Protein Corona and Secondary Structure in Response to Nanoparticle Pegylation

Abstract

Organisms, from algae to humans are known to mold complex, hierarchical hard tissues from minerals using biomolecular templates and additives. Molecular-level mechanistic understanding of how these biomolecules, particularly proteins, participate in the nucleation and growth of these inorganic crystals has been a longstanding goal. We design peptides with transformative abilities over calcite crystals using Rosetta. Based on the theory of how additives alter crystal nucleation and growth, we employ four modification strategies to modify the morphology of the crystal, viz. a peptide binding to a face, an array of peptides binding to a face, peptides pinning steps and peptides blocking kinks. To test the designs, we employ a variety of techniques ranging from measurements at the atomic scale to full crystal observations. We also investigate alternative mechanisms of modification by comparing the interactions predicted by Rosetta in other select states to those in the target state. For each design, we obtain the solution-state structure of the peptide by circular dichroism. To test peptides designed against a non-native face of calcite, we artificially stabilize the face for binding measurements. The overall crystal morphology change is then tested by incubating supersaturated precursor solutions with the design peptides. To confirm the predicted mechanism of growth alternation, we observe the change in kinetics of calcite step growth with peptide doping using in situ AFM, and report calcite step velocities. Finally, by nucleating calcite on a monolayer of the designed peptides, we examine the face on which calcite nucleated and compare it to our target face. These experimental results provide a feedback loop to the next generation of designs and enable the rational design of bio-surface interactions. 3191-Pos Board B621Examining Bacterial Cell Interactions using Atomic Force Microscopy Ronald Aucapina, Nadia Ouedraogo, Megan A. Ferguson. SUNY New Paltz, New Paltz, NY, USA. Given the prevalence of bacterial biofilms in both native and engineered environments, our understanding of their interactions with both other bacteria and abiotic surfaces is quite limited. In this research we use an AFM to analyze the interactions of bacteria such as E. coli and a saprophytic, biofilm forming variant of B. bacteriovorus with other bacteria and chemically characterized surfaces. Tipless AFM cantilevers were left unmodified (Si3N4), or coated with a monolayer of E. coli. These cantilevers were then used to collect force curves on biofilms of B. bacteriovorus and E.coli as well as chemically characterized surfaces such as mica, silicon, and poly-L-lysine-coated glass. The greater the cantilever's contact time with the surface, the more force and energy was required to retract from the surface. E. coli-coated cantilevers had more adhesion to B. bacteriovorus biofilms than to E. coli biofilms, but even E. coli -B. bacteriovorus interaction paled in comparison to adhesion between E. coli biofilms and abiotic surfaces. Further results...