The Qian Lab

California Institute of Technology

The World's Smallest Tic-Tac-Toe Game Board with DNA


Caltech News (December 19, 2018) — It was just about a year ago that Caltech scientists announced they had used a technique known as DNA origami to create tiles that could be designed to self-assemble into larger nanostructures that carry predesigned patterns. They chose to make the world's smallest version of the iconic Mona Lisa. The feat was impressive, but the technique had a limitation similar to that of Leonardo da Vinci's oil paints: Once the image was created, it could not easily be changed. Now, the Caltech team has made another leap forward with the technology. They have created new tiles that are more dynamic, allowing the researchers to reshape already-built DNA structures. More…

Daily Mail: Tiny tic-tac-toe: Researchers reveal microscopic board made using DNA
India Today: After Mona Lisa, researchers made world's smallest tic-tac-toe game board with DNA
Digital Trends: Caltech scientists used DNA to play the world’s tiniest game of tic-tac-toe
GEN: Tic-tac-DNA displaces Mona Lisa
Ars Technica: Caltech scientists use DNA tiles to play tic-tac-toe at the nanoscale
Smithsonian: World’s tiniest tic-tac-toe game is made of DNA tiles
NIH Director's Blog: World’s smallest tic-tac-toe game built from DNA

Test Tube Artificial Neural Network Recognizes "Molecular Handwriting"


Caltech News (July 5, 2018) — Researchers at Caltech have developed an artificial neural network made out of DNA that can solve a classic machine learning problem: correctly identifying handwritten numbers. The work is a significant step in demonstrating the capacity to program artificial intelligence into synthetic biomolecular circuits. More…

Nature Podcast: Identifying numbers with DNA
The Register: Boffins build neural networks fashioned out of DNA molecules
IEEE Spectrum: How to make an artificial neural net with DNA
Daily Mail: Scientists have created an AI inside a test tube using strands of DNA
Financial Express: Artificial intelligence network made of DNA can identify 'molecular handwriting'
Motherboard: Scientists invented AI made from DNA
GEN: Artificial bimolecular networks open door to sophisticated diagnostic testing

The World's Smallest Mona Lisa


Caltech News (December 6, 2017) — DNA origami revolutionized the field of nanotechnology, opening up possibilities of building tiny molecular devices or "smart" programmable materials. However, some of these applications require much larger DNA origami structures. Now, scientists at Caltech have developed an inexpensive method by which DNA origami self-assembles into large arrays with entirely customizable patterns, creating a sort of canvas that can display any image. To demonstrate this, the team created the world's smallest recreation of Leonardo da Vinci's Mona Lisa—out of DNA. More…

Newsweek: DNA folds itself like origami to re-create Mona Lisa
Daily Mail: Leonardo da Vinci's masterpiece is recreated using DNA
Engadget: The world's smallest Mona Lisa is made from DNA
Chemistry World: DNA origami makes it big
The Scientist: The biggest DNA origami structures yet
GEN: DNA origami creates the world's smallest Mona Lisa
Chemical & Engineering News: DNA origami hits the big time

Sorting Molecules with DNA Robots


Caltech News (Septebmer 14, 2017) — Imagine a robot that could help you tidy your home: roving about, sorting stray socks into the laundry and dirty dishes into the dishwasher. While such a practical helper may still be the stuff of science fiction, Caltech scientists have developed an autonomous molecular machine that can perform similar tasks—at the nanoscale. This "robot," made of a single strand of DNA, can autonomously "walk" around a surface, pick up certain molecules and drop them off in designated locations. More…

LA Times: Caltech scientists make robots out of DNA that can pick stuff up and move it around
ABC News: Scientists build 'DNA robots' that transport molecular cargo using 'arms' and 'feet'
The Scientist: Cargo-sorting DNA robots
IEEE Spectrum: DNA robots can deliver molecular packages
Chemical & Engineering News: DNA robot sorts and delivers
GEN: DNA robots built for random walks, deliberate sorts
Chemistry World: Walking DNA robot sorts out molecular mess

Warning: Some other media misinterpreted the work and confused prospects with facts. These DNA robots work neither in the blood nor in the body. They work in test tubes, the cleanest environment for discovering engineering principles.

First artificial neural network created out of DNA:
molecular soup exhibits brainlike behavior


Caltech News (July 20, 2011) — Artificial intelligence has been the inspiration for countless books and movies, as well as the aspiration of countless scientists and engineers. Researchers at the California Institute of Technology (Caltech) have now taken a major step toward creating artificial intelligence -- not in a robot or a silicon chip, but in a test tube. The researchers are the first to have made an artificial neural network out of DNA, creating a circuit of interacting molecules that can recall memories based on incomplete patterns, just as a brain can. More…

msnbc News: Test-tube brain aces 'plop' quiz — could lead to drugs that think
The Hindu: Scientists step closer to creating test tube intelligence
Discovery News: Test tube DNA brain gets quiz questions right
CNET News: Researchers build DNA neural network that thinks
Science 2.0: Artificial neural network, made out Of DNA
IBTimes: Caltech scientists create "tiny brain" neural network using DNA strands
Ars Technica: DNA circuits used to make neural network, store memories

Researchers build largest biochemical circuit
out of small synthetic DNA molecules


Caltech News (June 2, 2011) — In many ways, life is like a computer. An organism's genome is the software that tells the cellular and molecular machinery -- the hardware -- what to do. But instead of electronic circuitry, life relies on biochemical circuitry -- complex networks of reactions and pathways that enable organisms to function. Now, researchers at the California Institute of Technology (Caltech) have built the most complex biochemical circuit ever created from scratch, made with DNA-based devices in a test tube that are analogous to the electronic transistors on a computer chip. More…

BBC News: DNA computer 'calculates square roots'
Los Angeles Times: Research marks a leap forward for DNA-based computers
Nature News: A molecular calculator
Discovery News: DNA computer gets scaled up
Popular Science: Largest DNA-based computer ever built can calculate square roots
Popular Mechanics: The strands of DNA that can calculate square roots
Ars Technica: DNA logic gates calculate square root using 130 different molecules

Winner Take All

Conceptual animation of winner-take-all computation for identifying which memory an unknown input pattern is more similar to. The molecular computation follows the same principle as illustrated, but carried out by a soup of interacting DNA strands.


Fractal Assembly

A brief overview of fractal assembly: a technique for scaling up the size of flat DNA nanostructures with arbitrary patterns.


The seesaw magic book: the computational power of DNA molecules

A whimsical explanation of recent research developing molecular systems that perform information processing tasks. Yes, it's real. No, there's no magic.


Building a tiny "DNA brain"

An animated explanation of recent research building artificial neural networks out of interacting DNA molecules. Part I introduces the motivation, the mathematical model of a neuron, and the design of a DNA-based neural network that is capable of recalling a memory when presented with partial information.

Part II introduces how to make such a DNA-based neural network in the laboratory, how it remembers four scientists and identifies one of them given an incomplete answer to a set of yes-or-no questions, and how this work could be related to the evolutionary history of intelligence.