Biosensors implanted

Justin, G., Finley, S., Rahman, A.R., and Guiseppi-Elie, A. (2009) Biomimetic hydrogels for biosensor implant biocompatibility electrochemical characterization using micro-disc electrode arrays (MDEAs). Biomedical Microdevices, 11 (1), 103-115. 

New natural polymers based on synthesis from renewable resources, improved recyclability based on retrosynthesis to reusable precursors, and molecular suicide switches to initiate biodegradation on demand are the exciting areas in polymer science. In the area of biomolecular materials, new materials for implants with improved durability and biocompatibility, light-harvesting materials based on biomimicry of photosynthetic systems, and biosensors for analysis and artificial enzymes for bioremediation will present the breakthrough opportunities. Finally, in the field of electronics and photonics, the new challenges are molecular switches, transistors, and other electronic components molecular photoad-dressable memory devices and ferroelectrics and ferromagnets based on nonmetals. 

FIGURE 3.5 Design of an implantable three-layered glucose biosensor for subcutaneous monitoring (based on [15]). 

M. Schlosser and M. Ziegler, Biocompatibility of active implantable devices, in Biosensors in the Body Continuous In Vivo Monitoring (D.M. Fraser, ed.), pp. 139-170. John Wiley, NY (1997). 

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. 

The development of biosensors is expected to benefit monitoring therapeutic drug levels, office testing, and implantable devices because of the advantages of cost-saving automation and improved data handling... 

Gifford R, Kehoe JJ, Barnes SL, Komilayev BA, Alterman MA, Wilson GS. Protein interactions with subcutaneously-implanted biosensors. Biomaterials 2006, 27, 2587-2598. 

CholeauC, Klein JC, Reach G, AussedatB, Demaria-Pesce V, Wilson GS, Gifford R, Ward WK. Calibration of a subcutaneous amperometric glucose sensor implanted for 7 days in diabetic patients. Part 2. Superiority of the one-point calibration method. Biosensors Bioelectronics 2002, 17, 647-654. 

Biosensor-tissue compatibility is a significant obstacle in the development of viable, enduring implantable biosensors.1,2 The clinical literature and product development files in industry are littered with biosensor failures in many different sites and... 

Wisniewski N, Moussy F, Reichert WM. Characterization of implantable biosensor membrane biofouling. Fresenius Journal of Analytical Chemistry 2000, 366, 611-621. 

These results should be contrasted with the situation with sensors that were implanted over 30 days. The lag in these devices rose to 15-30 min. There was also a decline in sensitivity of the sensors to glucose, sensor accuracy, and the degree of closed-loop glycemic control.4 Based on the known effects and time course of collagen deposition that occurs as part of the foreign body reaction,12 13 it is very likely that this decline in sensor function was a direct result of this process. The effect of the foreign body reaction on the function of biosensors has been comprehensively reviewed by Wisniewski and colleagues.14 15... 

Figure 3.2 The effect of prolonged subcutaneous implantation on biosensor function. Blood glucose values shown in solid circles and glucose sensor values in the continuous lines. The early study (top panel), but not the late study (bottom), shows excellent sensor accuracy and minimal lag between blood glucose and sensed glucose values. MARD (mean absolute relative difference) refers to a sensor accuracy metric. EGA refers to the Clarke error grid analysis accuracy metric.

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