NU MRSEC Highlight SZLEIFER_OLVERA-1
Self-organization of grafted polyelectrolyte layers via the coupling of chemical equilibrium and physical interactions Mario Tagliazucchi, Mónica Olvera de la Cruz and Igal Szleifer (Published online March 4, 2010, doi: 10.1073/pnas.0913340107 (NSF MRSEC program DMR-0520513, NSF CBET-0828046, and Fulbright and CONICETFUDETEC Fellowships to MT))
Specific biological functions, such as signaling, synthesis of peptides and enzymatic activity, depend on the environment around the relevant active site. It is not clear how the enzymatic activity and conformation varies locally in cell environments since they are not homogeneous at the nanoscale. Researches at Northwestern University and the University of Buenos Aires in Argentina found that, in confined environments, molecules can regulate their charge and structure by adjusting their local environment via a delicate competition between physical interactions and chemical equilibrium, thereby generating heterogeneous distribution of charge and matter. They analyzed the changes in protonation state due to the self-assembly of hydrophobic end-tethered polyacids. The charged states and their self-assembly morphologies can be manipulated by changes in the solution pH and ionic strength. However, it was not understood how the chemical charge regulation couples with physical interactions to determine the morphology of these systems at the nanoscale. The researchers found ways to design systems that self-regulate their conformation into morphologies that can be manipulated in a reversible way. They have designed self-assembling domains that act as buffers within nanoscale domains; namely, finding a way to control the pH within these nano-containers that are different from those in the solution. This effort leads to ways of controlling morphology and function at the nanoscale by bulk solution changes, and it is probably the way that biological systems regulate chemical reactions for many of their functions. These results provide the guidelines to design intelligent sensors and microfluidic devices. Local pH inside micelles of end-‐grafted chains capable of controlling their charge as a function of bulk pH corrected to consider the potential inside the micelle.
Specific biological functions, such as signaling, synthesis of peptides and enzymatic activity, depend on the environment around the relevant active site. It is not clear how the enzymatic activity and conformation varies locally in cell environments since they are not homogeneous at the nanoscale. Researches at Northwestern University and the University of Buenos Aires in Argentina found that, in confined environments, molecules can regulate their charge and structure by adjusting their local environment via a delicate competition between physical interactions and chemical equilibrium, thereby generating heterogeneous distribution of charge and matter. They analyzed the changes in protonation state due to the self-assembly of hydrophobic end-tethered polyacids. The charged states and their self-assembly morphologies can be manipulated by changes in the solution pH and ionic strength. However, it was not understood how the chemical charge regulation couples with physical interactions to determine the morphology of these systems at the nanoscale. The researchers found ways to design systems that self-regulate their conformation into morphologies that can be manipulated in a reversible way. They have designed self-assembling domains that act as buffers within nanoscale domains; namely, finding a way to control the pH within these nano-containers that are different from those in the solution. This effort leads to ways of controlling morphology and function at the nanoscale by bulk solution changes, and it is probably the way that biological systems regulate chemical reactions for many of their functions. These results provide the guidelines to design intelligent sensors and microfluidic devices. Local pH inside micelles of end-‐grafted chains capable of controlling their charge as a function of bulk pH corrected to consider the potential inside the micelle.
