Determination of free tryptophan in serum with aptamer-Comparison of two aptasensors

Two aptasensors based on graphene oxide (GO) and molecular beacon were designed for the detection of L-tryptophan (L-Trp) using L-Trp aptamer (Trp3a-1). A quantitative assay of L-Trp over the concentration range of 10-500 μM and with a detection limit of 6.84 μM were achieved by GO-based aptasensor. For molecular beacon based aptasensor, FRET between Trp3a-1 labeled with FAM and an oligonucleotide (CS-Trp3a-1, labeled with BHQ-1) which is partially complementary with the aptamer was used to detect L-Trp. With a linear relationship in 10-500 μM and a detection limit of 6.97 μM in 25% serum, the aptasensor is expected to be improved for the detection of free L-Trp in other complex samples.190