Molecularly imprinted polymers (MIPs) have been widely used for the modification of electrodes because of their native specificity for the intrinsic template molecules. The importance of catecholamines in the neurological and general well-being of every individual cannot be overemphasized. Disorders associated with the imbalance in catecholamine levels can be diagnosed with electrochemical sensors capable of their determination in the presence of other biological interferents in extracellular fluids. MIPs based sensors have been designed for selective and simultaneous determination of these catecholamines in the past decade. Efforts in this regard and details on the components and preparation of these MIPs were presented in this review.

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The current study compared the synthesis, characterization and properties of copper oxide nanoparticles (CuO) based on green and traditional chemical methods. The synthesized CuO were confirmed by spectroscopic and morphological characterization such as ultraviolet-visible (UV-vis) spectroscopy, fourier transform infrared (FTIR) spectroscopy, zeta potential, scanning electron microscopy (SEM) and energy dispersed X-ray (EDX). Electrochemical behavior of the modified electrodes was done using cyclic voltammetry (CV) in ferricyanide/ferrocyanide ([Fe(CN)6]4−/[Fe(CN)6]3−) redox probe. As revealed by UV spectrophotometer, the absorption peaks ranged from 290–293 nm for all synthesized nanoparticles. Based on SEM images, CuO were spherical in shape with agglomerated particles. Zeta potential revealed that the green CuO have more negative surface charge than the chemically synthesized CuO. The potential of the green synthesized nanoparticles was higher relative to the chemically synthesized one. Cyclic voltammetry studies indicated that the traditional chemically synthesized CuO and the green CuO have electrocatalytic activity towards the ferricyanide redox probe. This suggests that the green CuO can be modified with other nanomaterials for the preparation of electrochemical sensors towards analytes of interest.

Imbalance in the levels of monoamine neurotransmitters have manifested in severe health issues. Electrochemical sensors have been designed for their determination, with good sensitivity recorded. Carbon-based quantum dots have proven to be an important component of electrochemical sensors due to their high conductivity, low cytotoxicity and opto-electronic properties. The quest for more sensitive electrodes with cheaper materials led to the development of electrochemical sensors based on carbon-based quantum dots for the detection of neurotransmitters. The importance of monoamine neurotransmitters (NTs) and the good electrocatalytic activity of carbon and graphene quantum dots (CQDs and GQDs) make the review of the efforts made in the design of such sensors for monoamine NTs of huge necessity. The differences and the similarities between these two quantum dots are highlighted prior to a discussion of their application in electrochemical sensors over the last ten years. Compared to other monoamine NTs, dopamine (DA) was the most studied with GQDs and CQD-based electrochemical sensors.