Biomedical Engineering Reference
In-Depth Information
trations, respectively. A comparison of Fig. 7.6a to Fig. 7.6c reveals that in-
creasing the sample target concentration speeds up the surface reaction in
all of the configurations. At all sample concentrations, the static biochannel
device exhibits the slowest hybridization rates. This result is expected for two
reasons. First, the transport of sample targets to the probes is controlled by
diffusion. Second, and more importantly, the channel configuration limits the
amount of targets that are easily accessible to each of the probe sites. The
bulk reactor, which is also a diffusion-dominated device, shows a better per-
formance, while the device with the oscillating sample provides for the best
hybridization performance. This result is as expected, since convection pro-
vides a faster means of transporting the targets to the surface. One of the
findings from these simulations is that at the highest concentrations, the bulk
reactor hybridization rates approach those for the oscillating biochannel de-
vice. This indicates that at higher target concentrations, the overall rates of
hybridization may be governed more by chemical kinetics at the surface than
by the e
ciency of transport of target species to the surface.
Fig. 7.6.
Time-variation of the surface-bound target for three different types of
hybridization reactors,
(a)
at 10 nMol target concentration,
(b)
at 1 nMol target
concentration,
(c)
at 0.1 nMol target concentration
