.jpg)
The development of microarrays for analysis and manipulation of cells or
viruses has attracted considerable interest from both researchers and biomedical
related industry. Different kinds of biological microarrays are under intense
investigation to facilitate early detection and analysis of biological events;
these are DNA microarrays, Protein microarrays, Tissue and Antibody gene chip
analysis, chemical compound arrays to name a few.
|
Microarray is a multiplex
lab-on-a-chip. It is a 2D array on a solid substrate (usually a glass slide or
silicon thin-film cell) that assays large amounts of biological material using
high-throughput screening methods.
DNA Microarray, also known as DNA chip, is a small solid
support, usually a membrane or glass slide, on which sequences of DNA are fixed
in an orderly arrangement. DNA microarrays are used for rapid surveys of the
expression of many genes simultaneously, as the sequences contained on a single
microarray can number in the thousands.
Protein Microarray, also known as a protein binding
microarray, provides a multiplex approach to identify protein-protein
interactions, to identify the substrates of protein kinases, to identify
transcription factor protein-activation, or to identify the targets of
biologically active small molecules.
Chemical Compound Microarray is a
collection of organic chemical compounds spotted on a solid surface, such as
glass and plastic. This microarray format is very similar to DNA microarray,
protein microarray and antibody microarray.
Antibody Microarray is a specific form of protein
microarrays, a collection of capture antibodies are spotted and fixed on a solid
surface, such as glass, plastic and silicon chip for the purpose of detecting
antigens.
Tissue Microarrays consist of
paraffin blocks in which up to 1000[1] separate tissue cores are assembled in
array fashion to allow multiplex histological
analysis. |
Within the MacDiarmid
Institute for Advanced Material and Nanotechnology, we are investigating the
use of nanoscale imaging technologies that might help in the fundamental
understanding of cell function and lead to early diagnosis of diseases at a
single cell and molecular level.
We have recently
developed a novel technique for replicating biological cellular and sub cellular
structures1-4. This method facilitates imaging
individual cells at high resolution and offers a snap shot record of cell
response to stimulus. Termed Bioimprint, it has enabled us to detect features of
fusion pores in cells at unprecedented resolution down to the nanometer scale
(nano-bio-imaging). Bioimprint integrates soft lithography directly with
biological materials to create replica cell impressions in a robust storage
medium to facilitate topographical analysis using Atomic Force Microscopy.
In combination with our BioChip platform5,6, which traps individual cells in its cavities, we are creating a very
powerful tool for single cell analysis. Single cell analysis is utilised to
provide unique understanding of important biological mechanisms as it enables us
to look at the response of individual cells to different stimulation
conditions.
In developing a protocol for the bioimprint/biochip processes a new polymer
has been especially prepared by our collaborators at the New Zealand Plant and
Food Research Centre for this work that showed promising results as it cures at
room temperature under UV exposure and we have achieved the imprinting of muscle cells with high
precision.
Using these techniques we were the first to show AFM images of cancer cells and
investigate the potential of imaging techniques for early detection and analysis
of cancer.
.jpg)
|
|
AFM images at two powers of magnification, in
which craters and pores are visible and AFM trace
scans. |
We have explored
nanoimaging of exocytotic pores on cell membranes through which a biological
cell transfers peptides to the outside of the cell. Some peptides can stimulate
cancer growth. Peptides are made in cells and packaged into granules within the
cell. The membrane that surrounds the cell merges with the membrane of the
secretory granule. As the two membranes have similar chemical structure, being
lipoprotein, each can dissolve in the other at the point of contact. When this
occurs a gap forms in the cell's membrane and the interior of the granule is
exposed to the exterior of the cell; the peptide that will stimulate cancer
growth can depart through this pore that has formed. This process is termed
exocytosis; the gap is called an exocytotic pore. Such pores can now be studied
at the nanoscale level.
Clearly if we could
alter the release of the compounds from cells then novel treatments for cancer
may eventuate. The emerging evidence that disruption of normal exocytosis itself
is implicated in cancer growth makes the characterisation of the process even
more important. However there is little understanding of how the formation of
the pores and their function in diseases such as cancer, nor how the pores may
be used as a target of treatments.
This work should lead to a new insight of cell responses and communication
and might help in early diagnosis of cell deformation especially in cancer cell
studies. It is important that we advance to investigate live cells in the biochip/bioimprint
system, but there are challenging barriers that require careful consideration
and innovative nanoengineering solutions.
Applications of Bioimprint technique in the formation of 3D biocompatible
scaffolds for tissue engineering is underway.
References
1. Alkaisi, M.M., Muys, J.J., Evans, J.J., "Single
cell imaging with AFM using Biochip/Bioimprint Technology" 2009 invited paper,
Special Issue of International Journal of Nanotechnology on New Zealand Science,
issue3-4, Vol, 6, 355-368, (2009).
2. Alkaisi, M.M.,
Muys, J.J., Evans, J.J.,"Invited paper" "Bioimprint Replication of Single Cells
on a Biochip", BioMEMs and Nanotechnology, Proc of SPIE Vol 6799, U212-U221 ,
2007.
3. Muys, J, Alkaisi, M.M., Evans, J.J., Melville
D.O.S. Nagase, J., Oaruez, G.M., Sykes, P., (2006), "Cellular Transfer and AFM
imaging of Cancer cells using Bioimprint", Journal of Nanobiotechnology, (2006),
4:1. ISSN 1477-3155.
4. Muys, J., Alkaisi, M.M.,
Evans, J.J.(2006) "Bioimprint: Nanoscale analysis by replication of cellular
topography using soft lithography" Journal of Biomedical nanotechnology, Vol 2,
No 1, April 2006, pp 11-15.
5. Muys, J., Alkaisi, M.M., Evans,
J.J. "Cellular replication and AFM imaging using UV-Bioimprint technique",
Nanomedicine: Nanotechnology, biology and Medicine, 2(3) 2006.
6. Muys, J., Alkaisi, M. M. Evans, J. J. and Nagase, J. (2005).
"Analysis of dielectrophoretically trapped biological cells by atomic force
microscopy using an integrated biochip platform". Japanese Journal of Applied
Physics, Vol.44, No.7B, pp.5717-5723.
Copyright AZoNano.com, Prof. Maan Alkaisi (University of
Canterbury)