Fluorescent glucose assays based on the affinity reaction between Concanavalin A and dextran have been extensively studied. However, advancements in polymer science have allowed for new macromolecules capable of replacing dextran which may improve the performance of this well-known assay. Dendrimer macromolecules, being highly ordered and spherical, allow for the binding of specific residues to the terminal (peripheral) binding sites, enabling researchers to customize the molecule. In this research, glycosylated dendrimers have been engineered to replace dextran to allow for more controlled chemical and fluorescent responses (eliminate multivalent binding and improve reversibility). This new assay has been shown to form small aggregate particles containing many Con A and glycosylated dendrimers resulting in a substantial loss in fluorescent intensity. Overall, this assay shows promise for use as part of an implantable glucose monitoring device, but more research needs to be done to increase sensor stability and optimize the sensor response to glucose.

A combined dissolved oxygen and pH sensitive poly(ethylene glycol) hydrogel microarray was fabricated for use in monitoring cell culture media. The sensor was prepared by filling micro-channels with a hydrogel precursor solution containing pH or oxygen sensitive fluorophores. This solution was then cured by passing UV light through a mask placed to the channels, creating array with 100 μm elements. An imaging system with a monochrome CCD camera and appropriate interference filters was used to capture the fluorescence image induced by excitation of microstructure in transmission mode. The sensor performance was characterized in buffer solution (PBS) and cell culture media (MEM) across the biological range of pH (6-8) and dissolved oxygen (3-21%).

Tight control of blood glucose levels has been shown to dramatically reduce the long-term complications of diabetes. Current invasive technology for monitoring glucose levels is effective but underutilized by people with diabetes because of the pain of repeated finger-sticks, the inconvenience of handling samples of blood, and the cost of reagent strips. A continuous glucose sensor coupled with an insulin delivery system could provide closed-loop glucose control without the need for discrete sampling or user intervention. We describe an optical glucose microsensor based on absorption spectroscopy in interstitial fluid that can potentially be implanted to provide continuous glucose readings. Light from a GaInAsSb LED in the 2.2-2.4 μm wavelength range is passed through a sample of interstitial fluid and a linear variable filter before being detected by an uncooled, 32-element GaInAsSb detector array. Spectral resolution is provided by the linear variable filter, which has a 10 nm band pass and a center wavelength that varies from 2.18-2.38 μm (4600-4200 cm^-1) over the length of the detector array. The sensor assembly is a monolithic design requiring no coupling optics. In the present system, the LED running with 100 mA of drive current delivers 20 nW of power to each of the detector pixels, which have a noise-equivalent-power of 3 pW/Hz^1/2. This is sufficient to provide a signal-to-noise ratio of 4500 Hz^1/2 under detector-noise limited conditions. This signal-to-noise ratio corresponds to a spectral noise level less than 10 μAU for a five minute integration, which should be sufficient for sub-millimolar glucose detection.

In this paper, we investigate possibilities of glucose level monitoring in skin