▎ 摘　　要

A broad-spectrum ssDNA aptamer containing 80 nucleotides (LA80) and capable of binding to four different sources of lipopolysaccharides (LPSs) was truncated. Two strategies are used to produce truncated aptamers of different length. The results show that LA27, a 27-nt aptamer, retained broad-spectrum capability and has a higher affinity (K-d=46.29.5nM). A graphene oxide based fluorescence polarization assay (excitation/emission wavelengths: 485/520nm) was worked out using FAM-labeled LA27. It can detect LPSs from Salmonella entericaserotype typhimurium, Pseudomonas aeruginosa 10 and Escherichia coli 055:B5 with enhanced performance (4.8 to 29-fold improvements) compared to LA80. The assay can be performed within 30min, and the detection limits are 38.7, 88.0 and 154ng center dot m-1, respectively.