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                   Point-of-care biosensors

Biosensors combine a molecular recognition element with a signal conversion unit. Some biosensos have been successfully commercialized for clinical applications such as electrochemical blood glucosesensors. Molecular biosensors are more preferred as a clinical diagnostic tool than other methods partically because of real-time measurement, rapid diagnosis, multi-target analyses, automation, and reduced costs. As a recent advance in molecular biology has led to our better understanding of potential disease-related protien biomarkers and DNA mutations, biosensors became a promising technology for early diagnosis. Two different molecular sensing techniques are generally employed: (1) a "lock-and-key" approach to detect a specific analyte and (2) a "cross-reactive" or "pattern-generation" technique to monitor the overall levels of molecules. The ¡°lock-and-key¡± design immobilizes a specific bio-receptor on a sensing surface, which enables the surface to form a strong and specific chemical bond with target analytes.  In practice, however, many biosensors based on the ¡°lock-and-key¡± design suffer from interference caused by molecules that are structurally or chemically similar to the desired analyte. This is an unavoidable consequence of the ¡°lock¡± being able to fit many imperfect ¡°keys¡±. Additionally, biomarkers themselves are an imperfect measure, as many biomarkers are non-specific to particular diseases, and most diseases have more than one biomarker associated with their incidence. Furthermore, concentration changes of biomarkers in serum may cause unexpected interactions with other proteins making their detection very challenging, as in the case of prostate antigen serum, for example. These challenges lead to adopt total biomolecular distributions, rather than aiming to detect a specific molucule, in serum for disease diagnosis. The ¡°cross-reactive¡± technique has been developed as an alternative approach for this purpose. This method is inspired by the senses of taste and smell, and utilizes an array of differentially responsive receptors to create response patterns to detect target analytes when they are present at elevated levels in media. The distinct advantage of the "cross-reactive" method is that the individual receptors do not need to be highly specific or selective to an analyte unlike the ¡°lock-and-key¡± method, which also requires time-consuming and labor intensive synthesis and design of the receptors. We currently focus on developing a biosensor based on "cross-reactive" technique.