基于双链DNA-银纳米簇/金纳米棒构建荧光适体探针用于微囊藻毒素-LR传感分析OA

A fluorescent aptamer probe for highly sensitive sensing detection of microcystin-LR(MC-LR)was developed based on double-stranded DNA-silver nanoclusters(dsDNA-AgNCs)coupled with gold nanorods(AuNRs).Three DNA nucleotides were designed in this work,including one MC-LR aptamer chain and two C-riched single stranded DNA S1 and S2 complementary to aptamer.Single stranded DNA-AgNCs(ssDNA-AgNCs)with red fluorescence were synthesized by using single stranded DNA S1 and S2 as templates and reduction of silver ions(Ag+)with sodium borohydride(NaBH4).Two ssDNA-AgNCs hybridized with aptamer strands at its two ends to form negatively charged dsDNA-AgNCs with a maximum fluorescence emission at 624 nm.In the presence of positively charged AuNRs,fluorescent resonance energy transfer(FRET)occurred between dsDNA-AgNCs and AuNRs due to the electrostatic interaction,resulting in fluorescent quenching of dsDNA-AgNCs.After addition of the target MC-LR,MC-LR specifically bonded with aptamer of dsDNA-AgNCs,resulting in dissociation of dsDNA-AgNCs to ssDNA-AgNCs and restoring of fluorescence intensity.An"off-on"fluorescent aptamer probe was constructed for MC-LR quantitative detection.The proposed method exhibited a linear response for MC-LR detection in the concentration range of 5 ng/L to 500 μg/L with a detection limit of 1.7 ng/L.The proposed fluorescent aptamer probe possesses the advantages of simple preparation and high selectivity and sensitivity,and can be applied for the MC-LR detection in actual water samples.