BY

Shahanoor Momin

(M.PHARM)

Guided by

Mrs. Maushumi Kulkarni

ALLANA COLLEGE OF PHARMACY

Pune

Gold nanoparticles(AuNPs), also called gold colloids.

In a study published in the July 2007 issue of Analytical Chemistry, scientists from Purdue University use of gold nanoparticles to detect cancer cells and breast cancer.

Lasers that react with gold nanoparticles could be used to destroy cancer cells. Or nanoparticles could be used as targeted drug delivery systems.

procedure works by identifying the proteins found on the exteriors of cancer cells.

Different types of cancer used to detect like oral cancer, breast cancer, and these cancer have different proteins on their surfaces that serve as unique markers.

Gold nanoparticles shaped like rods, use specialized antibodies to latch onto the protein markers for breast cancer.

Gold nanorods could be used to detect

cancer stem cells.

After the nanorods bind to proteins in a

blood sample, and they scatter light .

Each protein-nanorod combination

scatters light in a unique way, allowing for

precise diagnoses.

AuNPs are the most stable metal nanoparticles.

Colloidal gold was used to make ruby glass (vide infra), that “gold must be present in such a degree of communition that it is not visible to the human eye”

Nanoparticles as drug delivery systems enable unique approaches for cancer treatment.

Nanoparticles have optical, Magnetic, Chemical and structural Properties that set them apart from bulk solids with potential application in medicine.

Gold (Au) Nanoparticles exhibit a combination of physical, chemical, Optical & Electronic properties.

Au+3 ions are reduced to neutral gold atoms, where citrate ions act as both a reducing agent and a capping agent.

This formation of gold nanoparticles can be observed by a change in colour since small nanoparticles of gold are red and big particle are yellowish colour.

The presence of this colloidal suspension can be detected by the reflection of a laser beam from the particles.

Add 20 ml of 1.0 mm chloroauric acid(HAuCl4 to

a 50 ml beaker, solution is rapidly stir and boil.

To the rapidly-stirred boiling solution, quickly add

2 ml of a 1% solution of trisodium citrate

dihydrate[Na3C6H5O7.2H2O]. The gold sol

gradually forms as the citrate reduces the gold(III).

Remove from heat when the solution has turned

deep red.

The presence of a colloidal suspension can be detected by

the reflection of a laser beam from the particles.

Because a laser pointer emits polarized light, the pointer

can be oriented such that the beam appears to disappear.

When the beam from the laser is visible in one view,

it is invisible in the view

perpendicular to the first.

Before the addition of the reducing agent, the gold is

in solution in the Au+3 form. When the reducing agent

is added, gold atoms are formed in the solution, and

their concentration rises rapidly until the solution

exceeds saturation. Particles then form in a process

called nucleation. The remaining dissolved gold atoms

bind to the nucleation sites and growth occurs.

A colloid is a homogeneous dispersion of particles in a solution which are so small as to not settle out easily

A sol is a specific type of colloid characterized as a solid dispersed in a liquid

The particles experience the constant buffeting of Brownian motion which also helps to keep them in suspension.

Formulation of Au nanoparticle is a three step process:

1. nucleation,

2. growth, and

3. coagulation.

Nucleation is the creation of nuclei upon which growth can occur

This is a redox reaction: oxidation of the citrate ion produces the necessary reducing reagent for the gold: acetone dicarboxylic acid The acetone dicarboxylic acid is the limiting reagent for nucleation

The formation of this molecule in the solution creates an induction period before which no product can be seen

The nature of the nucleation curve is evidence of an autocatalytic reaction

Growth is the addition of more gold particles to the existing nuclei.

The process of growth stops when all of the gold is used.

The rate of growth is a first order in the gold nuclei size.

Creation of the larger gold particles, such as 20 nm, requires a coagulation of multiple (smaller) twins of various shapes

A conglomeration of multiple nuclei into particles can be large enough to disturb the stability and fall out of the colloid

Control of the coagulation process during preparation determines the size, structure, and size distribution of the particle

Angiogenesis, the formation of new blood vessels isessential for the growth and progression of tumors.

Angiogenesis is also important for the promotionand maintenance of other diseases like neoplasiaand rheumatoid arthritis.

Nanogold particles binds to heparin binding growthfactor like VEGF165 and bFGF and inhibit theiractivity and prevent progress of diseases.

But GNPs does not inhibit the activity of nonheparin-binding growth factors like VEGF121 andEndothelial Growth Factor (EGF)

Gold nanoparticle is simple for diagnosis.

It is less invasive.

It is provides increased contrast for diagnosis of oral cancer.

It is nontoxic to human beings.

It does not photobleaching or blinking which is inherent to many other fluorophores.

Opticle signal of nanoparticles may not be as strong as quantum dot.

It exhibits difficulties like biocompatibility, in vivo kinetics, and tumour target efficacy.

It leads to acute and chronic toxicity.

Reticuloendothelial system gets affected in presence of gold nanoparticle.

APPLICATION OF GOLD NANOPARTICLES

The peptide functionalised gold nanoparticles that wesynthesised are very effective in the deliberate activationor inhibition of angiogenic genes.

As compared to other metallic nanostructure , GNPsprovide advantage of their simple and fast preparationand bioconjugation.

The researchers also found that the gold particles couldbe used as effective tools in cellular nanosurgery.

Gold nanoparticle detect the various cancer likebreast cancer, oral cancer , respiratory cancer, andother diseases like neoplasia and rheumatoidarthritis.

The functionalized gold nanoparticles selectivelyattach to the aggregate of amyloidal protein formed inAlzheimer Disease. The microwaves of certainfrequency are irradiated on the sample. Resonancewith the gold nanoparticles increases the localtemperature and destroy the aggregate.

Gold Nanotechnology in the age of innovation is gold for good.

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