Enantioanalysis of Serine Using Stochastic Enantioselective Sensors

Enantioanalysis of serine can act as a key factor for metabolomics of colon cancer. Therefore, two stochastic enantioselective sensors based on nanographene and copper oxide modified with calix[6]arene and calix[4]arene-25,26,27,28-tetrol have been designed, characterised and validated. High sensitivities, selectivities, and enantioselectivities were recorded for the enantioanalysis of serine at two pH values 7.40 and 3.00. At pH 7.40, for the L-serine the wider linear concentration range (1 × 10 −17 − 1 × 10 −2 mol l −1 ) was obtained using the sensor based on calix[4]arene-25,26,27,28-tetrol, while the best sensitivity (1.31 × 10 9 s −1 mol l −1 ) was given by the sensor based on calix[6]arene; for the assay of D-serine at the same pH the wider linear concentration range (1 × 10 −18 − 1 × 10 −2 mol l −1 ) and the higher sensitivity (3.78 × 10 11 s −1 mol l −1 ) were obtained using the calix[4]arene-25,26,27,28-tetrol based sensor. At pH 3.00, for the assay of L-serine, the best sensitivity (3.75 × 10 7 s −1 mol l −1 ) was obtained using the sensor based on calix[4]arene-25,26,27,28-tetrol, while the wider linear concentration range (1 × 10 −16 − 1 × 10 −6 mol l −1 ) was obtained using the sensor based on calix[6]arene; a wider linear concentration range for the assay of D-serine (1 × 10 −18 − 1 × 10 −4 mol l −1 ) was given by the sensor based on calix[4]arene-25,26,27,28-tetrol, while for the same enantiomer the highest sensitivity (2.08 × 10 8 s −1 mol l −1 ) at this pH was obtained using the sensor based on calix[6]arene. The enantiomers of serine were able to be determined up to 1 × 10 −18 mol l −1 with high recoveries, and low relative standard deviations.