Focused on the different processes separating density based products, mainly bioproducts

2. Density :
A Property for Bioseparation
Group Members -
Eilma Akhond
Farjana Afroj
Razib Datta Shubhra
Nazmul Haque Rony

3. Bioseparation ???
Bioseparation refers to the systematic study of the scientific and engineering
principles utilized for the large-scale purification of biological products.
Actually it is largely based on chemical separation processes which is called
multi-technique separation processes, i.e., two or more separation techniques
are used for the separation of a single biological product.
Density ???
Bioproduct ???
Bioproducts are the products originated from living organism. Bioproducts
show some unique properties, such as- size, density, diffusivity, shape,
polarity, solubility, electrostatic charge, volatility, thermal stability,
isoelectric pH etc. These properties are the Physico-chemical basis of
separation in bioseparation processes.
The density of a substance is its mass per unit volume. The symbol most
often used for density is ρ or, D. Mathematically,
The mass of atoms, their size, and how they are arranged determine the
density of a substance.

4. How ???
Density is a property in Bioseparation
 Density is a characteristic property of a
substance. That is why it can be a property in
bioseparation, such as, for the solution
containing different densed particles, when
gravity is the sole method for separation, density
becomes a fundamental property in bioseparation
processes.
 In a solution, under Gravity or centrifugal force,
whose density is higher than that of the solvent
sink and particles that is lighter than that float on
the top. The greater the difference in density, the
faster they move. If there is no difference in
density (isopyknic conditions), the particles stay
steady.
Fig: Schematic diagram of different
densed particles moving at different
region in a solution during a
separation process (centrifugation).

5. Bioseparation Processes
The particles having density differences can be separated
from each other by applying external forces. According
to this principle, some bioseparation processes are used
for the separation of density based bioproducts. These
are-
1. Centrifugation
2. Sedimentation
3. Flotation

6. Centrifugation
• Centrifugation is a process which separates particles from a solution
according to their size, shape, density, viscosity of the medium and
rotor speed.
• When the mixture is introduced at a location within a liquid medium
which is then subjected to an artificially induced gravitational field,
this process utilizes density difference between the
particles/macromolecules and the medium.
• It is used in particle-particle separation in liquid medium. For
example-
the fractionation of sub-cellular organelle,
the separation of plasmid DNA from chromosomal DNA, and
 the separation of mature cells from young cells.

7. When cells or tissues
are homogenized by
suspending them in an
isotonic sucrose
solution, plasma
membrane is ruptured
but the other
organelles will remain
intact. These
components have
different size and
densities. So when
different
centrifugation forces
are applied, we get
different particles in
supernatant and pellet.
Differential centrifugation of sub-cellular component

8. Sedimentation
• Sedimentation is the process of letting suspended material settled
by gravity which is a natural force. Other forces may also perform in
sedimentation, such as, centrifugal acceleration or
electromagnetism.
• Sedimentation is continuously used in the bioseparation process to
separate biological molecules on the basis of buyoant densities. This
process are also able to provide details on the purity of biological
samples and information on molecular weights quite accurately.
In sedimentation, the particles which are
denser than the liquid medium would settle
and form a zone with very high particulate
concentration. This is referred to as the
sediment and the clear liquid left behind is
referred to as the supernatant. This has been
shown in the flanking figure.

9. Equilibrium sedimentation
• Equilibrium sedimentation is a
typical sedimentation process.
• It uses a gradient of a solution
such as Caesium Chloride or
Sucrose to separate particles
(proteins, nucleic acids,other
macromolecules etc.) based on
their individual densities
(isopycnic solution) and analyze
molecules concentrated as
bands where the molecule
density matches that of the
surrounding solution.
• It is also known as a purifying
process for differential
centrifugation.
Fig: A schematic diagram of
equilibrium sedimentation

10. Flotation
• Flotation is the process of separation of the particles according
to their relative capacity for floating on a given liquid. This
process is used in particle-liquid separation process.
• This principle, utilized in floatation, is based on hydrophobicity
differences. The increase in hydrophobicity, the decrease in
density. So the hydrophobic particles become lighter than the
liquid and other hydrophilic particles. Then the hydrophobic
particles would tend to float and hence concentrate near the top
of the container in which the suspension is held.
• Industrially, floatation is used in the separation of the particles
of a mass of crude ore. This process is also used in mining,
waste water treatment and paper recycling.

11. Froth Floatation Process
• In mineral treatment and mining,
froth flotation is used as a process
for separating minerals from crude
ore by taking advantage of
differences in their hydrophobicity.
Most kinds of minerals require
coating with a water repellent
(surfactants) to make them float.
This increases hydrophobicity
differences.
• By coating the minerals with small
amounts of chemicals or oils,
particles of the minerals remain
unwetted and will thus adhere to air
bubbles.
• These hydrophobic materials take
place in forth.

12. Thank You

13. Any Question?????