FLUORESCENCE SPECTROSCOPY BY DETECTION OF

GLUCOSE CONCENTRATIONS IN DMEM-SOLUTIONS AND

ITS PERSPECTIVES FOR NON-INVASIVE MEASUREMENT

O. Abdallah, Q. Qananwah, A. Bolz

Institute of Biomedical Engineering IBT, Karlsruhe Institute of Technology KIT, Karlsruhe, Germany

J. Hansmann, S. Hinderer, and H. Mertsching

Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, University of Stuttgart, Stuttgart, Germany

Keywords: Fluorescence, Biosensors, Non-invasive glucose concentration monitoring, High signal to noise ratio,

Fluorescence spectroscopy, Glucose management, LASER for detection of glucose concentration.

Abstract: An easy accessible and low-cost method for glucose concentration monitoring and diabetes management

will be a great help for more than 250 millions of diabetic patients worldwide to avoid the risks and the

complications caused by hyper- or hypoglycemia. This paper shows the results obtained using fluorescence

spectroscopy for detecting the glucose concentrations in DMEM solutions. By irradiating DMEM solutions

that have different glucose concentrations with light, a few wavelengths in UV- and visible-range for the

calculations of glucose concentrations using fluorescence spectroscopy are applied and the detected signals

were analyzed. For the detection of glucose concentration noninvasively using various optical methods, the

interaction between light and definite glucose solutions was studied. The developed compact system will

enable the application of different LASER diodes (LD`s) or light emitting diodes (LED`s) in the range of

UV and NIR in an easy manner. Variable intensity, frequency and duty cycle can be adjusted for

fluorescence and other optical measurements. A multi-sensor taking all perturbations into account will be a

good choice for glucose monitoring. Fluorescence measurements at wavelengths below 800 nm and

especially the measurements at the wavelength 485 nm give reproducible glucose concentrations results

from DMEM glucose solutions at a constant temperature.

1 INTRODUCTION

Continuous non-invasive monitoring of blood

glucose can achieve a great enhancement by glucose

management to attain a better normal life for

diabetics. Detection of blood contents like Glucose

non-invasively in an easy manner can reduce

morbidity and mortality by diabetics. Design of a

system for the detection of glucose in solutions and

non-invasively can be a great help for diabetics.

Diabetes risk lies in its complications like heart

diseases and infarcts, stroke, blindness, kidney

disease, nerve disease, diabetic foot and amputation.

The current applied invasive methods are

intermittent, inconvenient and painful, having

infection risk, blood loss and time delay, need

consumables materials, needles and strips. The

invasive method cannot be applied continuously, and

hence hypo- or hyperglycemia may be not detected.

A continuous blood glucose monitoring is essential

for glucose management. Noninvasive blood glucose

concentration monitoring will reduce mortality and

morbidity and improve life quality of more than 250

Million diabetic patients worldwide.

1.1 Fluorescence Spectroscopy

Glucose in water shows no fluorescence. In DMEM

solution a glucose dependent autofluoresence can be

observed. The fluorescence differs from the process

of Raman effect in that the incident light is

completely absorbed and the system is transferred to

an excited state from which it can go to various

lower states only after a certain resonance lifetime.

411

Abdallah O., Qananwah Q., Bolz A., Hansmann J., Hinderer S. and Mertsching H..

FLUORESCENCE SPECTROSCOPY BY DETECTION OF GLUCOSE CONCENTRATIONS IN DMEM-SOLUTIONS AND ITS PERSPECTIVES FOR

NON-INVASIVE MEASUREMENT.

DOI: 10.5220/0003176504110414

In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2011), pages 411-414

ISBN: 978-989-8425-37-9

 2011 SCITEPRESS (Science and Technology Publications, Lda.)

Fluorescence spectroscopy and time resolved

fluorescence are now dominant methodologies and

used extensively not only in biochemistry and

biophysics, but also in biotechnology, medical

dioagnostics and genetic analysis (Moschou, 2004,

Pickup, 2005, Lakovics, 2006). The technique is

extremely sensitive. There are increasing examples

of even single-molecule detection using fluorescence

methods. Many studies indicate that fluorescent

technology has real sensitivity especially in low

glucose ranges. In addition, since near-infrared light

passes through several centimeters of tissue, with the

appropriate choice of fluorophore, molecules can in

theory be excited and the emission interrogated from

outside the body providing the potential for

completely non-invasive sensing. A convenient way

of classifying fluorescence-based glucose sensors

that involve measurements of fluorescence is either

according to the type of molecular receptor for

glucose, or whether cells or tissues are used to signal

glucose concentrations and/or glucose metabolism.

A review of the principles of operation and current

status of the various approaches to fluorescence-

based glucose sensing are described in D’Auria,

1999.

2 APPARATUS AND METHOD

The results shown below are obtained using a

fluorescence spectrometer having the

stimulation/emission wavelengths of 360 nm

/465 nm, 430 nm / 535 nm and 485 nm / 535 nm.

The method discussed here will be applied for

invasive and non-invasive measurement.

Photodiodes or phototransistors for fluorescence

detection in the visible and NIR spectrum and light

emitting diodes LED or LASER diodes as light

sources will be applied. Variable frequency and duty

cycle can be adjusted for time resolved fluorescence

signal detection.

The block diagram of the principle of a flexible

developed measuring system is shown in Figure 1.

The developed system is flexible and can be used for

the development purposes, where different

parameters have to be adjusted. Then light

intensities, duty cycle, different LASER types and

variable amplifications can be achieved by using this

system.

Figure 1: Block diagram of an optical sensitive measuring

system.

3 RESULTS AND DISCUSSION

The results obtained below by using a fluorescence

spectrometer show the emitted light by stimulation

of a DMEM solution with different glucose

concentrations. The detected signal with 465 nm by

the stimulation in the UV light at the wavelength of

360 nm is not highly correlated with the glucose

concentration (Figure 2). But an increasing tendency

of the emitted light with the increasing glucose

concentration is shown.

Figure 2: Fluorescence by stimulation/emission

wavelengths of 360 nm /465 nm.

The detected signal at 535 nm shows a high

correlation with glucose concentration when

stimulated with 485 nm (Figure 3). In the contrary to

the detected signals at 465 nm mentioned above, a

decreasing tendency of the emitted light with the

increasing glucose concentration is shown.

Figure 3: Fluorescence by stimulation/emission

wavelengths of 485nm /535 nm.

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Figure 4 shows also a high correlation of the

detected signal at 535 nm with known glucose

concentration when stimulated with 485 nm at

different glucose concentrations. We try here to

obtain a high resolution and accuracy at the lowest

normal level (about 50 g/dl) of glucose

concentrations in order to detect the hypoglycemia.

Also high accuracy has to be achieved around the

glucose concentrations of 180 g/dl in order to detect

hyperglycemia with an acceptable clinical accuracy.

Figure 4: Fluorescence by stimulation/emission

wavelengths of 485nm /535 nm.

Similar relationship between the detected signals

at the wavelength of 535 nm and the glucose

concentrations is shown in Figure 5 for stimulation

at the wavelength 430 nm. A decreasing tendency of

the emitted light with the increasing glucose

concentration is shown in Figure 4 and Figure 5.

Figure 5: Fluorescence by stimulation/emission

wavelengths of 430nm /535 nm.

The detected signal at 535 nm shows in

accordance to other measurements a higher

correlation with glucose concentration and a better

reproducibility when stimulated with 485 nm instead

of 430 nm.

Figure 6: Schematic of a multisensor for non-invasive

detection of blood glucose, hemoglobin concentration, and

fractional oxygen saturation.

The detected glucose signals are too small and

should be processed carefully. Also the in vivo

measurements are subjected to more noise and

motion artifacts. An adaptive filtering will be needed

for eliminating these perturbations. A Noise

Reference Signal is generated by means of a

Synthesizer or piezoelectric element and will be

adjusted as much as possible to the real noise

contained in the corresponding measurement by the

adaptive filter based on the least mean square

optimization algorithm. This algorithm has delivered

very good results by testing it for the non-invasive

calculations of oxygen saturation by artificial

vibrations of the hand, where a pulse oximeter

sensor is applied at the finger subjected to these

artifacts.

4 CONCLUSIONS AND FUTURE

WORK

A non-invasive continuously blood glucose

concentration monitoring will improve the

management of diabetes mellitus. It will be

important for diabetics to avoid the complications

caused by high glucose level in blood. IR-

spectroscopy has the potential for the development

of a simple cost effective sensor for glucose

monitoring that can be used for home care.

Problems with existing methods have

encouraged alternative approaches to glucose

sensing, and those based on fluorescence intensity

and lifetime have special advantages, including

sensitivity and the potential for non-invasive

measurement when UV, visible or NIR light is used

(Yamakoshi, 2006; Evans, 2005; Evans, 2003;

Pickupa, 2005). The fluorescence signals using UV

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FLUORESCENCE SPECTROSCOPY BY DETECTION OF GLUCOSE CONCENTRATIONS IN DMEM-SOLUTIONS

AND ITS PERSPECTIVES FOR NON-INVASIVE MEASUREMENT

413

light as stimulus and detection of fluorescence at

violet or blue have shown a very good correlation

with the glucose concentrations in DMEM solution.

Light stimulation with blue light and the detection of

fluorescence by green region shows also a high

correlation with the glucose concentrations. The

detected glucose signals will be then subjected to

perturbations from the surroundings and from the

background of the measured locations due to tissue

alteration and physiological parameter variations.

All perturbations such as temperature, humidity and

applied pressure variations have to be included by

the calculations, as illustrated by Figure 6.

The drift of the characteristics of the electronic

and optical components may cause high disturbances

to the measurements. The integration of further

parameters may enhance the reproducibility but

decrease the accuracy due to the measurement

errors. The system complexity and the number of the

measured parameters have to be minimized.

There are few fluorescence-based glucose

detection methods that have reached the stage of

testing in vivo, but none have entered clinical

practice for diabetes management. This will be an

area of active investigation in a future work. We will

need to explore different interferences and the

stability as well as accuracy under normal life

conditions.

There is no doubt that fluorescence technologies

have considerable promise for glucose sensing.

As a future work, all developed sensors will be

integrated in one system that enables the

simultenous processing of the detected signals

(Caduff, 2009). Other blood components like total

hemoglobin concentrations and fractional oxygen

saturation measured non-invasively have to be taken

as parameters by the glucose calculations. The

suitable locations for measurements may be earlobe

for transmission measurements or forehead as well

as abdomen for reflection measurements has to be

chosen. Applying the Twersky theory or diffusion

theory by the calculations are our next perspectives.

After that a clinical study for non-invasive

measurements and applying the neural fuzzy

techniques the results and the system will be

optimized.

Using a daily, disposable contact lens embedded

with newly developed boronic acid containing

fluorophores may also be suitable for the continuous

monitoring of tear glucose levels.

ACKNOWLEDGEMENTS

This work is a part of the project „System for Non-

invasive Detection of Glucose “supported by the

Foundation Baden-Württemberg Stiftung by

Research Program: Microsystem technology for the

life sciences. We thank also Dr. Michaela Mueller

and Svenja Hinderer from Fraunhofer Institute

Institute IGB, University of Stuttgart for the

measurements.

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