2D Enantioselective Disposable Stochastic Sensor for Fast Real-Time Enantioanalysis of Glutamine in Biological Samples

Abstract

As protein is both a structural component and a metabolic intermediary, amino acids play a crucial function in the body. When it comes to proteins, only the L-configuration of chiral amino acids is found. At the molecular level, symmetry is disrupted; however, the scientific basis for this symmetry breaking is not yet known. Enantioanalysis of chiral compounds such as amino acids plays a very important role in the correct diagnosis of illnesses, such as cancer. The enantiomers of glutamine—a chiral amino acid—were investigated in biological samples using a disposable stochastic sensor. The disposable stochastic sensor based on immobilization of maltodextrin (DE 4.0–7.0) on the surface of a disposable sensor based on graphene decorated with Ag was designed, characterized, and validated for screening tests of whole blood and tissue samples. The stochastic sensor was designed using cold plasma deposition of graphene decorated with Ag on plastic material. The sensor was enantioselective, being able to discriminate between the enantiomers of glutamine. High sensitivities were recorded for both enantiomers, while the limits of determination were 100 fmol L−1 for L-glutamine and 1 fmol L−1 for D-glutamine. High recoveries were determined for the assay of one enantiomer in the presence of the other, despite the ratio between the two enantiomers.