3 research outputs found
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Assembly of Linked Nanocrystal Colloids by Reversible Covalent Bonds
The use of dynamically bonding molecules designed to reversibly link solvent-dispersed nanocrystals (NCs) is a promising strategy to form colloidal assemblies with controlled structure and macroscopic properties. In this work, tin-doped indium oxide NCs are functionalized with ligands that form reversible covalent bonds with linking molecules to drive assembly of NC gels. We monitor gelation using small angle X-ray scattering and characterize how changes in the gel structure affect infrared optical properties arising from the localized surface plasmon resonance of the NCs. The assembly is reversible because of the designed linking chemistry, and we disassemble the gels using two strategies: addition of excess NCs to change the ratio of linking molecules to NCs and addition of a capping molecule that displaces
the linking molecules. The assembly behavior is rationalized using a thermodynamic perturbation theory to compute the phase diagram of the NC–linking molecule mixture. Coarse-grained molecular dynamics simulations reveal the competition between loop and bridge linking motifs essential for understanding NC gelation. This combined experimental, computational, and theoretical work provides a platform for controlling and designing the properties of reversible colloidal assemblies that incorporate NC and solvent compositions beyond those compatible with other contemporary (e.g, DNA-based) linking strategies.We would like to acknowledge the UT Mass Spectrometry Facility for their
instrumental help and the UT NMR facilities for equipment use and assistance: NIH
Grant Number 1 S10 OD021508-01. This work was primarily supported by the
National Science Foundation through the Center for Dynamics and Control of
Materials: an NSF Materials Research Science and Engineering Center (NSF
MRSEC) under Cooperative Agreement DMR-1720595. This work was also
supported by NSF Graduate Research Fellowships DGE-1610403 (M.N.D. and
S.V.), an Arnold O. Beckman Postdoctoral Fellowship (Z.M.S.), NSF (CHE-
1905263), and the Welch Foundation (F-1848 and F-1696). E.V.A. acknowledges
support from the Welch Regents Chair (F-0046). We acknowledge the Texas
Advanced Computing Center (TACC) at The University of Texas at Austin for
providing HPC resources.Center for Dynamics and Control of Material
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TORC Bonding Pairs as an Alternative to Nucleobases in Self Replicating Polymers
The search for life on other planets is limited due to having only an incomplete knowledge of the origins of life on Earth as reference. While genetic information is stored and replicated by RNA and DNA using nucleobase chemistry here on Earth, this may not be the case on other planets with different environmental conditions. Tunable Orthogonal Reversible Covalent (TORC) bonds have promise in the creation of sequence-specific replicators because their orthogonality allows for the TORC bonding pairs to function similarly to nucleotide bases, defining and replicating the sequence, while their reversibility allows for duplexes to be separated for replication and their increased strength as covalent bonds would make these replicators more suitable to hot environments than the hydrogen bonding interactions observed in DNA replicators. This project represents the first step in the creation of sequence-specific TORC replicators by demonstrating the templating and synthesis of short peptide strands from a template strand using the hydrazone TORC bonding pair. In addition to this, macrocyclic products were also produced using these templates. This unexpected result holds promise for the creation of macrocyclic TORC replicators. The creation of macrocycles also has therapeutic applications, as macrocyclic peptides have useful properties but are generally difficult to synthesize, and the templates created in this project can quantitatively produce macrocyclic peptide products without any unwanted side products.Chemistr
Assembly of Linked Nanocrystal Colloids by Reversible Covalent Bonds
The use of dynamically bonding molecules designed to reversibly link solvent-dispersed nanocrystals (NCs) is a promising strategy to form colloidal assemblies with controlled structure and macroscopic properties. In this work, tin-doped indium oxide NCs are functionalized with ligands that form reversible covalent bonds with linking molecules to drive assembly of NC gels. We monitor gelation using small angle X-ray scattering and characterize how changes in the gel structure affect infrared optical properties arising from the localized surface plasmon resonance of the NCs. The assembly is reversible because of the designed linking chemistry, and we disassemble the gels using two strategies: addition of excess NCs to change the ratio of linking molecules to NCs and addition of a capping molecule that displacesthe linking molecules. The assembly behavior is rationalized using a thermodynamic perturbation theory to compute the phase diagram of the NC–linking molecule mixture. Coarse-grained molecular dynamics simulations reveal the competition between loop and bridge linking motifs essential for understanding NC gelation. This combined experimental, computational, and theoretical work provides a platform for controlling and designing the properties of reversible colloidal assemblies that incorporate NC and solvent compositions beyond those compatible with other contemporary (e.g, DNA-based) linking strategies.</div