Biosensors long-term implantation

The choice of transducer also depends on the intended tq>plication of the biosensor. If it is to be used in a biological environment, then it must ftilfil the criteria of biocompatibility, especially with regard to the deporition of proteins, lipids, or cells on its surface. If it is to be used in vivo, then it should be of reduced size, and its fcmn adapted so as not to cause excessive damage to living tissues. Furthermore, the possibility of the release of toxic, metallic, or polymeric components from the transducer should be taken into account when long-term implantation of the biosensor is intended. 

Carbon nanotubes are unique materials with specific properties [42]. There is a considerable application potential for using nanotubes in the biomedical field. However, when such materials are considered for application in biomedical implants, transport of medicines and vaccines or as biosensors, their biocompatibility needs to be established. Other carbon materials show remarkable long-term biocompatibility and biological action for use as medical devices. Preliminary data on biocompatibility of nanotubes and other novel nanostructured materials demonstrate that we have to pay attention to their possible adverse effects when then-biomedical applications are considered. 

Yu B, Long N, Moussy Y, Moussy F. A long-term flexible minimally-invasive implantable glucose biosensor based on an epoxy-enhanced polyurethane membrane. Biosensors Bioelectronics 2006, 21, 2275-2282. 

Ju, Y.M., Yu, B., West, L., Moussy, Y, Moussy, F., 2010. A novel porous collagen scaffold around an implantable biosensor for improving biocompatibility. II. Long-term in vitro/ in vivo sensitivity characteristics of sensors with NDGA- or GA-crosslinked collagen scaffolds. Journal of Biomedical Materials Research Part A 92, 650-658. 

In medical sciences research efforts are, e.g., concentrated on long-term working implantable or bloodless measuring sensor probes for rapid measurement of important parameters like glucose and related derivatives [14]. The development of new and tailor-made biosensor components still enables the researcher to broaden the application field of sensors on further analytes and sample matrices [15, 16]. 

Technology used in CGM systems which are currently commercialized or will be commercialized very soon is exclusively based on electrochemical biosensors which measure glucose concentration in ISF or in an ISF extract over a time of up to 14 days. We shall focus on this technology. Readers who are interested in alternative minimally invasive approaches or noninvasive approaches are referred to extensive reviews [222, 223,382]. We shall also not focus on the very interesting topic of long-term sensors, i.e., fully implantable sensors, since they are not yet available commercially. The interested reader may be redirected to a recent review [383]. 

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