Ultrasensitive Electrochemical Sensor for Catecholamine Detection Using Stable Covalent pH Sensitive Thin Films

Abstract

Electrochemical detection of catecholamine neurotransmitters has been widely studied and possess lots of potential for the onsite analysis. Electrochemical sensors, however, have limitations that are due to strong interfering species that exist in the same sample matrix as the analyte of interest. In addition, the stability of the fabricated electrochemical sensor is important for reusability and reproducibility. Our research group activities have focused on fabricating stable thin films of electrocatalysts (phthalocyanines) and their graphene conjugates using covalent coupling reactions and electrografting method. The formed thin films exhibited excellent stability, electroanalytical and electrocatalytic properties. The flexible structural modification of phthalocyanines allowed for the incorporation of pH sensitive functional group and different metal ions for electrocatalysis. The use of pH sensitive electrocatalysts is a step away from using insulating and negatively charged polymers for screening interferents. The evaluation of modified electrodes were conducted in the negative and positively charged redox systems, such as [Fe(CN)6]3-/4- and [Ru(NH3)6]2+/3+. Excellent electrocatalytic properties were obtained and the electrodes could detect the neurotransmitters selectively and screen-off ascorbic acid, uric acid using the solution pH.