









 |
In collaboration with
Prof. Karsten Haupt,
UTC, France
Belmont, Sokuler,
Haupt, Gheber, "Direct writing of molecularly imprinted
microstructures using a nanofountain pen", Appl. Phys.Lett.
90, 193101 (2007)
Kantarovich,Belmont,Haupt,Bar, Gheber, "Detection of template
binding to molecularly imprinted polymers by Raman
microspectroscopy",Appl. Phys.Lett. 94, 194103 (2009)
Kantarovich, Tsarfati, Gheber, Haupt, Bar "Writing
Droplets of Molecularly Imprinted Polymers by Nano Fountain
Pen and Detecting Their Molecular Interactions by
Surface-Enhanced Raman Scattering", Anal. Chem.
81, 5686–5690 (2009)
|
|
The technique
of molecular imprinting allows for the preparation of synthetic
polymers with specific binding sites for a target molecule. This
can be achieved if the target is present during the
polymerization process, thus acting as a molecular template.
Monomers carrying certain functional groups are arranged around
the template through either noncovalent or covalent
interactions. Following polymerization with a high degree of
cross-linking, the functional groups become fixed in defined
positions by the polymer network. Subsequent removal of the
template by solvent extraction or chemical cleavage leaves
cavities that are complementary to the template in terms of
size, shape and arrangement of the functional groups. These
highly specific receptor sites are capable of rebinding the
target molecule with high specificity, sometimes comparable to
that of antibodies. Molecularly imprinted polymers have
therefore been named "antibody mimics". It has been shown that
they can be substituted for biological receptors in certain
formats of immunoassays and biosensors.
In an attempt
to use this technique to realize nano-arrays of molecularly
imprinted polymers (MIPs), we deposit the pre-polymerization
mixture using
NFP,
and subsequently (UV) polymerize the resulting nanostructures,
much like in our work on microlenses. |

When the template is a fluorescent molecule
(fluorescein, in this case), the array and other written
features are directly observable with a fluorescence microscope. |

An example of less than 100 nm thick dots of MIPs |
A fluorescent template molecule
enables us to directly observe binding and releasing of the
analyte, by observation of the fluorescence intensity, in a flow
cell mounted on the stage of the fluorescence microscope.

|

Single dots of different compositions. The one in
a and the zoom in showed in b is more porous (thus
the cavities are more accessible to the analyte) than the one in
c and (zoomed image in) d. |

Unbinding and rebinding
experiment, including control (non-imprinted) dots. The four
small dots, surrounding the large central one, are
non-imprinted. The different size is intentional, to enable easy
distinguishing of the imprinted and non-imprinted dots. It is
obvious that the imprinted dot binds (and releases) fluorescein,
while the four non-imprinted ones do not bind it. |
|
|