Biosensor technology in the treatment of cardiovascular disease - Biomaterials and Devices for the Circulatory System - page 288

disease and hypertension. These diseases are the underlying causes of a
signifi cant number of deaths in the Western world 23 and are on the increase.
The World Health Organization estimated that in 2003 16.7 million people
worldwide died as a result of cardiovascular disease, and predicts this fi gure
will rise to 24 million by 2030 (www.who.int). Electrochemical biosensors
for detecting cholesterol in the blood mostly employ cholesterol oxidase
or cholesterol esterase as their biological element. A wide range of choles-
terol biosensors have been reported to date, using a range of matrix, immo-
bilisation and transducer technologies. 5 Several commercial cholesterol
biosensors are currently available (often combined with glucose measure-
ment functions), including AccuTrend by Roche Diagnostics (Basel,
Switzerland) and CardioChek by Polymer Technology Systems (Indiana,
USA).
In addition to biochemical markers, emerging technology allows genetic
markers of cardiovascular disease to be quantifi ed. DNA microarray analy-
sis techniques are available for making measurements of differential gene
expression and variations in gene sequencing, as shown in Fig. 11.6. Thou-
sands of probes, including cDNA, RNA and plasmids, are spotted onto

Microarray, containing
labelled probes for
thousands of different
DNA sections

DNA/RNA from
clinical sample
added to array

Hybridisation

Detection by
fluorescence/radioactive
techniques produces a map
of signal intensity

￿ ￿ ￿ ￿ ￿

Translation of signal intensities
into levels of individual gene
expression

11.6 Microarray for the simultaneous quantifi cation of the expression
of thousands of genes.