Microdialysis and glucose biosensor for in-vivo monitoring

Microdialysis coupled to a glucose biosensor led to a continuous monitor system in vivo for glucose. Several microdialysis probes were used to stabilize the biosensor response. In vivo experiments, especially when the probe was placed subcutaneously, showed that the sensitivity of the biosensor decreased continuously; various kinds of fibers with a molecular weight cut-off (MWCO) ranging from 6 000 to 20 000 were compared. A wall-jet flow cell as detector for glucose showed less interference when compared to a thin layer cell. Glucoday, a new commercial instrument based on this principle, is presented

A Rapid Enzymatic Method for Aflatoxin B Detection

A novel method for aflatoxin B (AFB) determination is proposed. The AFB determination is based on acetylcholinesterase (AChE, from electric eel) inhibition, and the AChE residual activity is determined using the colorimetric method (Ellman's method). To select and optimize the analytical procedures, the investigation on type of AChE inhibition by AFB(1) was carried out. The AChE degree of inhibition by AFB(1) was independent of the incubation time and the enzyme concentrations, showing the reversibility of the inhibition. This reversibility of the inhibition permits a rapid analysis of AFB(1). In fact, only a 3-min analysis is required. For the development of AFB(1) assay, the pH, the reaction time, the temperature, and the substrate concentration were evaluated and optimized. The linear range of 10-60 ng/mL was assessed. To evaluate the selectivity of this method, the cross-reactivity with other aflatoxins, such as AFB(2) (aflatoxin B(2)), AFG(1) (aflatoxin G(1)), AFG(2) (aflatoxin G(2)), and AFM(1) (aflatoxin M(1)), was investigated. The suitability of the assay for AFB(1) quantification in barley was also evaluated. This study shows a new approach to detect aflatoxins based on enzyme inhibition with several advantages, such as the easiness of use, the rapidity, and the cost-effectiveness, demonstrating a possible use as screening method for this type of mycotoxins

Biosensors for non-invasive measurements

Demand for non-invasive, fast, real-time and inexpensive analyses in humans is increasing. In particular, measurements of metabolites in media other than blood are particularly important for patients who have to control daily parameters such as glycemia and urea, and for people who have problems collecting blood. Although many sampling sites are available for non-invasive sensing, until now most efforts have concentrated on saliva, sweat, and the human skin itself. In this chapter, we detail examples of non-invasive measurements of metabolites of clinical interest, other than glucose, present in saliva and sweat that correlate well in bloo