CARBON FIBER MICRO ELECTRODES AS AMINO ACID SENSORS USING FAST SCAN SYCLIC VOLTAMMETRY

During the past few decades, carbon fiber microelectrodes (CFMEs) have been used for the detection of biomolecules. This method has developed the electrochemical field for improving analytical techniques. Amino acids always have a critical role since they are the monomer backbone of the peptides, therefore, it is necessary to develop a rapid technique for measuring them. Peptides are vital and essential for the human body as they perform physiological and metabolic functions. Most of the Amino acids make up the main components of neurotransmitters, which are one of the important classes of biomolecules, and studying them is valuable for determining several diseases and administering pharmacological treatments. Therefore, studying amino acids as the building blocks of peptides has garnered much research interest. Along with using electrochemical biosensors, fast-scan cyclic voltammetry (FSCV), which is an electrochemical method that provides good temporal resolution, is used by scientists for biomolecule detection. CFMEs are suitable for amino acid and peptide detections due to their unique advantages such as their small diameter, which allows them to measure molecules in vivo without much tissue damage. Moreover, they can rapidly measure compounds when used with FSCV. In this method, Tyrosine was detected when applying the Triangle Waveform, when scanned from the holding potential -0.2V to the switching potential of +1.2V and back. This waveform was insufficient and was not able to solely measure tyrosine due to the shift in the CV plot which was attributed to the pH shift caused by the acidic pH of the stock solution. Using the measured current, the chemical properties of the substance can be determined as the shape and position of the voltammogram are a fingerprint for chemical detection and the peak oxidative current is proportional to concentration. Therefore, the Modified Waveform, with a holding potential of -0.2V to the transition potential of +0.7V and switching potential of +1.2V, with two different scan rates applied the huge oxidation shift eliminated. When co-detecting the Tyrosine(Tyr) with dopamine (DA) and norepinephrine (NE) simultaneously by (1-1-10) ratios of concentration it’s observed that DA and NE share an oxidation peak, therefore a singular peak was seen around +0.6 V and the peak for Tyr was observed at approximately +1.1 V.