Biomedical Engineering Reference
In-Depth Information
In the following sections the use of biosensors for the detection of disease-
related biomarkers is demonstrated. Sample dilution has often been reported as
means to reduce nonspecific binding, despite the fact that mostly small biomarker
concentrations have to be detected. This leads to high demands regarding the
biosensor systems.
Four application areas were chosen to show the performance of biosensors
dealing with real samples:
• Cardiac biomarkers in serum. They may be a sign of, e.g., myocardial infarction
and therefore require a fast and reliable detection.
• Serum biomarkers for cancer and autoimmune disorders. Chronic diseases
require early diagnosis as well as regular control of certain biomarkers, i.e., a
reliable and low-cost detection method would be beneficial.
• Biomarkers in CSF for neurodegenerative diseases. Early diagnosis and treat-
ment would allow delay of severe symptoms, i.e., a reliable and low-cost
detection method would be beneficial.
3.2 Detection of Cardiac Biomarkers
3.2.1 Cardiovascular Disease Diagnostics
Globally, CVDs are the main cause of death [
102
]. Among acute coronary syn-
dromes, myocardial infarction, commonly referred to as ''heart attack,'' is one of the
most life-threatening forms, as it quickly causes irreversible damage to the heart.
Therefore, it has to be diagnosed as soon as possible, e.g., by means of an electro-
cardiogram or by determination of concentrations of cardiac specific biomarkers,
such as troponin and myoglobin. C-reactive protein (CRP) may also be detected;
however, this marker is rather used for monitoring the risk of recurrence of myo-
cardial infarction [
103
]. As previously reviewed, commercially available POCT
devices exist which are able to determine the acute phase biomarkers within 5-20
min assay time in the required concentration ranges. Most of them are based on
immunoassay or immunochromatographic test methods using fluorescence or che-
miluminescence detection allowing the determination of several cardiac biomarkers
within one measurement cycle. However, the integration of those devices in clinical
routine—and thus their acceptance—is still low, mostly due to cost restraints and
because clinical cutoff values have not yet been established [
103
]. Therefore, as
biosensors provide the possibility for low-cost analysis, they could still find their way
in this field of application. This will be demonstrated in the following by examples of
biosensors for the detection of the cardiac biomarkers troponin, myoglobin, and
CRP. The biosensors presented are immunosensors, i.e., antibodies were immobi-
lized as analyte-specific biorecognition elements on the transducer surfaces.
