A robust covalent coupling scheme for the development of FRET aptasensor based on amino-silane modified graphene oxide

摘要： In recent years, numerous aptamers have been physisorbed on graphene oxide (GO) to develop FRET based aptasensors based on the high fluorescence quenching efficiency of GO. However, physisorbed aptasensors show poor signal reversibility and reproducibility as well as nonspecific probe displacement and thereby, are not suitable for many analytical applications. To overcome these problems when working with complex biological samples, we developed a facile and robust covalent surface functionalization technique for GO-based fluorescent aptasensors using a well studied adenosine triphosphate (ATP) binding aptamer (ABA). In the scheme, GO is first modified with amino-silane, and further with glutaraldehyde to create available carbonyl groups for the covalent attachment of a fluorophore and an amino dual modified ABA. The surface modification method was characterized by zeta potential, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The linearity, sensitivity, selectivity and reversibility of the resulting GO based covalent aptasensor was determined and systematically compared with the physisorbed aptasensor. While both sensors showed similar performance in terms of sensitivity and linearity, better selectivity and higher resistance to nonspecific probe displacement was achieved with the developed covalent ABA sensor. The surface modification technique developed here is independent from the aptamer sequence and therefore could be used universally for different analytical applications simply by changing the aptamer sequence for the target biomolecule.