Cells typically make their exterior barrier (known as the membrane) out of lipids. To replicate a similar functionality for ProteoCell, the Sullivan lab will create a membrane out of peptides (i.e.small synthetic proteins made of select repeating amino acid sequences). A key focus area in the Sullivan lab is the development of protein and peptide biomaterials whose structure and behavior change in response to stimulus application (e.g., temperature, light, enzyme exposure). By applying a stimulus, a peptide’s structure changes providing selective assembly/disassembly. Stimuli-responsive biomaterials are ideal for applications ranging from drug delivery to synthetic cells to biotechnology applications. In the context of the ProteoCel project, we are employing temperature-responsive peptide materials in new ways such that these peptides self-assemble to create a membrane around the ProteoCell cytoplasm. Here, we will be using conjugates of elastin-like and collagen-like peptides to achieve the desired temperature-responsiveness. The temperature-response will be tuned by modifying the amino acid sequence in their structure. In addition to responsive structural roles, the peptide-based membrane will work to scaffold functional proteins and provide additional control to molecule transfer into/out of ProteoCells.