Angewandte
Chemie
DOI: 10.1002/anie.201107733
Molecular Devices
An Autonomous and Controllable Light-Driven DNA Walking
Device**
Mingxu You, Yan Chen, Xiaobing Zhang,* Haipeng Liu, Ruowen Wang, Kelong Wang,
Kathryn R. Williams, and Weihong Tan*
The development of nanotechnology has been largely
inspired by the biological world. The complex, but well-
organized, living system hosts an array of molecular-sized
machines responsible for information processing, structure
building and, sometimes, movement. Molecular motors are
tiny protein machines that power motion in the cellular world,
for example, myosins moving on actin filaments and dyneins
or kinesins walking along microtubule tracks.[1]
Artificial DNA-based motors have recently emerged to
mimic molecular motors[2] and to perform tasks in cargo
transport[2e] and biosynthesis.[2f] The programmable assembly
and simplicity of polynucleotide interactions have made
DNAs suitable for the control of progressive and directional
movement at the molecular level. However, energy supply is
a major concern for any motor.[3] Biological molecular motors
employ free energy based on the binding and hydrolysis of
ATP, whereas artificial DNA walkers have previously
explored energy supplied by DNA hybridization[4] or hydrol-
ysis of either the DNA/RNA backbone[5] or ATP molecules.[6]
These artificial walking devices are still in their infancy, and
they are not as powerful as their protein counterparts from
nature. Still, identification of new types of energy supplies
could play a major role in the development of the next-
generation mechanical robots.
these biological motors are considered to be autonomous. For
artificial DNAwalkers, however, nonautonomous locomotion
by regular addition of fuel[7] is always much simpler from
a design standpoint, compared to an autonomous device. On
the other hand, the capability of autonomous motion some-
times results in decreased controllability[2,5,6] because the
device cannot be stopped at a desired position or time, or once
stopped, it cannot be easily restarted. Therefore, construction
of free-running and autonomous “true” molecular motors,[2b]
in comparison to nonautonomous designs, is still essential to
the operation of nanomachines that mimic biological func-
tion. The availability of such an easily controllable, free-
running DNA walker would also be significant for the future
design of nanorobots to perform multiple and complex
functions.
We report here a new light energy-powered DNA walker
capable of regulated autonomous movement along a nucleic
acid track. It has been widely known that photochemical
energy sources can serve as inputs for molecular-level
switches in the operation of nanomachines.[8] We recently
found that aromatic hydrocarbons (e.g., pyrene molecules)
can efficiently facilitate the photolysis of disulfide bonds
within artificial nucleic acid backbones[9] and that a catalytic
cleavage function could be achieved through the design of
pyrene-incorporated DNAzyme analogues (Figure 1a). This
same pyrene-assisted photolysis reaction is also a major
component of our DNA walker design (Figure 1b).
Biological motors normally operate in a constant environ-
ment without external intervention, and they remain in
operation as long as a source of energy is available. Thus,
Photon radiation, which is virtually unlimited, supplies the
energy (together with DNA hybridization free energy) for
this type of nanomachine, and the amount of energy input to
operate such machines can be readily controlled by using
different intensities of excitation light. Moreover, by taking
advantage of recent developments in laser and near-field
techniques, high spatial and temporal resolution can be
achieved from light control as well.[10] With its renewable
energy supply, we envision that the light-powered DNA
walker will allow us to precisely control the speed and motion
of nanorobots and, hence, advance the progress of molecular
biology in the future. This work represents the first light-
powered DNA walking devices able to achieve controllable,
autonomous, and directional movement, and it expands the
scope of energy supplies available to power nanosized
motion.
[*] M. You, Dr. Y. Chen, Dr. H. Liu, Dr. R. Wang, Dr. K. Wang,
Dr. K. R. Williams, Prof. Dr. W. Tan
Department of Chemistry and Physiology and Functional Genomics
Center for Research at the Bio/Nano Interface
Shands Cancer Center, UF Genetics Institute
and McKnight Brain Institute, University of Florida
Gainesville, FL 32611-7200 (USA)
E-mail: tan@chem.ufl.edu
Prof. Dr. X. Zhang, Prof. Dr. W. Tan
State Key Laboratory for Chemo/Biosensing and Chemometrics
College of Biology and College of Chemistry and Chemical
Engineering
Hunan University, Changsha 410082 (P.R. China)
E-mail: xiaobingzhang89@hotmail.com
[**] The authors would like to thank the Interdisciplinary Center for
Biotechnology Research (ICBR) at the University of Florida for
technical support. This work is supported by grants awarded by the
National Institutes of Health (grant numbers GM066137,
GM079359, and CA133086) and by the NSF. This work was also
supported by the National Key Scientific Program of China
(2011CB911001, 2011CB911003).
The walking system consists of three parts: a single-
stranded DNA track (T), four anchorage sites (S1, S2, S3, and
S4), and a light-sensitive walker (W, Figure 1). Similar to
previous design of processive walker by He et al.,[2f,5a] the
track contains four 21-nucleotide binding regions that are
complementary to the recognition tag of the respective
Supporting information for this article is available on the WWW
Angew. Chem. Int. Ed. 2012, 51, 2457 –2460
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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