2. Analysis of Glucose, Cholesterol and Uric Acid

This chapter describes the devices destined to quantify glucose, uric acid and cholesterol in biological samples with both colorimetric and electrochemical detection which were proposed in the course of this work. Glucose is one of the most critical for life compounds found in nature; clinically it is used to evaluate diabetes. The World Health Organization estimates that 347 million people suffer from this disease worldwide. High levels of uric acid are related to conditions such as gout,  Lesch-Nyan disease, obesity, diabetes, hypertension and renal dysfunction. Cholesterol can aggravate medical conditions through its toxic derivatives or by depositing in arteries leading to plaque formation (atherosclerosis). Literature review spans from importance of those three compounds, their methods of quantifications, later passing to enzyme immobilization methods and as some of the proposed devices work in flow conditions a short description of laws governing flow in the paper matrix is also included. This chapter contains detailed descriptions of systems with both colorimetric and electrochemical detection including architectures such as spot test, lateral flow assay and a tangential flow device. A thorough study of enzyme immobilization methods on paper is also presented.