Quantum dot nanobarcodes: epitaxial assembly of nanoparticle-polymer complexes in homogeneous solution.

Multiplexed nanobarcodes have been prepared with quantum dots (QDs) and alternating amphiphilic copolymers consisting of hydrocarbons and maleic anhydride groups. In homogeneous solution, the QD-polymer complexes grow epitaxially into nanobeads of narrow size dispersity, which has been previously achieved only for micrometer-sized beads in the presence of solid supports. As a result of this new nanostructure formation mechanism, more than 250 QDs can be loaded into a nanobead of 100 nm in diameter. A model assay for sensitive detection of human prostate specific antigen has also been demonstrated using the QD-nanobeads as fluorescent reporters. This nanoparticle-polymer self-assembly technology is capable of producing a variety of nanostructures and is expected to open new opportunities in nanoparticle-based ultrasensitive detection and imaging.