Enzymatically modified nanoparticle sensors for measuring choline and acetylcholine in food and biota (Part I: Carbon electrodes)

Choline, a vitamin-like compound, is an essential nutrient and plays vital roles in important metabolic pathways. It is important for brain development especially in cellular growth that occurs during fetal development. It also participates in acetylcholine synthesis and its abnormal amount is a sign of disease conditions. Nowadays choline and acetylcholine are added to certain foods and therefore their quantitative determination is very important in food industries and clinical analysis. Chromatographic methods are usually used but tedious sample preparation, long separation time, use of high sample and mobile phase volumes and an experienced operator, limited their applications. In this regard, application of bio-sensors as a green method with the benefits of high sensitivity and convenient application have been noted. The hydrogen proxide as the product of enzymatic reaction is measured with optical or electrochemical methods. In this review, published researches (from 2000 to present) in the field of application of nano-particles in the design of this biosensors and determination of choline and acetylcholine has been reviewed. Application of nano-materials cause more enzyme immobilization with better stability and bioactivity, improve the electron transfer and decrease the resistance, and as a result enhancement in the figure of merits of the method.