and wash cells prior to imaging. In addition, our device permits high-resolution time-lapse imaging and analysis for observing cell wall synthesis. |
