Corporate Banner
Satellite Banner
Scientific Community
Become a Member | Sign in
Home>News>This Article

Programmable Glue Made of DNA Directs Tiny Gel Bricks to Self-Assemble

Published: Thursday, September 12, 2013
Last Updated: Thursday, September 12, 2013
Bookmark and Share
New method could help to reconnect injured organs or build functional human tissues from the ground up.

A team of researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University has found a way to self-assemble complex structures out of bricks smaller than a grain of salt. The self-assembly method could help solve one of the major challenges in tissue engineering: regrowing human tissue by injecting tiny components into the body that then self-assemble into larger, intricately structured, biocompatible scaffolds at an injury site.

The key to self-assembly was developing the world's first programmable glue. The glue is made of DNA, and it directs specific bricks of a water-filled gel to stick only to each other, the scientists report in the September 9th online issue of Nature Communications.

"By using DNA glue to guide gel bricks to self-assemble, we're creating sophisticated programmable architecture," says Peng Yin, Ph.D., a Core Faculty member at the Wyss Institute and senior coauthor of the study, who is also an Assistant Professor of Systems Biology at Harvard Medical School. This novel self-assembly method worked for gel bricks from as small as a speck of silt (30 microns diameter) to as large as a grain of sand (1 millimeter diameter), underscoring the method's versatility.

The programmable DNA glue could also be used with other materials to create a variety of small, self-assembling devices, including lenses, reconfigurable microchips, and surgical glue that could knit together only the desired tissues, said Ali Khademhosseini, Ph.D., an Associate Faculty member at the Wyss Institute who is the other senior coauthor of the study.

"It could work for anything where you'd want a programmable glue to induce assembly of higher-order structures, with great control over their final architecture -- and that's very exciting," said Khademhosseini, who is also an Associate Professor at Harvard-MIT's Division of Health Sciences and Technology (HST), Brigham and Women's Hospital, and Harvard Medical School.

To fabricate devices or their component parts, manufacturers often start with a single piece of material, then modify it until it has the desired properties. In other cases, they employ the same strategy as auto manufacturers, making components with the desired properties, then assembling them to produce the final device. Living organisms fabricate their tissues using a similar strategy, in which different types of cells assemble into functional building blocks that generate the appropriate tissue function. In the liver, for example, the functional building blocks are small tissue units called lobules. In muscle tissue, the functional building blocks are muscle fibers.

Scientists have tried to mimic this manufacturing strategy by developing self-assembling systems to fabricate devices. For example, last year Yin and his team reported in Science that they had developed miniscule "DNA bricks" smaller than the tiniest virus that self-assemble into complex nanoscale 3D structures.

Now, he and Khademhosseini sought to create a similar programmable, self-assembling system for mesoscale components -- those with edge widths ranging from 30 microns to 1000 microns (1 millimeter). They focused first on creating a system in which bricks of biocompatible, biodegradable gels called hydrogels self-assemble into complex structures. For future applications, small hydrogel bricks containing human cells could potentially be injected into the body. The bricks would assemble, then the cells would knit together to form functional tissue as the hydrogels break down.

In previous attempts to self-assemble hydrogel bricks into complex structures, scientists faced a challenge: the bricks often glom onto one another rather than assembling into the desired architecture. Yin and Khademhosseini needed a way to help each component stick only to specific partners, but not to other components. In other words, they needed programmable glue.

DNA was ideal for the task. It stores genetic information as a sequence of four chemical "letters," or nucleotides, that bind in a specific way to complementary nucleotides (A to T, and C to G). A single strand of DNA adheres tightly to a second strand, but only if the second strand has a sequence of nucleotides that is complementary to the first. And even a short piece of DNA can have a huge number of possible sequences, which makes the glue programmable.

The researchers used enzymes to multiply a snippet of DNA into long pieces of DNA called "giant DNA" that contained multiple copies of that snippet. When they coated hydrogel cubes with giant DNA, the cubes adhered only to partner cubes coated with matching giant DNA. Since scientists can synthesize snippets of DNA with any sequence they want, this meant that giant DNA functioned as programmable DNA glue.

To assemble hydrogel cubes into larger structures, they used smaller hydrogel cubes as connectors. They coated the connector cube with their DNA glue, then attached it to one of the six faces of a larger cube. A large cube outfitted this way adhered only to other large cubes whose connectors had matching DNA glue.

By placing connector cubes on various faces of the larger cubes, they programmed the larger cubes to self-assemble into specific shapes, including a matching pair of cubes, a linear chain, a square, and a T-shaped structure.

The method was so specific that when the researchers placed 25 pairs of matched cubes in a single pot, all the cubes located and adhered only to their partners. This ability to assemble multiple components simultaneously is called multiplexity, and the new system has the highest degree of multiplexity of all existing mesoscale self-assembly systems.

"Designing a strategy that leverages the power of self assembly used by living systems to direct construction of tissues from tiny component parts represents an entirely new approach for tissue engineering," said Don Ingber, M.D., Ph.D., the Wyss Institute's Founding Director. "Peng and Ali have created an elegant and straightforward method that could permit tissues to be reconstructed from within after a simple injection, rather than requiring major surgery."

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,800+ scientific posters on ePosters
  • More than 4,000+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Scientific News
New Tech Vastly Improves CRISPR/Cas9 Accuracy
A new CRISPR/Cas9 technology developed by scientists at UMass Medical School is precise enough to surgically edit DNA at nearly any genomic location, while avoiding potentially harmful off-target changes typically seen in standard CRISPR gene editing techniques.
New Class of RNA Tumor Suppressors Identified
Two short, “housekeeping” RNA molecules block cancer growth by binding to an important cancer-associated protein called KRAS. More than a quarter of all human cancers are missing these RNAs.
Biologists Induce Flatworms to Grow Heads and Brains of Other Species
Findings shed light on role of a new kind of epigenetic signaling in evolution, could yield clues for understanding birth defects and regeneration.
Turning up the Tap on Microbes Leads to Better Protein Patenting
Mining millions of proteins could become faster and easier with a new technique that may also transform the enzyme-catalyst industry, according to University of California, Davis, researchers.
Mathematical Model Forecasts the Path of Breast Cancer
Chances of survival depend on which organs breast cancer tumors colonize first.
Exploring the Causes of Cancer
Queen's research to understand the regulation of a cell surface protein involved in cancer.
Ancient Viral Molecules Essential for Human Development
Genetic material from ancient viral infections is critical to human development, according to researchers at the Stanford University School of Medicine.
Tardigrade's Are DNA Master Thieves
Tardigrades, nearly microscopic animals that can survive the harshest of environments, including outer space, hold the record for the animal that has the most foreign DNA.
The Secret Behind the Power of Bacterial Sex
Migration between different communities of bacteria is the key to the type of gene transfer that can lead to the spread of traits such as antibiotic resistance, according to researchers at Oxford University.
Farming’s in Their DNA
Ancient genomes reveal natural selection in action.
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,800+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,000+ scientific videos