Aptamer-antibody chimera sensors for sensitive, rapid and reversible molecular detection in complex samples

Abstract

The development of receptors suitable for the continuous detection of analytes in complex, interferent-rich samples remains challenging. Antibodies are highly sensitive but difficult to engineer in order to introduce signaling functionality, while aptamer switches are easy to construct but often yield only modest target sensitivity. We present here the programmable antibody and DNA aptamer switch (PANDAS), which combines the best features of both systems by using a nucleic acid tether to link an analyte-specific antibody to an internal strand-displacement (ISD)-based aptamer switch that recognizes the same target. The monoclonal antibody mediates initial analyte binding due to its higher affinity; the resulting increase in local analyte concentration then leads to cooperative binding and signaling by the ISD switch. We developed a PANDAS sensor for the clotting protein thrombin and show that this design achieves 100-fold enhanced sensitivity compared to using an aptamer alone. This design also exhibits reversible binding, enabling repeated measurements with temporal resolution of [~]10 minutes, and retains excellent sensitivity even in interferent-rich samples. With future development, this PANDAS approach could enable the adaptation of existing protein-binding aptamers with modest affinity into sensors that deliver excellent sensitivity and minute-scale resolution in minimally prepared biological specimens.