Medical Design Briefs - October 2022 - 42

enzyme & coenzyme embedded electrospinning
lypholized
ADH & NAD+
polymer sol.
+
+
+ +
high voltage
source
collector electrode
ready-to-use (w/o treatment)
UV-LED
BPFex
LPFfl
camera
-15 s
0 s
5 s
95 s
× 3000
+
+
eFES mesh
ex.
+ EtOH
no fl.
NADH
fl. emission
0.5
0.4
0.3
0.2
0.1
gaseous ethanol
00.5
1.01.5
time after applying EtOH (min)
The electrospinning enzyme string was made with enzyme and coenzyme containing water-soluble
polymer solution (top). The fabricated electrospinning fluorometric enzyme string (eFES) mesh was set
on
fluorescence
imaging system without
pretreatment (bottom-left).
a wet condition so that they do not become
denatured and lose their ability
to catalyze reactions.
Now, a collaborative team of researchers
from Tokyo Medical and
Dental University (TMDU) and Waseda
University led by Professors Kohji
The images
and numerical
of enzyme reaction rate when applying ethanol vapor to the eFES mesh (bottom-right). (Credit: Elsevier)
Mitsubayashi and Naoya Takeda created
a noninvasive biosensor for volatile
organic compounds in the form of a
solid mesh. A solution of polyvinyl alcohol
was first combined with the enzyme
alcohol dehydrogenase and the
coenzyme nicotinamide adenine. The
values
mixture was forced through a nozzle at
a high voltage. Thin fibers of polymer
accumulated on the collector plate,
with the enzyme embedded inside,
until a solid mesh was obtained. The
presence of ethanol vapor could be detected
based on a significant increase
in fluorescent activity.
" We found that immobilizing the
enzymes inside the mesh preserved
their activity, even under ambient conditions, "
author Misa Nakaya says. The
researchers performed tests to determine
the optimal pH conditions and
evaluated the relationship between
fluorescence intensity and applied ethanol
quantity. They also found that the
biosensor's fluorescence was not triggered
when exposed to other volatile
compounds, such as acetone or methanol,
so specificity was maintained.
" Our dry-form biosensor for detecting
chemicals in the air will have a
much better chance at obtaining widespread
commercial adoption because
of its ease of fabrication, " says author
Kohji Mitsubayashi. Having the capacity
to produce solid biosensors quickly
and cheaply may enable new point-ofcare
diagnostics and environmental
monitoring systems for use in the field.
The research is published in Biosensors
and Bioelectronics as " Enzymeembedded
electrospun fiber sensor of
hydrophilic polymer for fluorometric
ethanol gas imaging in vapor phase "
(DOI:10.1016/j.bios.2022.114453).
For more information, visit www.tmd.
ac.jp. Contact: Dr. Kohji Mitsubayashi,
m.bdi@tmd.ac.jp.
Powering an 'Arm' with Air Could Be Mighty Handy
Walking feeds pressure
to pneumatic robots that
could help those with
disabilities.
Rice University
Houston, TX
Mechanical engineers have built a
handy extra limb able to grasp objects
and go, powered only by compressed air.
It's one of several ideas the engineers at
Rice University's George R. Brown School
of Engineering have implemented with a
textile-based energy harvesting system.
42
The proof-of-principle robotic devices
designed and built by Daniel Preston,
an assistant professor of mechanical engineering,
lead authors Rachel Shveda
and Anoop Rajappan, and their team are
geared toward those living with disabilities
and are tough enough for everyday
use, they say. The project described in
Science Advances utilizes air differs from
the Preston lab's now-famous manipulation
of dead spiders as grabbers: these
pneumatic devices derive their power
from walking.
The prototype " arm " is a piece of fabric
that hugs the body when not in use
www.medicaldesignbriefs.com
but extends outward when activated and
incorporates an elastomer lining on the
surface to maintain its grip on slippery
objects. For demonstrations, Rice alumna
Shveda, now an officer in the U.S.
Coast Guard, would operate the arm
with a switch. Preston says future versions
could have sensors that anticipate
the wearer's intent and complete the
movement.
In addition to the curling arm that can
grip a cup or other small objects while
one's hands are full, the Rice lab built a
shirt with a bellows-like actuator attached
at the armpit that expands, enabling the
Medical Design Briefs, October 2022
differential (a.u.)

http://www.tmd.ac.jp http://www.tmd.ac.jp http://www.medicaldesignbriefs.com

Medical Design Briefs - October 2022

Table of Contents for the Digital Edition of Medical Design Briefs - October 2022