Raman spectroscopy can be used to develop cell-based biosensors for toxin detection. Living cells act as sensor elements, as Raman spectroscopy can identify biochemical changes in cells exposed to toxins. It can detect a wide range of toxins at low concentrations quickly in an non-invasive manner by measuring the biological reactions of single cells, cell layers, or cell networks. Raman spectra of live cells contain peaks corresponding to DNA and RNA that distinguish healthy from dead cells, and can monitor changes in cells interacting with drugs. This technique has been applied to detect two toxic agents of bioterrorism and chemical warfare.

2. Raman Spectroscopy cell-
based biosensors

3. Abstract:
 Different toxic chemicals have
different effects on living cells
and induce different
biochemical changes related to
cell death mechanisms.
 Raman Spectroscopy is a
powerful technique use to
identify a large range of toxins
at low concentrations and in
short times.

4. • Introduction:
• What are biosensors..
• A biosensor is a device that can detect and identify toxic
within a cell or tissue. These cells and tissues act as biosensor
molecules.

5. Type of biosensor molecules:
 The molecular-based
biosensors use biological
active substances such as
 Enzymes
 DNA
 antigens
 antibodies

6. How Raman spectroscopy take part in cell
based biosensors…
 In Raman spectroscopy cell-based biosensors living cells use
as sensor element .
 The biological reaction of cells is measured following the
exposure of single cells, layers of cells or networks of living
cells to toxic agents.
 That technique undergone significant developments during
the last decade.

7. 1. Raman scattering and
instrumentation:
• laser is use in the visible
or near-IR region ,
diffraction grating is used
to disperse light,
spectrometer is equipped
with a notch to reject the
elastically scattered
photons.

8.  Variations in the intensity of
the intrinsic light emitted
by bioluminescent bacteria
can be used to detect toxic
chemicals such as polycyclic
aromatic hydrocarbons and
phenols.

9. Applications:
1. Raman spectra of live cells :
 Raman spectra of live cells
corresponds to all biopolymers
found in cells .
 The main peaks are found at 788
cm-1 phosphodiester bonds in
DNA and 813 cm-1 phosphodiester
bonds in RNA.
 The phosphate peaks are
particularly useful to determine
main distinction between DNA and
RNA.

10. 2. Live versus dead cells :
 A first requirement for a biosensor is the ability to
discriminate between healthy and dead cells.
 To test this ability, Raman spectra of healthy and dead cells
were compared to identify the main spectral differences.

11. Comparison between Raman spectra of healthy and dead cells.

12. 3. Interaction of cells with drugs :
 Raman spectroscopy can be used for
developing cell-based biosensors for
monitoring the interaction of cells with
drugs.
 Using this analysis method, it was found
that the concentration of DNA decreased
by ~40% and ~90% after 24 and 48 hours .

13. 4. Toxicology of chemical
and biological warfare :
 Ricin and sulphur mustard
two toxic agents of
bioterrorism and chemical
warfare significance was
investigated by Raman
spectroscopy.

14. Advantages:
 Detect and identify a large range of toxins at low
concentrations .
 Short time is require .
 Non invasive technique.
 Non destructive

15. Conclusion:
 There are significant spectral differences in dead cells
compared to healthy cells, differences which can be used as
markers for cell viability
 This technique use to identify two important toxic agents,
ricin and sulphur mustard.