TITLE: Determining Suitable Conditions for DNA Ligands with Reversible Binding Activity to Antimicrobial Peptides
PI: Valeria Tohver Milam (MSE) Co-PI: Johnna S. Temenoff (BME)
Materials with programmable antimicrobial capabilities hold promise for effective localized delivery of antimicrobial agents at relatively lower doses compared to systemic delivery of antibiotics. The longer term research goal is to identify high affinity ligands that can programmatically bind to, and then release bioactive antimicrobial peptides (AMPs) from material matrices. These ligands, known as aptamers, are single-stranded oligonucleotides that bind with high affinity and specificity to a particular non-nucleotide target, but theoretically retain binding capabilities to complementary oligonucleotide targets. We hypothesize that we can screen for DNA aptamers that retain serial binding capabilities to bind first to AMP targets (to temporarily immobilize antimicrobial agents to the material surface) and then to complementary oligonucleotide sequences (to drive release of active antimicrobial agents from the material surface). To undertake this longer term goal in a future full proposal, the experimental objectives of this seed grant proposal focus on successfully generating key preliminary data to help optimize the screening conditions (to identify aptamers from random sequence libraries) in order to (i) successfully immobilize AMP targets to material substrates (ii) minimize undesired nonspecific attractions between the AMP targets and their material substrate. While the proposed experimental system focuses on natural antimicrobial agents, if successful, the proposed approach provides a promising and efficient route to identifying aptamers that can act as both capture and programmable release agents for a variety of molecular (e.g. fluorescent dyes) and macromolecular (e.g. therapeutic proteins) agents incorporated on material surfaces or in the bulk material.
TITLE: Biofilm-Stabilized Cylindrical and Toroidal Air Bubbles: Materials Science & Engineering Applications
PI: Paul S. Russo (MSE, Chemistry & Biochemistry) Co-PI: Jerry Qi, (ME)
Hydrophobins are small amphipathic proteins: one side shuns water, the other seeks it. Unlike common amphipathic molecules (e.g., sodium dodecyl sulfate used in soap) hydrophobins are nearly rigid, thanks to an elaborate disulfide crosslinking network that stabilizes their compact, globular structure. Hydrophobins have been called nature’s Janus particles, and nature makes them by the ton in mushrooms and other forms of fungi. A particular hydrophobin in our possession, cerato ulmin or CU, stabilizes cylindrical microbubbles upon simple agitation of its dilute suspensions. Within the last year, graduate student Xujun Zhang discovered that application of pressure in a prescribed sequence converts these cylindrical bubbles to air-filled toroids. No other system reproducibly produces stable “air donuts” of sub-millimeter size. This proposal will combine physicochemical expertise (Russo) with mechanical testing and characterization (Qi) to develop applications for both cylindrical and toroidal bubbles. For an intense 3-month period, data will be generated to support proposals targeting lightweight, high-surface-area, and directed strength materials.