This document provides an overview of forensic analysis and the use of biosensors in various forensic applications. It discusses the definition of forensic science and some key branches including forensic chemistry, toxicology, doping analysis, and poisons analysis. Forensic chemistry involves the use of analytical techniques like chromatography and spectroscopy to identify unknown substances. Forensic toxicology analyzes biological samples to determine the presence of toxins, drugs, or poisons. The document also describes how biosensors have been used to detect substances like cocaine, testosterone, and arsenic.

1. Forensic Analysis
PhD Seminar( I ) in Analytical Chemistry
By:
Fereshte Mohamadi
January 2016

2. Outline
2
o Forensic Science Definition
o Forensic chemistry
o Forensic toxicology
o Doping analysis
o Illicit drugs analysis
o Poisons analysis

3. Forensic Science
3
 Definition:
The application of scientific technology to supply
accurate and objective information reflecting the
events that occurred at a crime.

4. The History of Forensic
Science
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 700s Use fingerprints
 1248 Distinguish drowning from strangulation
 1609 Systematic document examination
 1888 Forensic science was significantly applied
 1902 The first steps towards establishing forensic science as an academic discipline.

5. Forensics Branches
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 Forensic Chemistry: the study of the properties of matter, including structure and interactions
 Forensic Toxicology: the study of poisons
 Forensic Mathematics: finding relationships and patterns in crime scenes and evidence
 Forensic Odontology: the study of the structure, development, and abnormalities of teeth
 Forensic Reconstruction: recreating the crime scene
 Forensic Technology: solving crimes with advanced technology
 Forensic Anthropology: the study of the human body and social relationships
 Forensic Nursing: helping victims of sexual assault
 Forensic Photography: use photos to document the scene of a crime
 Forensic Pathology: determining the cause of death and identity of a person; autopsies are performed to
discover the cause of death or injuries

6. Forensic chemistry
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 Forensic chemistry: The application of chemistry and its subfield, forensic toxicology, in a
legal setting.
 High-performance liquid chromatography
 Gas chromatography-mass spectrometry
 Mass spectrometry
 Atomic absorption spectroscopy
 Thin layer chromatography
 Fourier transform infrared spectroscopy
 Biosensors
 Forensic specialists in this field
have a wide array of different
methods and instruments to help
identify unknown substances

7. Affinity sensor
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Affinity receptors
 Antibodies
 Lectins
 Enzymes
 Aptamers

8. Forensic toxicology
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 Forensic toxicology is the use of toxicology and other disciplines such as analytical chemistry,
pharmacology and clinical chemistry to aid medical or legal investigation of death, poisoning, and
drug use.
 The forensic toxicologist must determine which toxic substances are present, in what
concentrations, and the probable effect of those chemicals on the person.
Sources of Biological Evidence
Blood
Semen
Saliva
Teeth
Bone
Hair
Tissue
Feces
Urine
Skin Cells
Sweat
Gastric content

9. Forensic toxicology
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Biosensors applied to forensic toxicological analysis
Poisons
Toxins
Microorganisms
Alcohol
Illicit drugs
Doping

10. Doping analysis
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Doping in sport is defined as the recourse, by
sportsmen or sportswomen, to doping substances
or methods banned by the World Anti-Doping
Agency (WADA)
The coupling of GC and LC with MS allows
the sensitive and selective detection of WADA
banned compounds and represents the most
utilized method to date
Affinity-based biosensors (ABBs)
also started to be considered in
doping control analysis because
they are cheap, easy to use and
sufficiently selective analytical
devices that integrate a
biotransducer on the surface of a
physico-chemical transducer,
allowing the detection of
interaction with the analyte under
Investigation.

11. Anabolic steroid
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Chemical structure of the natural anabolic hormone
testosterone, 17β-hydroxy-4-androsten-3-one
Chemical structure of the synthetic
steroid methandrostenolone (Dianabol).
17α-Methylation (upper-right corner)
enhances oral bioavailability.

12. Surface plasmon resonance
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Surface plasmon resonance (SPR) is the resonant oscillation of conduction electrons at the interface
between a negative and positive permitivity material stimulated by incident light. The resonance condition
is established when the frequency of incident photons matches the natural frequency of surface electrons
oscillating against the restoring force of positive nuclei. SPR in subwavelength scale nanostructures can
be polaritonic or plasmonic in nature.
SPR is the basis of many standard tools for measuring adsorption of material onto planar metal (typically
gold or silver) surfaces or onto the surface of metal nanoparticles. It is the fundamental principle behind
many color-based biosensor applications and different lab-on-a-chip sensors.

13. SPR sensors
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14. Detection of testosterone
14Mitchell et al. Biosensors and Bioelectronics 24 (2009) 2177–2183
Gold
Self assembled monolayer

15. Illicit drugs analysis
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Forensic drug chemists analyze samples of unknown materials including powders ,liquids and stains to
determine the chemical identity or characteristics of the compounds that make up the sample.
Stimulants are compounds that show both a direct effect on the CNS and a peripheral effect. They
comprise a large number of drugs whose chemical structure derives from adrenaline, a substance
produced by the human body under stress conditions. All stimulants exert a strong effect of
excitation on the body and on the brain.
cocaine structure

16. Detection of cocaine
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J.P. Hilton et al. Sensors and Actuators A 166 (2011) 241–246
Förster resonance energy transfer (FRET)

17. Poisons analysis
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Arsenic is a wide spread heavy metal which has influenced human history more
than any other element or toxic compound. In terms of abundance, it ranks20th in
the earth's crust,14th in sea water and 12th in the human system.
In nature, arsenic exists in both organic and inorganic forms, having different
speciations such as arsenate [As(V)] and arsenite[As(III)].
It is great difference in toxicity between the two oxidation states, being As(III)
about sixty times more toxic.
Arsenic has been associated with mutagenic and carcinogenic potential up on pro-
longed exposure

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19. Bacteria sensor–reporters for arsenic
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Gene expression

21. Gene expression
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22. When no arsenic enters the
cell
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Promoter
ArsR protein represses the transcription of the arsenic
defense system genes.
No Arsenic Resistance Proteins

23. When arsenic enters the cell
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RNA Translation
Arsenic
Resistance
Proteins

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When arsenic enters the cell

25. Bacteria sensor
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An extra copy of the operator–promoter DNA fused to the arsR
gene and a gene for a reporter protein are added to the cell.

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Bacteria sensor

27. Conclusions
Biosensors have emerged as important tools in different areas of forensic analysis.
Biosensors possess to be used as rapid, reliable and affordable analytical tools in this branch
of modern Analytical Chemistry that is characterized by the legal context affecting both the
work implementation and the results, and the variety of analytes and samples able to be
investigated.
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28. References
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 Maxime Julien et al. Talanta,(2016) 147, 383-389.
 Franco Mazzei et al. Bioanalysis (2014) 6(2), 225–245.
 C. Cattaneo et al. Forensic Science International (2015) 254, 29–35.
 P. Yáñez-Sedeño, et al., Biosensors in forensic analysis. A review, Anal. Chim.
Acta(2014), http://dx.doi.org/10.1016/j.aca.2014.03.011
 O. Drummer. Encyclopedia of Forensic and Legal Medicine (2nd Edition), 2016, 602-607.
 J.P. Hilton et al. Sensors and Actuators A 166 (2011) 241–246.
 Mitchell et al. Biosensors and Bioelectronics 24 (2009) 2177–2183.
 Hardeep Kaur et al. Biosensors and Bioelectronics 63(2015)533–545.
 Merulla et al..Curr.Opin.Biotechnol. (2013)24(3),534–541

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30. Just A Thought
It’s not what you know that hurts
you, its what you think you know
and it’s not so . . .
Mark Twain
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