It is an important tool in biochemical research. Which through rapid spinning imposes high centrifugal forces on suspended particles, or even molecules in solution, and causes separations of such matter on the basis of differences in weight.

1. ULTRACENTRIFUGATION
Tapeshwar Yadav
(Lecturer)
BMLT, DNHE,
M.Sc. Medical Biochemistry

2. Centrifuge
A centrifuge is a device for
separating particles from a
solution according to their size,
shape, density, viscosity of the
medium and rotor speed.

3. HISTORY
 Swedish Biochemist Theoder
Svedberg invented the
Ultracentrifuge in 1923.
 And he won the Novel Prize
in chemistry in 1926 for his
research on colloids and
protein using the
ultracentrifuge.

4. Ultracentrifugation Machine

5. ULTRACENTRIFUGATION
It is an important tool in biochemical research. Which
through rapid spinning imposes high centrifugal forces
on suspended particles, or even molecules in solution,
and causes separations of such matter on the basis of
differences in weight.
Example;
Red cells separated from plasma of blood, nuclei from
mitochondria in cell homogenates, one protein from another in
complex mixtures. And also isolation of macromolecules such as
DNA, RNA, Lipids etc.
 Its rotational speed up to 150,000 rpm.
 It is creating a centrifugal force up to 900,000 x g.

6. TYPES
1. Analytical ultracentrifugation:- The aim of Analytical
ultracentrifugation is use to study molecular interactions
between macromolecules or to analyse the properties of
sedimenting particles such as their apparent molecular
weight.
2. Preparative ultracentrifugation:- The aim of Preparative
ultracentrifugation to isolate and purify specific particles
such as subcellular organelles.
There are two types of ultracentrifugation:

7. Analytical ultracentrifugation
Two kinds of experiments are commonly performed
on these instruments:
1. Sedimentation velocity experiments:- Aim of SVEs to
interpret the entire time-course of sedimentation, and
report on the shape and molar mass of the dissolved
macromolecules, as well as their size distribution.
2. Sedimentation equilibrium experiments:- SEEs are
concerned only with the final steady-state of the
experiment, where sedimentation is balanced by
diffusion opposing the concentration gradients, resulting
in a time-independent concentration profile.

8. Preparative ultracentrifugation
It is to isolate specific particles which can be reused
1. Differential ultracentrifugation:- Differential
centrifugation is a common procedure in microbiology
and cytology used to separate certain organelles from
whole cells for further analysis of specific parts of cells.
2. Density gradient ultracentrifugation:- Based on density
difference. There are two types of density gradient
ultracentrifugation's under preparative
ultracentrifugation such as.
1.ZONAL or RATE & 2.ISOPYCNIC

9. 1} ZONAL or RATE Centrifugation:
Mixture to be separated is layered on top of a
gradient (increasing concentration down the tube).
Provides gravitational stability as different species.
Move down tube at different rates.
2} ISOPYCNIC Centrifugation:
 Isopycnic means “of the same density”.
 Molecules separated on equilibrium position.
 Each molecule floats or sinks to position where
density.

10. Schematic presentation of a Ultracentrifuge:
Fig; A Beckman Ultracentrifugation.

11. Functions of analytical ultracentrifugation:
Analytical
 Uses small sample size (less than 1 ml).
 Built in optical system to analyze progress of
molecules during centrifugation.
 Uses relatively pure sample.
 Used to precisely determine sedimentation coefficient
and MW of molecules.
 Beckman Model E is an example of centrifuge used for
these purposes.

12. Functions of preparative ultracentrifugation:
Preparative
 Larger sample size can be used.
 No optical read-out collect fractions and analyze them
after the run.
 Less pure sample can be used.
 Can be used to estimate sedimentation coefficient and
MW.
 Generally used to separate organelles and molecules.
Most centrifugation work done using preparative
ultracentrifuge.

13. Rotor
 Four types of rotors are available for ultracentrifugation,
1. Fixed-angle rotor,
2. Swinging-bucket rotor,
3. Vertical rotor and
4. Near-vertical rotor.
 Rotors are made from either aluminum or titanium, or from
fiber-reinforced composites.
 A titanium rotor is designated by T or Ti, as in the Type 100 Ti,
the SW 55 Ti, or the NVT 90 rotor.
 A composite rotor (fiber) is designated by C, as in VC 53.
 A aluminum rotor is designated by AC, as in VAC 50.
 Rotors without the T, Ti, C, or AC designation (such as the Type
25) are fabricated from an aluminum alloy.

14.  Titanium rotors are stronger and more chemical resistant than
the aluminum rotors.
 Exterior surfaces of titanium and composite rotors are finished
with black polyurethane paint.
 Titanium buckets and lids of high-performance rotors are
usually painted red for identification.

15. 1.FIXEDANGLE ROTOR
 Fixed-angle rotors are general-
purpose rotors that are
especially useful for pelleting
subcellular particles and in
short column banding of
viruses and subcellular
organelles.
 Tubes are held at an angle
(usually 20 to 45 degrees) to
the axis of rotation in
numbered tube cavities.

16. 2.SWINGING BUCKET
ROTOR
 Swinging-bucket rotor are
used for pelleting, isopycnic
studies and rate zonal studies.
 Tubes are attached to the
rotor body by hinge pins or a
crossbar. The buckets swing
out to a horizontal position.
 Isopycnic studies (separation
as a function of density).
 Rate zonal studies (separation
as a function of sedimentation
coefficient).

17. 3.VERTICAL ROTOR
 Vertical rotors hold tubes
parallel to the axis of rotation;
therefore, bands separate
across the diameter of the
tube rather than down the
length of the tube.
 Vertical rotors are useful for
isopycnic and, in some cases,
rate zonal separations when
run time reduction is
important.

18. 4.NEAR VERTICAL
ROTOR
 Near-vertical rotors are
designed for gradient
centrifugation when there
are components in a sample
mixture that do not
participate in the gradient.
 Tubes are held at an angle
(typically 7 to 10 degrees) to
the axis of rotation in
numbered tube cavities.
 In this rotor used only Quick-
Seal and Opti-Seal tubes.

19. Common Centrifuge Classes and Their Applications
( ) = can be done but not usually used for this purpose.

20. Tube Type and Rotor Compatibility
Rotor Types
Tube Types Fixed-Angle Swinging-bucket Vertical
Thin wall open top No Yes No
Thick wall open top Yes Yes No
Thin wall sealed Yes Some tubes Yes
Oak ridge Yes No No
Types of Rotors and Theirs Applications
Rotor Types Pelleting R or Z-Sedimentation Isopycnic
Fixed-angle Excellent Limited Variable
S-bucket Inefficient Good Good
Vartical Not suitable Good Excellent
N-vertical Not suitable Excellent Good

21. Rotor Balance
 The mass of a properly loaded rotor will be evenly distributed on
the ultracentrifuge drive hub, causing the rotor to turn smoothly
with the drive.
 An improperly loaded rotor will be unbalanced; consistent
running of unbalanced rotors will reduce ultracentrifuge drive
life.
 To balance the rotor load, fill all opposing tubes to the same level
with liquid of the same density.
 Weight of opposing tubes must be distributed equally.
 Place tubes in the rotor symmetrically.

22. Start A Run
Set the RPMs, time, and the temperature of the run by
gently pressing the setup screen.
Never exceed the manufacturer’s stated maximum speed
for any rotor.
Press the run/start button when settings are correct.
Wait until reaching desired speed.

23. After the Spin
 Once a run is complete, make sure the rotor has
completely stopped before opening the centrifuge door.
Never attempt to open the door of a centrifuge or slow the
rotor by hand while the rotor is in motion.
 Please log in after every use which will provide info for
maintenance and repair.
 Each centrifuge has a log book as the following.
 Return the clean (have to clean if spillage has occurred)
rotors to their location.

24. Rotor Sterilization and Disinfection
 Autoclave the rotor (and/or buckets) upside-down for up
to an hour (O-ring and gaskets can be left in place on
the rotor) if necessary.
 70% ethanol may be used on all rotor components.
If Spillage Has Occurred
 Wash the rotor and rotor components
immediately with cleaning kit.
 Beckman Solution 555
 Plastic coated brushes
 If radioactive, toxic or pathogenic
materials are involved, please contact
Tech Support Team.
 Please never leave unclean rotor to dry out which will
 damage the rotor
 make it very difficult for subsequent users.

25. Operating Procedures
 Sign up for it on website and log in on the log book.
 Turn on the centrifuge.
 Set up the parameters, speed, time, temperature, accelerate and
decelerate speed.
 Open the centrifuge door.
 Install the rotors with O-ring that contain balanced bottles or tubes.
 Make sure the rotor is properly seated to the drive hub.
 Secure the rotor with lid, close the centrifuge door.
 Press enter then run/start.
 Wait until reaching desired speed.
 After completely stopped, open the door and take out the sample
bottles or tubes, check whether spilling was happened or not, if
there is spill, take out the rotor, wash and dry it and return to its
storage place; never leave rotor inside the centrifuge; also clean the
chamber.
 Leave the high speed centrifuge door open and ultra speed
centrifuge door close and turn off the machine.

26. Care of Centrifuges and Rotors
 Carefully read the operating manual or receive proper instructions
before use any centrifuge.
 Select the proper operating conditions on the instrument.
 Check the rotor chamber for cleanliness and for damage.
 Select the proper rotor. Many sizes and types are available.
 Be sure the rotor is clean and undamaged.
 Filled centrifuge tubes or bottles should be weighed carefully and
balanced before centrifugation.
 Rotor manufactures provide a max. allowable speed limit for each
rotor. Do nor exceed that limit.
 Keep an accurate record of centrifuge and rotor use.
 If an unusual noise or vibration develops during centrifugation,
immediately turn the centrifuge off.
 Carefully clean the rotor chamber and rotor after centrifugation.

27. What happens to a particle in a centrifugal field
The particle (m) is acted on by three forces:
FC: the centrifugal force
FB: the buoyant force
Ff: the frictional force between the particle and the liquid
Equation that describes the motion of this particle as follows:
F = ma
where m is the mass of the particle and a is the acceleration.

28. The Physics of UltraCentrifugation
1.Centrifugal force:- The tube containing the suspension of particles is
rotated at a high speed, which exerts a centrifugal force directed from the center
of the rotor towards the bottom of the tube.
Centrifugal Force:
Where,
M: mass of particle
r: radius of rotation (cm) (ie distance of particle from axis of rotation)
ω :Average angular velocity (radians/sec)

29. Centrifugal field :- Depends on the radical distance of
the particle from the rotation axis and the square of the
angular velocity.
OR
Angular Velocity:- Detect to revolution per minute (r.p.m)

30. 2.Sedimentation rate:- This force acts on the suspended
particles pushing them towards the bottom of the tube at a rate
determined by the velocity of the spinning rotor.
Rate of Sedimentation:
Where,
r = radius at which the organelle is located
t = time
M = molecular weight
ν = partial specific volume of the molecule; inverse of the
density
ρ = density of the solvent
f = translational frictional coefficient
ω = angular velocity
NA = Avagadro’s number

31. 3.Sedimentation coefficient:- Centrifugation separates
particles in a suspension based on differences in size, shape and
density that together define their sedimentation coefficient.
Sedimentation Coefficient:
 This is know as the Svedberg equation and is usually expressed in
Svedberg units,
S (= second).
 This equation indicates that ‘S’ is dependent upon the molecular
weight, the density and the frictional coefficient.

32. Some High SpeedCentrifuges and Rotors

33. Some ultra SpeedCentrifuges and Rotors

34. Thank you