Simultaneous determination of zeatin and systemin by coupling graphene oxide-protected aptamers with catalytic recycling of DNase I

• We have demonstrated the first use of the signal amplified aptasensor for simultaneous detection of zeatin and systemin.
• This sensitivity is about two orders of magnitude higher than that of traditional fluorometric methods without amplification.
• There is no cross-reaction between zeatin and systemin.
• This sensor could be used to detect zeatin and systemin in plant tissue culture.

Plant hormones are a collection of small molecules which play important roles in regulating the growth and development processes of plants. In this work, a sensitive and novel sensing platform for simultaneous multiplex detection of plant hormones is presented with choosing systemin and zeatin as the model targets. In the absence of the targets, the dye-labeled aptamers were adsorbed on the surface of graphene oxide (GO), result in the fluorescences of the dyes intensively quenched by GO which could also protect the aptamers from nuclease cleavage. While in the presence of the targets, the aptamers could be detached from the GO surface by specifically binding with targets. The fluorescences of the dyes were synchronously recovered and could be further amplified by DNase I catalytic recycling of self-produced reactants. So the two plant hormones can be simultaneously quantitatively determined by using synchronous scanning fluorescence spectrometry with no cross reaction between the two probes. The experimental results reveal that fluorescence intensities of two dyes exhibit good linear dependence on their target concentrations in the range of 0.67–6.0 μM and 0.33–5.0 μM with the detection limit of 60 nM and 35 nM for zeatin and systemin, respectively.