Quantum dot-tagged microspheres for fluid-based DNA microarrays

Quantum dot‐embedded microspheres offer a promising technology for the development of a fluid‐based DNA microarray to replace current biochip microarray technology. The narrow emission and long lifetime from the quantum dots (QD's) is ideal for dense spectral multiplexing. Also, the QD's may all be excited by a single source. To implement this solution, we have fabricated CdSe quantum dots following published procedures and embedded them in polystyrene microspheres. As a first step in this development, we have investigated the use of a flow cytometer in analyzing the encoded microspheres. We demonstrate the use of a microsphere‐based DNA detection system and investigate the readout of quantum dot‐tagged microspheres. We also discuss some of the inherent limitations and difficulties of using such a system to address the need for a high‐throughput readout for spectral multiplexing for fluid‐based DNA microarrays.