news
Science | DOI: 10.1145/2043174.2043180
Kirk L. Kroeker
the Rise of
molecular machines
The field of molecular computing is achieving new levels of control
over biochemical processes and fostering sophisticated connections
between computer science and the biological sciences.

TakiNG CUes FroM both spec- ulative fiction and hard sci- ence, today’s most prolific futurists have envisioned a point in the future when developments in genetics, nanotechnology, and robotics make it possible to sidestep the constraints of human durability and intelligence. Controversial assumptions notwithstanding, even the most optimistic speculation about the future symbiotic convergence of humans and technology is deriving at least some measure of credibility from emerging work in molecular computing. Researchers in this field are achieving new levels of control over biological processes and fostering sophisticated crossovers between computer science and the biological sciences.

In one recent development, scientists in the department of molecular computing at the California Institute of Technology (Caltech) have built what they are calling the most complex biochemical circuit ever created from scratch. These circuits, the Caltech researchers say, will allow scientists to explore the principles of information processing in biological systems and design biochemical pathways with

Wiring diagram specifying a biochemical circuit that consists of 74 different dna molecules. the circuit, developed at Caltech, demonstrates an approach for implementing arbitrary digital logic in biochemical systems. the lines correspond to single-stranded oligonucleotides, while the nodes correspond to partially double-stranded molecules.

 

decision-making capabilities. Such circuits, they say, will give biochemists unprecedented control over chemical reactions for biological and chemical engineering and may even lead to the proliferation of molecular-scale biological machines.

Lulu Qian, a senior postdoctoral
scholar in bioengineering at Caltech,
and Erik Winfree, a Caltech profes-
sor of bioengineering and computer
science, computation, and neural sys-
tems, used DNA-based components to
build the circuit. Instead of depending
on electron flows through transistors,
the DNA logic gates receive and pro-
duce molecules as their signals. The
molecular signals travel from one gate
to another, connecting the circuit as if
the molecules were wires.