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1. Self-Assembly of Stable Nanoscale Platelets from Designed Elastin-like Peptide–Collagen-like Peptide Bioconjugates

   https://doi.org/10.1021/acs.biomac.8b01681  

   Qin, Jingya ; Luo, Tianzhi ; Kiick, Kristi L. ( February 2019 , Biomacromolecules)
2. Microphase Separation of Resilin-like and Elastin-like Diblock Copolypeptides in Concentrated Solutions

   https://doi.org/10.1021/acs.biomac.1c00672  

   Navarro, Luis A. ; Ryan, Justin J. ; Dzuricky, Michael ; Gradzielski, Michael ; Chilkoti, Ashutosh ; Zauscher, Stefan ( September 2021 , Biomacromolecules)
3. Placement of tyrosine residues as a design element for tuning the phase transition of elastin-peptide-containing conjugates: experiments and simulations

   https://doi.org/10.1039/D0ME00051E  

   Taylor, Phillip A. ; Huang, Haofu ; Kiick, Kristi L. ; Jayaraman, Arthi ( January 2020 , Molecular Systems Design & Engineering)

   Elastin-like polypeptides (ELP) have been widely used in the biomaterials community due to their controllable, thermoresponsive properties and biocompatibility. Motivated by our previous work on the effect of tryptophan (W) substitutions on the LCST-like transitions of short ELPs, we studied a series of short ELPs containing tyrosine (Y) and/or phenylalanine (F) guest residues with only 5 or 6 pentapeptide repeat units. A combination of experiments and molecular dynamics (MD) simulations illustrated that the substitution of F with Y guest residues impacted the transition temperature ( T t ) of short ELPs when conjugated to collagen-like-peptides (CLP), with a reduction in the transition temperature observed only after substitution of at least two residues. Placement of the Y residues near the N-terminal end of the ELP, away from the tethering point to the CLP, resulted in a lower T t than that observed for peptides with the Y residues near the tethering point. Atomistic and coarse-grained MD simulations indicated an increase in intra- and inter-peptide hydrogen bonds in systems containing Y guest residues that are suggested to enhance the ability of the peptides to coacervate, with a concomitantly lower T t . Simulations also revealed that the placement of Y-containing pentads near the N-terminus ( i.e. , away from the CLP tethering point) versus C-terminus of the ELP led to more π–π stacking interactions at low temperatures, in agreement with our experimental observations of a lower T t . Overall, this study provides mechanistic insights into the driving forces for the LCST-like transitions of ELPs and offers additional means for tuning the T t of short ELPs for biomedical applications such as on-demand drug delivery and tissue engineering. 

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4. Cell Microencapsulation Within Engineered Hyaluronan Elastin‐Like Protein (HELP) Hydrogels

   https://doi.org/10.1002/cpz1.917  

   Hefferon, Meghan E. ; Huang, Michelle S. ; Liu, Yueming ; Navarro, Renato S. ; de Paiva Narciso, Narelli ; Zhang, Daiyao ; Aviles‐Rodriguez, Giselle ; Heilshorn, Sarah C. ( November 2023 , Current Protocols)

   Three‐dimensional cell encapsulation has rendered itself a staple in the tissue engineering field. Using recombinantly engineered, biopolymer‐based hydrogels to encapsulate cells is especially promising due to the enhanced control and tunability it affords. Here, we describe in detail the synthesis of our hyaluronan (i.e., hyaluronic acid) and elastin‐like protein (HELP) hydrogel system. In addition to validating the efficacy of our synthetic process, we also demonstrate the modularity of the HELP system. Finally, we show that cells can be encapsulated within HELP gels over a range of stiffnesses, exhibit strong viability, and respond to stiffness cues. © 2023 Wiley Periodicals LLC.

   Basic Protocol 1: Elastin‐like protein modification with hydrazine

   Basic Protocol 2: Nuclear magnetic resonance quantification of elastin‐like protein modification with hydrazine

   Basic Protocol 3: Hyaluronic acid–benzaldehyde synthesis

   Basic Protocol 4: Nuclear magnetic resonance quantification of hyaluronic acid–benzaldehyde

   Basic Protocol 5: 3D cell encapsulation in hyaluronan elastin‐like protein gels

    

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5. Electrochemical characterization of the stimuli-response of surface-immobilized elastin-like polymers

   https://doi.org/10.1039/C9SM01681C  

   Morales, Marissa A. ; Paiva, Wynter A. ; Marvin, Laura ; Balog, Eva Rose ; Halpern, Jeffrey Mark ( January 2019 , Soft Matter)

   Elastin-like polymers (ELPs) are frequently used in a variety of bioengineering applications because of their stimuli-responsive properties. Above their transition temperature, ELPs will adopt different structures that promote intra- and intermolecular hydrophobic contacts to minimize unfavorable interactions with an aqueous environment. We electrochemically characterize the stimuli-responsive behavior of surface-immobilized ELPs corresponding to two proposed states: extended and collapsed. In the extended state the ELPs are more solvated. In the collapsed state, triggered by introducing an environmental stimulus, non-polar intramolecular contacts within ELPs are favored, resulting in quantifiable morphological changes on the surface characterized using electrochemical impedance spectroscopy (EIS). Charge transfer resistance, a component of impedance, was shown to increase after exposing an ELP modified electrode to a high salt concentration environment (3.0 M NaCl). An increase in charge transfer resistance indicates an increase in the insulating layer on the electrode surface consistent with the proposed mechanism of collapse, as the ELPs have undergone morphological changes to hinder the kinetics of the redox couple exchange. Further characterization of the surface-immobilized ELPs showed a reproducible surface modification, as well as reversibility and tunability of the stimuli-response. 

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