IT IS JUST BRIEF DESCRIPTION ON MUTATION AND DETECTION USING GOLD NANOPARTICLES .

1. MUTATIONS and DETECTION
OF MUTATIONS USING
GOLD NANOPARTICLES
RAHUL MITRA
M.Sc ,2nd Semester
Roll No. :13
Department Of Materials Science

2. Outline
• Some basic Terminology used in genetics
• What is Mutation
• Different causes
• Different types of mutations
• Effects of Mutations
• Several detection techniques
• Why Gold Nanoparticles?
• Surface plasmon resonance of gold nanoparticles
• Detection using GNps
• Advantages

3. Some terminologies
• Gametocytes: Cells that take part in reproduction.
• Somatic cell: Cells other than gametocytes.
• Nucleus: Brain of a cell.
• Chromosome: A thread like stucture of nucliec acids and protiens found
in nucleus of most living cells.It carries the genetic information in the
form of genes.
• Homologus Chromosome: a couples of homologs are a set of one
maternal and one paternal chromosomes that pair up with each other
during cell division process.
• DNA: Deoxyribonucleic acid or structural unit of chromosome.
• RNA: Ribonucleic acid that takes part in protein synthesis.
• Genes: A gene is a locus or regions of DNA which is made up of
nucleotides and it is the molecular unit of heredity.
• SPR: Surface plasmon resonance
• AuNPs or GNps: Gold nanoparticles.

4. Structural minimization from cell to
genes

5. What is MUTATION
• A sudden change in physical or chemical structure in Genes or
Genetic material.
Or more specifically,
• Sudden changes in the nucleotide sequence of DNA
• May occur in somatic cells (aren’t passed to offspring).
• May occur in gametes (eggs & sperm) and be passed to offspring.
• The result due to mutation is immediate.
• Mutation was first observed by Hugo de vries in Evening prime
Rose (Oenotera lamarkiana) plant.

6. Causes for Mutation
Those substances which causes mutation are called Mutagen.
Thee are two types of mutagens:
1)Chemical: 3 types: i)Base analogs:Analogus to
Nitrogen Base Pair. E.g-5-Bromo
urasil(5-BU)
ii)Alkylating Agents.
iii)Acridindyes:These are
induced mutagens.
2)Physical or Radiation: 2 types.
i)Ionizing: This type of mutagens damage the genetic materials
by ionizing the atoms present there. E.g.:X-rays,α-rays,β-rays.
ii)Non-ionizing: They do not ionize the molecules in present in
the genetic materials. E.g.-UV Rays.

7. Types of Mutation
Generally mutation can divide into 2 main part on basis
of where it is occuring-
1)Chromosomal Mutation.
2)Gene Mutation or Point Mutation.

8. Chrommosomal Mutation
• MORPHOLOGICAL MUTATION:
– May Involve:
– Changing the structure of a
chromosome.
– The loss or gain of part of a
chromosome.
There are 5 types:
i)Deletion
ii)Duplication
iii)Inversion
iv)Translocation
v)Non-disjunction

9. Contd
.

11. Point Mutation
• Change of a single nucleotide
• Includes the deletion, insertion, or
substitution of ONE nucleotide in a gene
• Mainly divided into 3 types:
– 1)Point Mutation
– 2)Inversion
– 3)Frameshift Mutation

12. Frame Shift Mutation
• Inserting or deleting one or more nucleotides.
• Changes the “reading frame” like changing a sentence.
• Proteins built incorrectly.
• There may be 2 chances:
– 1)Addition of one N base.
– 2)Deletion of one N base.

13. • Original sequence:
– WHY DID THE CAT ATE THE FAT RAT…….
• Deletion of one N-base(Frame shift Mutation):
– Let us take Y is being eliminated.
– WHD IDT HEC ATA TET HEF ATR AT……
• Addition of one N-base(Frame shift Mutation):
– Let us take some P is being added.
– WHY PDI DTH ECA TAT ETH EFA TRA T……...

14. Effect of mutation
• A mutation is a permanent change to DNA. These changes occur
when DNA repair mechanisms fail to repair damage, when DNA
replicates incorrectly, or from the deletion or insertion of DNA
segments. Some mutations occur within the lifetime of a single
organism. These somatic mutations involve direct damage to an
organism's DNA from an environmental source. For example,
damage from ultraviolet rays damages DNA in a way that gives
rise to cancerous cells.
• Other mutations are heritable and pass from one generation to
another. One particular heritable mutation causes a deletion of
32 base pairs affecting the human CCR5 protein. Research
suggests that people with this gene possess immunity to bubonic
plague or smallpox, a very beneficial mutation to people at
various periods in human history. Because of higher survival
rates of people with the CCR5 mutation, the mutation persists
into the present day. For modern humans, a CCR5 mutation
means resistance to HIV.

15. Several detection techniques
• Detection of DNA mutations is elementary practice
for medical genetic tests as well as for scientific
laboratory applications. Medical tests and screens
relying on DNA mutation detection include routine
preconception and prenatal genetic screens, and tests
fordisease predisposition. Traditional methods for
mutation detection include sequencing, PCR,
fluorescent in situ hybridization, restriction
fragment length polymorphism ,biosensors and
microarrays.A recent development is detection using
nanoparticles.

16. • Recent studies have demonstrated the use of nanoparticles for
DNA mutation detection.Generally they are used as biosensors.
These methods are based on nanoparticles that are attached to
DNA molecules and change their properties in response to
mutations. We study the interaction between DNA molecules
and unbound nanoparticles.
• Generaly Gold Nano-Particles are used in detection of
SNP(Single Strand Polymorphism) or Point Mutation.

17. Why Gold Nanoparticles(GNp)?
• Within the group of noble metal nanoparticles, gold
nanoparticles are mostly used for biosensor application.
• CHARACTERISTICS:
– 1)Gold Nanoparticles are chemically and biologically inert.
– 2)These have greater biological compatibility than other nano
particles.
– 3)Optical properties like surface plasmon resonance are fluroscence
and chemi-luminescence having better exhibited by Gold
Nanoparticles(gold at the nanoscale can appear red, blue, green, or
brown).
– 4)They have better stability due to the gold-sulphur bonds.
– 5)Production of AuNPs are relatively simple.

18. SURFACE PLASMON RESONANCE OF
GOLD NANOPARTICLES
• Surface plasmon resonance (SPR) is the resonant oscillation of
conduction electrons at the interface between a negative and
positive permittivity 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.
• The exclusive optical properties of AuNPs arise from localized
SPR.
• The oscillation frequency of AuNPs is usually in the visible
region, giving rise to a strong color associated specifically with
SPR-related absorption.

19. SPR in AuNPs (left) results in absorbance of blue-green wavelengths and reflection of
red wavelengths, as seen in a photo of a citrate-capped solution of 13-nm-diameter AuNPs
(right).
The diameter of AuNPs affects the surface plasmon absorption. 13-nm-
diameter AuNPs usually produce an absorbance peak at green-blue
wavelengths (~520 nm) and reflect red wavelengths (~700 nm), and such
solutions, therefore show a rich red color.

20. Detection using GNps
• On the basis of these principle we can detect the Point mutation
by Colorimetric analysis.
• AuNPs have been used as a colorimetric reporter for SNP
sensing based on their unique SPR absorption properties where
AuNP aggregation or redispersion of an aggregate triggers a
visible color change from PURPLE to RED.
• Free ssDNA can adsorb onto unmodified AuNPs due to the
electrostatic effects of nitrogen atoms in the bases, protecting
AuNPs from aggregating in a high ionic strength environment. In
contrast, dsDNA cannot achieve such protection .Single-base
mismatches have been detected by taking advantage of this
difference in electrostatic properties between ssDNA and
dsDNA.

21. • At high temperature, the purple
color of the perfect match solution
would not change to red, whereas a
mismatched solution becomes red as
the assembled gold nanoparticles
separate. Using melting analysis, the
position of the point mutation could
be identified. This assay provides a
convenient colorimetric detection
that enables point mutation
identification without the need for
expensive mass spectrometry.

22. Advantages
• The major advantages of this technique
over the conventional techniques are
– Low cost, low sample volume, highly
sensitive and specific AuNP-based
colorimetric sensor platforms for the
detection of DNA and small molecules.
– This is a naked-eye detection of cancer-
related point mutations.
– Need less time(approx. 5mins).

23. References..
• Youtube
• Internet

24. Thank You