Graphene oxide-gated mesoporous silica nanocontainers using aptamers for arsenite detection with glucometer readout

A newly portable detection sensing platform based on a graphene oxide (GO)-gated mesoporous silica nanocontainer (MSN) was designed for arsenite detection through the target-responsive release of glucose from the MSN with a glucometer readout. To construct such a biosensing system, the arsenite aptamer was initially conjugated covalently onto the mesoporous silica nanoparticles through the epoxy-amino reaction. Thereafter, the indicators (glucose molecules) were gated into the pores by using graphene oxide nanosheets, on the basis of π-stacking interactions between the nucleobases and graphene. Upon target arsenite introduction, graphene oxide was displaced from the MSN thanks to a specific reaction between the analyte and the aptamer, thus resulting in the opening of the pores to release the loaded glucose molecules, which could be determined quantitatively by using a portable personal glucometer (PGM). Based on the different affinities between graphene and the analyte for the labeled aptamer on the MSN, the amount of released glucose molecules from the pores increased with the increasing arsentite concentrations. Under optimal conditions, the GO-gated aptasensing system exhibited good PGM responses relative to arsenite concentrations within the dynamic working range of 0.01-100 ng mL^-1 (ppb) at a detection limit of 2.3 pg mL^-1 (ppt). The coefficients of variation (CVs) for the reproducibility of intra-assay and inter-assay were below 9.1% and 11.6%, respectively. In addition, the methodology also displayed high specificity and selectivity towards target arsenite against other ions, and was applicable for monitoring arsenite in water samples, giving well-matched results in accordance with the referenced ICP-MS.