MSGID: 1:317/3 63e32568   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Peptide 3D-printing inks could advance regenerative medicine    
    Lab opens new door to creating cell scaffolds for growing tissue,   
   studying disease    
      
     Date:   
         February 7, 2023   
     Source:   
         Rice University   
     Summary:   
         How do you build complex structures for housing cells using a   
         material as soft as jelly? Researchers have the answer with a new   
         3D-printing ink.   
      
      
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   FULL STORY   
   ==========================================================================   
   How do you build complex structures for housing cells using a material   
   as soft as jelly? Rice University scientists have the answer, and it   
   represents a potential leap forward for regenerative medicine and medical   
   research in general.   
      
      
   ==========================================================================   
   Researchers in the lab of Rice's Jeffrey Hartgerink have figured out   
   how to 3D- print the well-defined structures using a self-assembling   
   peptide ink.   
      
   "Eventually, the goal is to print structures with cells and grow mature   
   tissue in a petri dish. These tissues can then be transplanted to treat   
   injuries, or used to learn about how an illness works and to test drug   
   candidates," said Adam Farsheed, a Rice bioengineering graduate student   
   and lead author of the study, which appeared in Advanced Materials.   
      
   "There are 20 naturally occurring amino acids that make up proteins   
   in the human body," Farsheed said. "Amino acids can be linked together   
   into larger chains, like Lego blocks. When amino acid chains are longer   
   than 50 amino acids, they are called proteins, but when these chains are   
   shorter than 50 amino acids they are called peptides. In this work, we   
   used peptides as our base material in our 3D-printing inks."  Developed by   
   Hartgerink and collaborators, these "multidomain peptides" are designed   
   to be hydrophobic on one side and hydrophilic on the other. When placed   
   in water, "one of the molecules will flip itself on top of another,   
   creating what we call a hydrophobic sandwich," Farsheed said.   
      
   These sandwiches stack onto one another and form long fibers, which then   
   form a hydrogel, a water-based material with a gelatinous texture that   
   can be useful for a wide range of applications such as tissue engineering,   
   soft robotics and wastewater treatment.   
      
   Multidomain peptides have been used for nerve regeneration, cancer   
   treatment and wound healing, and have been shown to promote high levels   
   of cell infiltration and tissue development when implanted in living   
   organisms.   
      
   "We know that the multidomain peptides can safely be implanted in the   
   body," Farsheed said. "But what I was looking to do in this project was   
   to go in a different direction and show that these peptides are a great   
   3D-printing ink.   
      
   "It might be counterintuitive since our material is so soft, but I   
   recognized that our multidomain peptides are an ideal ink candidate   
   because of the way they self-assemble," he continued. "Our material can   
   reassemble after being deformed, similar to how toothpaste forms a nice   
   fiber when pushed out of a tube."  Farsheed's mechanical engineering   
   background allowed him to take an unconventional approach when testing   
   his hypothesis.   
      
   "I had more of a brute-force engineering approach where instead of   
   chemically modifying the material to make it more amenable to 3D printing,   
   I tested to see what would happen if I simply added more material,"   
   he said. "I increased the concentration about fourfold, and it worked   
   extremely well.   
      
   "There have been only a handful of attempts to 3D-print using other self-   
   assembling peptides, and that work is all great, but this is the first   
   time that any self-assembling peptide system has been used to successfully   
   3D-print such complex structures," Farsheed continued.   
      
   The structures were printed with either positively charged or negatively   
   charged multidomain peptides, and immature muscle cells placed on the   
   structures behaved differently depending on the charge. Cells remained   
   balled up on the substrate with a negative charge, while on the positively   
   charged material the cells spread out and began to mature.   
      
   "It shows that we can control cell behavior using both structural and   
   chemical complexity," Farsheed said.   
      
   Hartgerink is a professor of chemistry and bioengineering and associate   
   chair for undergraduate studies. Farsheed is a bioengineering graduate   
   student and lead author on the study. Additional study co-authors are   
   undergraduate student Adam Thomas and graduate student Brett Pogostin.   
      
   The National Institutes of Health (R01 DE021798) and the National Science   
   Foundation Graduate Research Fellowships Program supported the research.   
      
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   ==========================================================================   
   Story Source: Materials provided by Rice_University. Original written   
   by Silvia Cernea Clark.   
      
   Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Adam C. Farsheed, Adam J. Thomas, Brett H. Pogostin, Jeffrey D.   
      
         Hartgerink. 3D Printing of Self‐Assembling Nanofibrous   
         Multidomain Peptide Hydrogels. Advanced Materials, 2023; 2210378   
         DOI: 10.1002/ adma.202210378   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/02/230207191606.htm   
      
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