Microcystin-LR (MC-LR) is a cyclic heptapeptide with hepatotoxic and neurotoxic activities in mammals, which is the most widespread variant of MCs produced by cyanobacterial in eutrophic water. Here, an effective adsorbent using aptamer modified graphene oxide (GO) was designed to detect MC-LR at low concentrations. GO was functionalized with an MC-LR aptamer (Apt-3) by surface modification using polyethylene glycol (PEG). Then, the novel aptamer-conjugated GO (Apt-3/PEG/GO) was used to enrich and separate MC-LR from pond water or freshwater snail samples following by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) analysis. Results indicated that the Apt-3/PEG/GO nanocomposites were highly specific to MC-LR, and the detection limit of MALDI-MS was 0.50 ng/mL in spiked, environmental water samples. Moreover, the MC-LR can be released from nanocomposites by heating, thus the reuse of Apt-3/PEG/GO is realized. Real samples analysis indicated that the Apt-3/PEG/GO nanocomposites coupled with MALDI-MS was efficient in detection trace amount of MC-LR in snail samples. With the merits of low cost, reusable, easy to synthesis and to flexible assembly, the Apt-3/PEG/GO nanocomposites is a novel adsorbent with extensive applications, and its combination with MALDI-MS is expected to assess other analytes by anchoring suitable aptamers for different targets.
