Nucleic Acid Based Biosensors

1. COURSE TITLE :-Molecular Pathology and Molecular diagnosis
COURSE NO. :-MBBD523
COURSE CREDIT :- 2(2+0)
SUBIMTTED T0:- SUBMITTED BY:-
Dr. Subha Banarjee mam Name:- Neelima singh
Dept. of PMBB College Id:- 20200300
Dept. :- PMBB
Nucleic Acid Based
Biosensors

2. CONTENTS
 What is biosensors
 Father of biosensors
 Component of biosensors
 Basic characteristics of biosensors
 Types of biosensors
 Example of biosensers
 Nucleic acid based biosensors
 Applications of biosensors
 References

3. What is biosensors
 A biosensor is an analytical device which is used to determine
the presence and concentration of a specific substance in a
biological analyte
 In simple words, it is an analytical device which converts an
biological responce into an electrical signal

4. Father of Biosensors
 Professor Leland C. Clark (1918–2005)
 The first and the most widespreadly used commercial
biosensor: the blood glucose biosensor – developed by Leland
C. Clark in 1962.
 1962: First description of a biosensor: an amperometric
enzyme electrodre for glucose (Clark)

5. Components of Biosensors:

6.  Sample/ Analyte:- There are materials which are
measured.( Urine, blood, Protein,Vitamins, Peptide)
 Biological molecules:-These molecules intract with analyte
and produce physical changes. (antibody, cells, Nucleic
acid, enzyme, microorgannism)
 Transducer:- convert the biochemical activity into
electrical energy.
 ELECTRONIC SYSTEM:-Combination of electronic
devices i.e. Amplifier, signal processer and display device
that are primarily responsible for the display of the results
in a user-friendly way.
Component of
biosensors

7. Working of biosensors

8. Characteristics of biosensers
 1. LINEARITY:- Linearity of the sensor should be high for the
detection of high substrate concentration.
 2. SENSITIVITY:- Value of the electrode response per
substrate concentration.
 3. SELECTIVITY:- Chemicals Interference must be
minimized for obtaining the correct result.
 4. RESPONSE TIME:- Time necessary for having 95% of
the response.

9. Classification of biosensors

10. Biosensors
 1 Calorimetric biosensor:- They measure change in tempreture due to
realeasde or absorbe of heat.
 2 Potentiometric biosensor:- They measure potential difference arising
due to a redox reaction.
 3 Amperometric biosensor:-They measure current(flow of electrons)
during a reaction.
 4 Conductometric biosensor:- They measure change in electrical
conductivity during a reaction.
 5 Acoustic wave biosensor:- They measure electric field developed by
piezo-electric field.
 6 Optical biosensor:- They measure light arising from the action of
enzyme luciferase.

11. Some Example of biosensors
• Alcohol biosensors
• Glucose biosensor
• Urea biosensor
• Inosine biosensor
• Hypoxanthine biosensor etc

12. Nucleic acid based biosensors
(NABs)
 Nucleic acid biosensors can be used to detect DNA/RNA
fragment or either biological or chemical species.
 A nucleic acid based biosensors employs as the sensing
element an oligonucleotide, with a known sequence of base, or
a complex structure of DNA or RNA.
 NABs primarily use deoxyribonucleic acid (DNA), ribonucucleic
acid (RNA), peptide nucleic acid (PNA), and aptamers (both
DNA and RNA) as oligonucleotide probes.
NUCLEIC ACID:-
 Biopolymers/large biomolecules.
 Includes DNA and RNA
 Made from monomers.
Known As nucleotides.

13. DNA-Deoxyribonucleic acid
 DNA - a polymer of
deoxyribonucleotides.
 Consist of:
 Deoxyribose=5 pentose
sugar
 Phosphate group
 bases
 Adenine ,Guanine (purines)
 Cytosine ,thymine
(pyrimidines)
 DNA is a double helix with
2 strands which gives
ladder like shape with base
pairs

14. RNA- Ribonucleic acid
 RNA is a polymer of
ribonucleotides
 Usually single stranded and
helical in structure.
 Consist of:
 Ribose=5 pentose sugar
 Phosphate group
 bases
 Adenine ,Guanine
(purines)
 Cytosine ,urecil
(pyrimidines)
 linked together by
phosphodiester linkage.

15. Nucleic Acid intraction
 Biosensors that employ nucleic acid interactions can be referred to
as genosensors.
 The recognition process is based on the principle of
complementary base pairing, adenine:thymine and
cytosine:guanine in DNA.
 If the target nucleic acid sequence is known, complementary
sequences can be synthesized, labeled, and then immobilized on
the sensor.
 The hybridization probes can then base pair with the target
sequences, generating an optical signal.

16. Hybridization

17. Design Of NABs

18. Type of NABs
 Optical NABs
 Electrochemical NABs
 Piezoelectric NABs

19. Optical NABs
 The most commonly used method in NABs.
 Colorimetric for color -Measure change in light adsorption
 Photometric for light intensity – Detect the Photon output
 Optical biosensors are the devices that utilize the principle of
optical measurements (absorbance, fluorescence,
chemiluminescence etc.)
Aborbance α Analyte concentration

20. Piezo-electric NABs
 Piezoelectric Biosensors are also known as Acoustic
Biosensors .
 They are based on the principle of sound vibrations i.e.
acoustics.
 When a mechanical force is applied to a piezoelectric
biosensor, they produce an electrical signal.
 Change in frequency

21. Piezoelectric effect

22. Electrochemical NABs
 Carbon Nano Tubes (CNTs) are playing a leading role in development of
electrochemical DNA based biosensors.
 Principle: Fluroscence α Concentration of Target DNA
 Steps involved in electrochemical DNA hybridization biosensors:
 1. Formation of the DNA recognition layer
 2. Actual hybridization event
 3. Transformation of the hybridization event into an electrical signal
 Detection of:-
 Hybridized DNA
 DNA-binding drug
 Glucose concentration

23. Step involve in electrochemical DNA
hybridization biosensors

24. The scope of biosensors
 DNA chips
 The lab-on-a-chip applied science
 The micro fluid machines
 The nano-biosensors
 The nanotechnology
 Biosensor fabrication and
 The biomaterials

25. Applications of Biosensors