Cell-Based Fluorescence In Situ Hybridization Using Semiconductor Nanocrystal Probes in a Microfluidic Channel

The technique known as fluorescence in situ hybridization (FISH) is routinely used in gene research and clinical applications. Fluorophore-labeled DNA probes with a specific and complementary sequence is allowed to intercalate into a gene of interest for detection and/or quantitation. Typically used organic labels, such as Texas Red or fluorescein, are prone to bleaching when utilized for FISH experiments. Recently, the compatibility of semiconductor nanocrystals, or quantum dots, with biological systems has been greatly improved. Quantum dot labeling of DNA hybridized probes offers a brighter, more stable fluorescence-label for gene research when compared to often-employed organic fluorophores.

In addition to enhancement by use of quantum dots as FISH labels, the speed of this type of analysis can be improved by utilization of microfluidic techniques. Microchannels were cast into a silicone elastomer, and then placed over a glass slide to which cells were affixed and hybridized with biotinylated DNA probes. Streptavidin conjugated quantum dots were then flowed through the microchannel. The incubation time for the labeling with the quantum dots was cut from 30 min to 5 min when performed in the confinement of a microchannel. The variation in quantum dot signal due to change in pH is compared between the traditional FISH method, FISH performed with laser scanning cytometry, and microfluidic FISH.

Figure 1. Image of total DNA within cells by utilizing FISH with quantum dot fluorophores performed in a microfluidic channel

Author Information:

J. Christopher Ball       

Mentor – Laurie Locascio

Analytical Chemistry Division

Chemical Science and Technology Laboratory

Bldg 227 A361

MS-8394

Phone 975-4130

Fax 977-0587

chris.ball@nist.gov

Sigma Xi member- NO

Poster Category: Chemistry