Jahresbericht 2005 - IPHT Jena

B. DNA-chip Technology
Characterization of specific metal deposition
at single particle level
(G. Festag, W. Fritzsche)
Specific reductive deposition of silver on gold
nanoparticles has a tremendous importance for
numerous processes in molecular construction
as well as in various kinds of bioanalytical methods
for signal enhancement. AFM was used to
study this process at the single particle level in
order to reveal the influence of parameters like
particle size, composition of enhancement solution,
length of incubation etc. Because on-line
measurements were not feasible, techniques
were developed to relocate certain positions at
the sample in order to image particle arrangements
after every enhancement step.
Fig. 3.10: AFM study of the growth of a silver
shell on gold nanoparticles at the single particle
level. Top: Three images of the same sample
position after different growth times; Bottom:
Dependence of particle height on growth time
and various start diameters.
Electrical identification of microorganisms
by DNA-chip technology
(T. Schüler, R. Möller, W. Fritzsche)
The electrical DNA-detection system that has
been developed at the IPHT was for the first time
applied to biological samples (PCR fragments).
In collaboration with the Leibniz Institute for Natural
Product Research and Infection Biology –
Hans-Knöll-Institute (HKI) Jena, the electrical
DNA detection was utilized to identify species
of microorganisms. Therefore, capture DNA
sequences, specific for each of the studied
species, were immobilized into the electrode
gaps prior to incubation with the target DNA.
MIKROSYSTEME / MICROSYSTEMS
Target DNA binding is detected by a significantly
reduced resistance in the respective gap
because binding of the labeled target DNA will
lead to metal deposition in a subsequent signal
enhancement step. The results showed that the
electrical DNA chip detection is able to clearly
differentiate between the different species and
allows for a straightforward identification of
microorganisms.
Fig. 3.11: Measurements from a typical experiment
with the electrical DNA-chip system show a
clear signal for the species K. setea (set, left column)
and the positive control from a consensus
sequence (uni). An optical view on an electrical
chip visualizes the silver deposition (especially in
the 1+2 row and the last one) that leads to the
electrically detectable signal at these positions.
3.2.3 Micro system technology
(Th. Henkel)
Photonic instrumentation strongly depends on
the integration of micromechanical and microoptical
components with critical dimensions in the
nanometer scale. Furthermore, LabOnChip systems
for integrated sample placement and sample
preparation are required for high-throughput
microoptical applications, the retrieval of spatialand
time-resolved spectral information and localized
photochemical activation of sample ingredients.
The aim of the microsystem technologies
department is the development and fabrication of
components for photonic instrumentation and the
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