Tissue-Integrated Sensitive Glucose Nanosenor Using Inactive Glucose Oxidase Enzyme
Monitoring glucose levels is one of the key elements in health
monitoring. A research team has now developed a battery-independent
fluorescent nanosensor based on single-wall carbon nanotubes and an
inactive form of the enzyme glucose oxidase (GOx). Because the enzyme is
not in its active form, the analyte is not consumed during the
measurement, and continuous, reversible, and non-invasive bioimaging of
glucose levels in body fluids and tissues is possible, the team reports
in the journal Angewandte Chemie.
Blood glucose levels are
typically measured using GOx-based electrochemical sensors. However,
these sensors produce toxic hydrogen peroxide as a byproduct and,
furthermore, require bulky electrical circuits and batteries, making it
difficult to prepare implantable devices for continuous measurement.
Tiny SWCNTs, on the other hand, can be integrated into tissues and
provide bioimaging information: when excited by light, SWCNTs produce a
near-infrared fluorescence signal that travels through tissue and can be
easily recorded using non-invasive bioimaging techniques.
© Wiley-VCH, re-use with credit to 'Angewandte Chemie' and a link to the original article.
Unfortunately, making GOx-based SWCNT nanosensors is difficult
because the most effective technology for loading molecules onto
SWCNTs—sonication—essentially inactivates the GOx molecules. Now,
Markita P. Landry and her research team at the University of California
in Berkeley, USA, have disproved the assumption that GOx-based sensors
require active GOx for successful glucose sensing. Using sonication,
they prepared GOx-loaded SWCNT sensors that reliably, selectively, and
sensitively detected glucose, as demonstrated for glucose measurements
in serum, plasma, and mouse brain slices.
The researchers explained this surprising finding by the ability of
the inactive GOx enzyme to bind glucose without converting it. Binding
alone was sufficient to modulate the fluorescence signal. To be
completely independent of GOx activity, the researchers also constructed
a GOx enzyme that even lacked the reactive group for glucose
conversion. The resulting apo-GOx-SWCNT sensor detected glucose in body
fluids and mouse brain slices as reliably as the original conjugate of
SWCNT and natural GOx.
The researchers point out that the use of inactive GOx molecules has
major advantages. For example, the manufacturing process of the
GOx-SWCNT nanosensors can be simplified by using sonication as an
effective preparation step. In addition, as the analyte is not consumed
by the enzyme reaction, no toxic byproducts are produced, and the
measurements are intrinsically reversible, allowing for non-invasive
continuous glucose monitoring in tissue fluids.
(2738 characters)
About the Author
Dr. Markita Landry
is an Associate Professor of Chemical and Biomolecular Engineering at
the Berkeley College of Chemistry, University of California, Berkeley,
USA. The Landry Lab's work develops synthetic biomimetic nanocomposites
to impart control over nanomaterial interactions with biological systems
for applications in molecular imaging and targeted biodelivery.
Copy
free of charge—we would appreciate a transcript/link of your article.
The original articles that our press releases are based on can be found
in our online pressroom.