New graphite based rapid sensor chip for real-time theophylline
monitoring

Date:
April 26, 2022
Source:
Shibaura Institute of Technology
Summary:
Although theophylline (THO) is effective in treating respiratory
problems and inflammation, the drug can be toxic if taken above
certain limits.

This demands accurate and rapid sensing devices that can closely
monitor THO levels in patients. Therefore, scientists have now
designed a paper- based THO sensor with a response time of 3
seconds. This new sensor is highly selective and sensitive. It
has also been successfully tested using whole bovine blood.



FULL STORY ========================================================================== Theophylline or THO is a natural organic compound whose molecular
structure is very similar to that of caffeine present in coffee and
cacao. Over the years, due to its therapeutic properties, THO has become
one of the most widely studied xanthine group derivates. THO is used
to dilate respiratory passages in people having difficulty breathing,
and as a muscle relaxant, anti-asthmatic, and diuretic (drugs used to
increase urine production and reduce blood pressure). It is also known
to have anti-inflammatory and anti-tumor properties, and can regulate
our immune responses too.


========================================================================== While THO is beneficial in treating a number of conditions, the drug has
a very narrow therapeutic window. This means it can create adverse effects
if administered beyond a certain limit (and that limit can be quite easily reached). An accidental or deliberate overdose can be highly toxic and
lead to problems such as seizures, rapid heartbeats, excitation of the
nervous system, or even death. This makes close monitoring of THO levels
during therapy extremely crucial. In a recent breakthrough article --
which was published in Volume 27, Issue 8 of Molecules, made available
online on 11 April 2022 -- a team of researchers from Shibaura Institute
of Technology (SIT) in Japan describe how they developed a low cost and
rapid electrochemical sensor for THO detection. Elaborating on their
motivation for the study, Prof. Yasuo Yoshimi (who is the corresponding
author of the article) says, "Conventional drug monitoring relies on laboratories outside the hospital to analyze the molecular levels of drugs
in blood. Our reagentless sensing tool can easily detect THO directly
from whole blood in less than 3 seconds, just like a glucose sensor."
This article is a part of the journal's special issue titled "Molecularly Imprinted Polymers: Impactful Technology vs. Academic Exercise."
Therapeutic drug monitoring is essential for optimizing the effects
of treatments such as chemotherapy, which require strict control over
the drug's concentration in the patient's blood to prevent severe side
effects. However, most monitoring techniques are often time-consuming and demand complex procedures that can only be carried out by an expert. The
same goes for THO detection methods.

To alleviate these problems, researchers over the years have developed
low-cost electrochemical methods that are simple, highly sensitive, and
rapid. One of these, a class of electrochemical tools that has recently
gained momentum, is molecularly imprinted polymers (MIPs). These
tools have tailor-made molecular cavities that can recognize and
bind to specific target molecules, just like receptors in our own
body would. Their ability to do so is being widely used in several applications, including drug detection.

In this study, the team of scientists developed a disposable, paper-based
THO sensor consisting of an electrode made of molecularly imprinted
graphite. Since MIPs are designed using the target molecule as a template,
the team used THO as a template when developing the sensor's carbon-based electrode paste. The synthesized paste was then loaded onto a printed
sensor chip and its THO detection abilities were tested.

The sensor was found to be highly sensitive (meaning it could detect
even small amounts of THO) and showed great selectivity towards the
drug. In fact, the sensor could identify THO even in samples with THO concentrations as low as 2.5 myg/mL ( myg=microgram, i.e., 1/1000 of a milligram). And what's more, this sensor needs only 3 seconds to detect
THO! It could do so even in whole bovine blood.

This portable, low-cost, reliable, and rapid sensor has long-term
stability and can be used for the real-time detection of drugs like
THO without us depending on sophisticated equipment. Furthermore,
the fabrication strategy provided in this study can be used to
develop efficient electrochemical sensors for various other clinical interventions. Assistant Prof. Aaryashree (who is the first author of
the article) concludes, "Existing methods for the analysis of the drugs
in blood are expensive and need specialized equipment. This can be a
problem for developing countries dealing with a lack of resources and technicians. The paper-based sensor that we have developed is not only
easy to use but also economical and can reduce the burden of drug analysis
in developing countries. Further, its prototype can be used to develop
a bedside therapeutic drug monitoring system, which will alert us of any overdose, avoiding side effects in patients taking these drugs,." Indeed,
a useful innovation!

========================================================================== Story Source: Materials provided by
Shibaura_Institute_of_Technology. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Aaryashree, Tomoji Ohishi, Yasuo Yoshimi. A Disposable Sensor
Chip Using
a Paste Electrode with Surface-Imprinted Graphite Particles for
Rapid and Reagentless Monitoring of Theophylline. Molecules, 2022;
27 (8): 2456 DOI: 10.3390/molecules27082456 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220426101638.htm

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