Dazzling thing in the Universe {Part -3}

Welcome to the Series of Dazzling thing in the Universe:- (Part -3)

Before making their final death plunge into the Black Hole.

In the disc, debris spins at unfathomable speeds, pulled around by a Black Hole billions of times more massive than our Sun. Friction in the accretion disc generates heat on a level difficult to fully appreciate. Just as hot things glow, the disc does too.

So, brightly it has its own name- A Quasar.

Quasars

 Quasars shine thousands of times more brightly than even the brightest stars.

Not just stars, it's scarier than that Quasar shine thousands of times more brightly than galaxies containing billions of stars.

The first identified Quasar, 3C273, has an absolute magnitude of -26.7,

3C 273 Qusar

 making of it 4 trillion times brighter than our Sun about 100 times more luminous than the amount of light produced by the entire Milky Way.

If you put 3C273 33 light years away from us it would shine as brightly as our Sun a mere 8 light minutes away. Blocking the brightness of a Quasar with the corona graph reveals that the Quasars exist in the centres of galaxies that are larger than them in area, but are nonetheless drowned out by thin light.

Such Galactic centres are called Active Galactic Nuclei.

The bulk of their energy spewing forth in the form of a powerful radiation jet, the length of which puts even our Solar System to shame.

The visible part of the jet in this photograph, for instance, is so long it could stretch from the Sun to Pluto and back, 1 and a half million times.

Now, specifically, if a large portion of this ejection energy heads towards Earth, it's responsible for what we call a Quasar, but if Earth is right and the Active Galactic Nucleus sights, it's got a scarier name; Blazar. 

Blazar

 It's Blazar that clocked in the greatest brightness ever observed.

At historically high levels of activity, it registered in absolute magnitude of -31.4.

To put this brightness of Quasars in yet another perspective, take a look at the one hundred thousandth picture snapped by the Hubble Telescope.

Preparation of nanoparticles by Ionic gelation

Chitosan, sodium alginate, dextran and gelatin are hydrophilic biodegradable polymers which may be used for the preparation of nanoparticles by coacervation or ionic gelation method. This method involves a preparation of two aqueous phases, one phase containing polysaccharides (alginate, gellan and pectin) is dissolved in water or in weak acidic medium and other phase containing a polyanion dissolved in water. This solution is then added drop wise under constant stirring. When electrostatic interaction takes place between two aqueous phases, coacervates are formed and when two molecules interact due to ionic force, resulting in transition from liquid phase to gel phase at room temperature. The beads are then removed by filtration or centrifugation, washed with distilled water and dried using lyophilized.

 

Structural representation of the nanoparticle preparation by ionotropic gelation method. A: Sodium Tripolyphosphate, B: Chitosan, C: Chitosan nanoparticles

Advantages of ionic gelation method:-

1. · Simple and mild.
2. · In this method, reversible physical cross linking by electrostatic interaction   occurs instead of chemical cross linking.
3. · No use of organic solvents therefore avoids the possible toxicity and other undesirable effects.
4. ·  Used at large scale as well as on lab scale.
5. ·  The particle size and distribution can be easily monitored by changing the amount of counter ions.

Limitations of Ionic gelation method

1. ·This method can only be used for ionic species.
2. ·The size of particles only depends on physical interaction and there is no involvement of chemical reaction.
3. · Only water soluble substances are used for this method.

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Potential, Advantages, Methods of preparation of Nanoparticles

Potential uses of nanoparticulate drug delivery systems;

• ·         Creating fluorescent biological labels for important biological markers.
• ·         Drug delivery system
• ·         Gene delivery systems in gene therapy
• ·         For biological detection and diagnosis of disease causing organisms.
• ·         Protein detection
• ·         Isolation and purification of biological molecules and cells in research
• ·         DNA probing
• ·         Genetic and tissue engineering
• ·         Tumour detection
• ·         In MRI studies
• ·         In Pharmacokinetic studies

Advantages of nanoparticles over other conventional formulations :

Nanoparticles have many advantages over other conventional drug delivery systems. Certain properties like surface hydrophobicity and surface charge needs to be altered so as to increase the uptake of nanoparticles into cells which can be done by judiciously manipulating the use of polymers. Coating the nanoparticles with chitosan which is positively charged significantly enhances the uptake and modulates the drug efflux of anticancer agents. Moreover, attachment of poly (ethylene glycol) like moieties to the surface of nanoparticles increases the hydrophilicity and decrease the uptake by macrophages.

Methods of preparation of nanoparticles :

Nanoparticles can be prepared from a variety of materials such as proteins, polysaccharides and synthetic polymers. The following factors must be taken in consideration while preparation of the nanoparticles

(a) Size of nanoparticles.

(b) Inherent properties of the drug, aqueous solubility and stability.

(c) Surface characteristics such as charge and permeability.

(d) Degree of biodegradability, biocompatibility and toxicity.

(e) Desired drug release profile.

(f) Antigenicity of the final product.

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