Synthesis of water-soluble Ag2Se QDs as a novel resonance Rayleigh scattering sensor for highly sensitive and selective ConA detection

Abstract

Ag₂Se quantum dots (QDs) have attracted a lot of interest due to their potential applications in biosensing and bioimaging. A strategy is presented that involves coupling of selenium powder reduction with the binding of silver ions, and thioglycollic acid (TGA) and glycine as stabilizers to obtain ultrasmall Ag₂Se QDs at 85 °C in aqueous solution. This strategy avoids high temperatures, high pressures and organic solvents so that water-soluble 3 nm Ag₂Se QDs can be directly obtained. The conjugation of ConA to TGA stabilized Ag₂Se QDs by hydrogen bonds leads to the adsorption of ConA to Ag₂Se QDs and forms the aggregation and leads to the generation of resonance Rayleigh scattering (RRS) as a readout signal for the sensing events. The reaction mechanism of Ag₂Se QD RRS enhancement is studied in this work. The resulting RRS sensor enables the detection of ConA with limit of detection reaching 0.08 μg mL⁻¹ concentration in a wide linear range from 0.27 μg mL⁻¹ to 35 μg mL⁻¹. The recovery of spiked ConA in human serum samples ranges from 94% to 106%. The relative standard deviation (RSD) for eleven replicate detections is 3.6%. Our results correlate many important experimental observations and will fuel the further growth of this field.