Precisely Encoded Barcodes Using Tetrapod CdSe/CdS Quantum Dots with a Large Stokes Shift for Multiplexed Detection

A serious obstacle to the construction of high-capacity optical barcodes in suspension array technology is energy transfer, which can prompt unpredictable barcode signals, limited barcode numbers, and the need for an unfeasible number of experimental iterations. This work reports an effective and simple way to eliminate energy transfer in multicolor quantum dots (QDs)-encoded microbeads by incorporating tetrapod CdSe/CdS QDs with a large Stokes shift (about 180 nm). Exploiting this unique feature enables the facile realization of a theoretical 7 x 7-1 barcoding matrix combining two colors and seven intensity levels. As such, microbeads containing tetrapod CdSe/CdS QDs are demonstrated to possess a powerful encoding capacity which allows for precise barcode design. The ability of the Shirasu porous glass membrane emulsification method to easily control microbead size facilitates the establishment of a 3D barcode library of 144 distinguishable barcodes, indicating the enormous potential to enable large-scale multiplexed detection. Moreover, when applied for the multiplexed detection of five common allergens, these barcodes exhibit superior detection performance (limit of detection: 0.01-0.02 IU mL(-1)) for both spiked and patient serum samples. Therefore, this new coding strategy helps to expand barcoding capacity while simultaneously reducing the technical and economic barriers to the optical encoding of microbeads for high-throughput multiplexed detection.