by Serena Blacklow
Here at Harvard’s own Wyss Institute for Biologically Inspired Engineering, researchers have introduced a new method of self-assembly using DNA glue. Self-assembly, the ability of objects to spontaneously come together, enables scientists and engineers to attach objects too small to be manipulated by hand. Although there has been much progress with self-assembly on a nano-scale level, self-assembly on the meso-scale (30 microns to 1 millimeter in diameter) level had been elusive until now (1). In this new method of self-assembly, “giant” DNA strands, made up of repeats of a shorter DNA sequence, coat a hydrogel (water-filled gel) “brick.” The attraction between complementary DNA strands holds their associated bricks together, enabling the bricks to assemble with each other (2). Since DNA is “programmable,” it can be engineered into a variety of sequences. By coating bricks with unique combinations of these sequences, scientists can create diverse structures with high binding specificity. Use of small, DNA-coated connector cubes to hold together multiple hydrogels enables further complexity (3).
The ability for self-assembly of these medium-sized hydrogels has great therapeutic potential. As biocompatible and biodegradable substances, hydrogels, unlike many pharmaceutical or surgical treatments, pose few health risks. Scientists envision injecting cell-carrying hydrogels into the body, where they would self-assemble and degrade to leave patients with new cells (3). In addition to enabling easier tissue or organ reconstruction, such innovations could eliminate the need for some surgeries.
1. S. Sonaliy, “Wyss Researchers Use DNA as Smart Glue,” The Harvard Crimson, 2013.
2. M. G. Hao Qi, Yanan Du, Casey Grun, Hojae Bae, Peng Yin & Ali Khademhosseini, DNA-directed self-assembly of shape-controlled hydrogels. Nature Communications, (September 9, 2013, 2013).
3. D. Ferber, “DNA glue directs tiny gel ‘bricks’ to self-assemble: New method could help reconnect injured organs or build functional human tissues,” Harvard Gazette, September 9, 2013.
4. D. Ferber, “Programmable glue made of DNA directs tiny gel bricks to self-assemble,” September 9, 2013.