Peptide aptamer-based colorimetric sensor for the detection of L-tryptophan in porcine serum

L-Tryptophan (L-Trp), one of the essential amino acids, is crucial for human physiological homeostasis and a limiting amino acid in animal feed. In addition, L-Trp is a precursor of some important biomolecules in the body, such as pentraxin and melatonin. Disorders of L-Trp metabolism in the body may cause Alzheimer's or Parkinson's disease. Therefore, monitoring L-Trp levels in the body fluids quickly and accurately is essential. A colorimetric biosensor was developed for the rapid detection of L-Trp in solutions by coupling a novel, screened, and validated peptide aptamer with Au nanoparticles via the Au-S bond. The biosensor showed a wide linear detection range of 1 µM − 1000 µM, and in addition, it was simple to construct, and the reaction time was as short as 10 s. In the analysis of L-Trp in actual porcine serum samples, the relative standard deviations were 4.52 % to 3.01 % compared with those of the high-performance liquid chromatography method, and the spiked recoveries were 99.2 % to 100.2 %. This new type of recognition probe is likely to gain attention in the field of bioanalysis owing to its biocompatibility, ease of modification, and easy linkage to nanomaterials.