1
Supporting information
S
elf
-
P
ropelled
C
hemical
-
P
owered
P
lant
-
T
issue Biomotors
Yonge Gu, Sirilak Sattayasamitsathit, Kevin Kaufmann, Rafael Vazquez
-
Duhalt,
Wei Gao,
Chunming Wang,
Joseph Wang*
Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA
E
-
mail:
josephwang@ucsd.edu
Supporting
Video
C
aptions
SI video 1
:
Self
-
propelled plant tissue
motors
:
potato coated with epoxy
resin
, carrot coated with
chitosan and millet sputtered with Ti.
SI Video 2
:
Uncoated potato rods in different concentrations of H
2
O
2
: a) 0%, b) 5% c) 10%.
SI video 3
:
Potato
motors with different coatings (from left to right and
top to bottom): epoxy
resin
,
nail
lacquer,
N
afion, and chitosan.
SI video 4
:
The effect of
H
2
O
2
concentration on the performance of the potato motors.
SI Video 5
:
The effect the temperature on the functionality of potato motors.
SI video
6
:
Thermostability of potato rods.
Experimental
Section
Materials
Potato tuber
(
Solanum tuberosum
)
, carrot root (
Daucus carota
) and millet (
Panicum
miliaceum
) were purchased from a lo
cal market. Hydrogen peroxide
,
sodium dodecyl sulfate
(SDS) and chitosan were purchased from Sigma
-
Aldrich. Nafion and epoxy resin were obtained
from
Fluka and Devcon, respectively.
Tissue
Biomotors
Preparation
Plant tissue motors were designed in a way that would attempt to maximize th
e number of active
sites on the rocket that would not produce competing forces since too many equal and opposite
forces would result in no net movement when placed in H
2
O
2
. The initial plant tissue motor
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This journal is © The Royal Society of Chemistry 2013
2
structure was created by cutting on cross section of
potato and carrot with a ~2 mm thickness.
Small cylindrical motors were punched out of the plant cross section
using a 1.0 mm
-
diameter
Harris puncher
(Redding, CA)
. The small cylindrical tissue structures was then covered with
epoxy
resin
, nail lacquer,
Nafion or 0.5% w/v chitosan, providing
as inert coating for creating an
asymmetric structure. The
asymmetric
propulsion forces resulted from the catalase catalyzed O
2
generation in H
2
O
2
solution.
In order to make
asymmetric millet rice motors, millet beads
were sputtered with Ti to create
Janus structures. A benefit of this method is the ability to precisely control the coverage area of
each motor.
Tissue
motor
propulsion
In order to propel biocatalytic tissue motors,
aqueous hydrogen peroxide solutions we
re used as
chemical fuels. All solutions contained 1.0% (w/v) sodium dodecyl sulfate (SDS) to reduce the
surface tension, hence facilitating the tissue motors propulsion.
The propulsion of the tissue
motors was tested in various H
2
O
2
concentrations (1%,
10%, and 30%). For each set of conditions,
coated and non
-
coated motors were immersed into the H
2
O
2
solution. The bubble generation and
movement of the tissue motors were recorded using an iPhone
4S
camera.
Millet motors were
sputtered with Ti using Emitec
h K575X Sputter Coater.
Evaluation of the
Catalase activity
The activity of plant tissue motors
w
as
estimated
by measuring
oxygen generation
using a
manometer
(
UEi EM151
e
lectronic
m
anometer
, OR, USA)
attached to a sealed bottle
containing
a
specific H
2
O
2
concentration.
The
effect of concentration of
H
2
O
2
on catalase activity of plant rods
was determined.
T
he cata
lase activity is reported as U/rod of
tissue in which the e
nzymatic units
were defined as μ
moles of O
2
produced per minute per plant tissue
mot
or
.
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This journal is © The Royal Society of Chemistry 2013
3
SI Fig. 1
Bubble generation from potato
rods
in different H
2
O
2
concentrations
(A) and times (B).
Peroxide concentration (A):
a) 0%, b) 5% c) 10% and d) normalization intensity of bubbles
generated as a function of H
2
O
2
concentration
.
(Images were taken after
being subjected for
10 s to
H
2
O
2
solution in Video 2
); B)
B
ubble generation from potato motors in 10% H
2
O
2
following: a) 0,
b) 10, c) 20
s and d) normalization intensity of bubbles gene
rated as a function of time
.
Scale bar is
3mm
SI
Fig
.
2
Evaluation of the catalase activity of
per small tissue rod or seed
: a) millet, b) potato and
c) carrot in different H
2
O
2
concentrations.
a
a
b
c
a
a
b
c
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This journal is © The Royal Society of Chemistry 2013
4
SI Fig.
3
Time
lapse images of potato motors with different coatings in 10% H
2
O
2
: A) epoxy
resin
,
B) nail lacquer, C) 5% Nafion and D) 0.5% (w/v%) chitosan.
Images were taken
from
SI Video 3
after
a 5
s expos
ure
to H
2
O
2
solution.
SI Fig.
4
Bubble generation by
the potato tissue
:
10 (A)
and 20 (B) min storage at 50°C, along with
the behavior of the untreated tissue (C).
Images were taken
from SI Video 4
after
a 5
s expos
ure
to
10%
H
2
O
2
solution at room temperature.
Electronic Supplementary Material (ESI) for Chemical Communications
This journal is © The Royal Society of Chemistry 2013