Aptameric detection of quinine in reclaimed wastewater using a personal glucose meter

Abstract

Quantification of small-molecule analytes in an aqueous environment remains expensive due to the high costs of instruments and human resources. An aptamer–invertase biosensor coupled with a personal glucose meter (PGM) is a precise and promising method to substitute the traditional instruments. Herein, using quinine as an example, we demonstrated the feasibility of using an aptamer–invertase biosensor to quantify quinine in reclaimed wastewater. The analytical procedure consisted of building the structure of aptamer–DNA–invertase on magnetic beads, competition between quinine and invertase, catalysis of sucrose by the released invertase, and quantification of glucose by a PGM. The dissociation coefficient of aptamer and quinine was estimated to be 0.36 μM by isothermal titration calorimetry, indicating very strong affinity between them. The linear calibration curve of quinine was in the range from 0 to 2 μM. The limit of detection (LOD) was estimated to be 0.13 μM for quinine in pure water and 0.32 μM for quinine in reclaimed wastewater. The selectivity for quinine detection in the presence of other pharmaceutics was satisfactory. Thus, the aptamer–invertase–PGM method is an inexpensive, affordable and feasible choice for quinine analysis in wastewater management.