Loss of cognitive functions represents one of the most significant challenges that modern society faces in improving the quality of life for the elderly. Advances in understanding the morphological and functional changes in neuronal networks associated with both normal and pathological brain aging have rapidly progressed in recent years. Early accurate diagnosis, along with accessible and straightforward methods, is essential for timely treatment. Amino acids (AA) play vital roles in most biological processes and apart from glycine, they all exhibit a chiral center giving rise to two enantiomeric forms, the L- and D-enantiomers. Historically, D-amino acids (D-AA) were considered ‘unnatural’, and believed to exist only in microorganisms and invertebrates. However, recent findings have identified D-AA in biological fluids and tissues, particularly within the nervous system and sensory systems. This proposal aims to develop a practical methodology to assess the effectiveness of newly synthesized probes in determining the D-/L-AA ratio in biological matrices, with the goal of enabling an early diagnosis of condition related with dementia, namely, Alzheimer’s disease.