Continuous real-time in-vivo monitoring

In an attempt to improve the selectivity of local dopamine measurements in the complex extracellular matrix of brain fluid, an implantable enzyme-based dopamine microbiosensor has been constructed based on the immobilization of tyrosinase in a thin-film chitosan coating of carbon-fiber disc microelectrodes [357]. o-Dopaquinone, which is the product of the tyrosinase reaction with dopamine, was monitored via its reduction at the modified microelectrode surface. The application of these cathodic tyrosinase dopamine microbiosensors was reported for the continuous real-time in vivo visualization of electrically stimulated dopamine release in the brain of anesthetized laboratory rats. Remarkably, due to the cathodic potential the sensor response was not significantly disturbed by the presence of typical interferences such as ascorbic and uric acid, serotonin, norepinephrine, and epinephrine. 

However, despite these drawbacks, one of the greatest advantages of the coupling of microdialysis with biosensing techniques is the unique opportunity offered for continuous monitoring of a given analsde in real time, both in vivo and in vitro. 

The predominant application of biosensors is in the biomedical field which has a constant need for monitoring biological parameters in health care techniques. The biosensor is particularly suitable for such measurements because a sample can be analysed in a complex biological environment without the need for chemical reagents. Biosensors can be used in vivo and, because they give a continuous signal, can monitor metabolite concentrations in real time. Hence their important application in the control of blood sugar in diabetics. 

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