Cyclodextrin-based micro neurotransmitter sensor for selective catecholamine hormone detection

This paper reports the fabrication and testing results of the first, within our knowledge, micro neurotransmitter sensor that enables selective detection of catecholamine hormones based on a differently-chemically-modified electrode array with respective cyclodextrin `catchers.´ Derangement within a sequence of catecholamine hormones through neuronal terminals is well known for causing human neuronal diseases. However, the accurate, real-time, and relative identification of catecholamine hormones (i.e. dopamine, L-dopa, and L-tyrosine) has been much limited because the affinities of catecholamine hormones are too similar to be distinguished by conventional enzyme-based chemical sensing methods. To address such limitations, we have employed cyclodextrin (CD) `catchers´ that physically engage differently-sized hormone molecules with high selectivity. The fabricated neurotransmitter sensor successfully identified individual hormones with respective CD `catchers´: α-CDs responded best to L-tyrosine producing 10% higher signature signal compared to others; γ-CDs to L-dopa by 45%; and β-CDs to dopamine by 47%, respectively. For example, the sensitivity of β-CDs detecting Dopamine (8.27×10^-9A/M, A: ampere, M: mole) was higher than two other electrodes (7.96×10^-9 and 7.54×10^-9 A/M for α-CDs and γ-CDs, respectively).