Graphene Oxide-Based Homogeneous Fluorescence Sensor for Multiplex Determination of Various Targets by a Multifunctional Aptamer

A sensitive and selective fluorescent aptasensor for the determination of metal ions, small molecules, sequence-specific DNA, and proteins was fabricated. The analytical approach was based on target-induced conformational changes of the probe and the self-assembled probe-graphene oxide architecture. The probe employed fluorescence “on/off” switching in a single step in solution. This approach was simple to prepare and had little background with good sensitivity and rapid response. In the absence of targets, the probe adsorbed on the surface of graphene oxide through π–π stacking and quenched fluorescence of the probe. Upon the addition of analyte, the random coil of the probe bonded to the targets, reducing the interaction between the probe and graphene oxide, which disrupted the energy transfer from the probe to graphene oxide and therefore increased the fluorescence. This approach was employed for the determination of Ag⁺, Hg²⁺, cysteine, sequence-specific DNA, and thrombin. The results demonstrated that the probe-graphene oxide architecture was an excellent and versatile platform for the determination of multiple analytes.