Novel potentiometric biosensor for amino acids detection

Identifier:  TFM:298

Handle: https://hdl.handle.net/20.500.11797/TFM298

Authors:  Spasojević, Irena

Abstract:
The development of a novel paper-based enzymatic sensor for potentiometric detection of amino acids is presented. The sensor consists of a platinized paper that acts as a redox-sensitive substrate and a layer of Nafion on top of which the enzyme L-Amino Acid Oxidase (LAAO) is immobilized into Chitosan polymeric matrix. Nafion acts as perm-selective barrier, avoiding the transport of negatively charged species while being permeable to neutral species such as H2O2. The composition of the biosensor was optimized and the response to different amino acids with different side chains was explored. Nonpolar amino acids with aromatic groups (Phe, Tyr and Trp) reported the highest sensitivity (-32.3, -56.1 and -45.3 mV/decade respectively) within the 10-4 to 10-3 M linear range, i.e., the normal clinical range of amino acids present in human plasma. All other screened amino acids display almost negligible response. The only exception is Cys, which shows response due to its own redox characteristics. Thus, since the concentration of Cys may be independently determined, the herein developed sensor could find possible application for the detection of total aromatic amino acid content.