Semiconductor Nanocrystal Probes for Human Metaphase Chromosomes
Yan Xiao, Peter E. Barker
Novel inorganic fluorophores called semiconductor nanocrystals have recently been incorporated into protein, antibody and microbead oligonucleotide detection methods where previously, organic dyes were universally employed. To improve quantitation of fluorescence in situ hybridization (FISH) for metaphase chromosome-level changes in medicine, DNA FISH probes detected with organic fluorophores and (CdSe) ZnS semiconductor nanocrystals were compared. Intensity and photostability of (CdSe) ZnSquantum dots in DNA FISH experiments show that quantum dot FISh probes were 11 times brighter than FITC probes and twice as bright at Texas Red probes. At two hours exposure in a FISH study, (CdSe) ZnS FISH probes retained 70% of hybridization signal intensity, exceeding signals detected by similarly photobleached Texas Red (27%) or FITC (11%). These results demonstrate the feasibility of quantum dot-labeled FISH probes for human metaphase chromosomes and enable more precise quantitation than organic labels for medical cytogenetics.