Optical Biosensors & Biophotonics

Quantum dot switches for biomolecular sensing

Semiconductor quantum dots, such as ZnS-capped CdSe nanocrystals, are extremely attractive fluorescent probes for biosensing applications possessing: very high fluorescence yields, extinction coefficients several times higher than convention organic fluorophores, low photobleaching, but most importantly narrow, symmetric emission peaks (approx 25-35nm, full width at half maximum) which can be tuned as a function of the particle size. We have recently demonstrated that the emission of CdSe quantum dots linked to the 5’-end of a DNA sequence is efficiently quenched by hybridisation with a complementary DNA strand with a gold nanoparticle attached at the 3’-end; contact of the quantum dot and gold nanoparticle occurs.

Present activities include exploitation of the patterned surfaces for

1. Biomolecular sensing of low copy numbers of DNA in integrated devices, (in collaboration with Prof. Tom Brown from Chemistry)
2. Self-assembly strategies for nanophotonic/electronic devices (in collaboration with Prof. Jeremy Baumberg from Physics)