Gel documentation

Equipment widely used in molecular biology laboratories for the imaging

and documentation of various molecules such as nucleic acid and
protein suspended in agarose gels and polyacrylamide gels
Other name: Gel image system or Gel imager
The documentation means to record the image, from where the quality
and quantity of the biomolecules you are looking can be estimated.
For documentation , the biomolecule in the gel has to be stained with a
substance that when exposed to the light rays, the bound substance
flouresce that gives image of the biomolecule be visible.

For example: Ethidium bromide flouresce under ultra violet light, SYPRO
dyes or monobromobimane (MBB) are used to stain proteins.
 Components of gel documentation

• 1. Transilluminator
• 2. A hood to shield external light source
• 3. CCTV camera to capture the image
 Freeze dryer/Lypholizers
Expelling ice or other kinds of solidified solvents from an item
through the sublimation procedure and removing the bound
molecules of water through the desorption procedure is known as
Freeze Drying.
The controlled freeze drying maintain the temperature of the
product low enough during the procedure for avoiding
modifications in the dried item characteristics and appearance. This
is a marvellous technique for storing a large number of heat-
sensitive items like microbes, tissues, plasma, and proteins.
Is a low temperature dehydration process.
In freeze drying, it involves freezing the product, lowering pressure,
then removing the ice by sublimation. This is in contrast to
dehydration by most conventional methods that evaporate water
using heat.
 The Working Principle of Freeze drying

• Lyophilization is based on the principle of

sublimation. The process is performed at
temperature and pressure conditions below
the triple point to enable sublimation of ice.
The entire process is performed at low
temperature and pressure by applying
vacuum, hence it is suitable for drying of
thermo-labile compounds. The driving force is
the vapor pressure differences between the
evaporating surface and the condenser.
Equipment used for Lyophilization – LYOPHILIZER
A lyophilizer consists of
-A vacuum chamber containing product shelves
which are capable of cooling and heating containers and
their contents.
-A vacuum pump, a refrigeration unit, which is
associated controls are connected to the vacuum
chamber.
Samples are generally placed in containers such as glass
vials that are placed on the shelves within the vacuum
chamber.
Cooling elements within the shelves freeze the product.
Once the product is frozen, the vacuum pump evacuates
the chamber and the product is heated. Heat is transferred
by thermal conduction from the shelf, through the vial, and
ultimately into the product.
 A Lyophilizer’s 3 Primary Stages
Freezing Phase
A lyophilizer uses various methods to freeze the product. Freezing can be done
in a freezer, a chilled bath (shell freezer), or on a shelf in the lyophilizer. The
lyophilizer cools the material below its triple point to ensure that sublimation,
rather than melting, will occur. This preserves the material’s physical form.
However, with biological materials, when crystals are too large they may break
the cell walls, and that leads to less-than-ideal freeze drying results. To prevent
this, the freezing is done rapidly. For materials that tend to precipitate,
annealing can be used. This process involves fast freezing, then raising the
product temperature to allow the crystals to grow.
Primary Drying (Sublimation) Phase
A lyophilizer’s second phase is primary drying (sublimation), in which the
pressure is lowered and heat is added to the material in order for the water to
sublimate. The lyophilizer’s vacuum speeds sublimation. The lyophilizer’s cold
condenser provides a surface for the water vapor to adhere and solidify. The
condenser also protects the vacuum pump from the water vapor. About 95%
of the water in the material is removed in this phase. Primary drying can be a
slow process. Too much heat can alter the structure of the material.
• Secondary Drying (Adsorption) Phase
• A lyophilizer’s final phase is secondary drying (adsorption), during
which the ionically-bound water molecules are removed. By raising
the temperature higher than in the primary drying phase, the bonds
are broken between the material and the water molecules. Freeze
dried materials retain a porous structure. After the lyophilizer
completes its process, the vacuum can be broken with an inert gas
before the material is sealed. Most materials can be dried to 1-5%
residual moisture.
The process of freeze drying:

Freezing: product is frozen. This provide a necessary

condition for low temperature.
Vacuum: after freezing, the product is placed under
vacuum. This enables the frozen solvent in the product to
vaporize without passing through the liquid phase, a
process called sublimation.
Heat: heat is applied to the frozen product to accelerate
the sublimation.
Condensation: low-temperature condenser plates remove
the vaporized solvent from the vacuum chamber y
converting it back to a solid. This complete the process of
lyophilization.
 Objective of lyophilization
• To preserve the biological activity ofa product
• To reduce the product weight to lower the
transportation cost
• To extent the shelf life or stability
• To dry thermolabile materials
• To eliminate the need fro refrigerated storage
• To get accurate, sterile dosing into the final
product container.
 Advantages of the Lyophilization

• Lyophilization has many advantages over the other drying and

preserving techniques.
• It maintains food/ biochemical and chemical reagent quality
because they remains at a temperature that is below the freezing-
point during the process of sublimation. The use of lyophilization is
particularly important when processing lactic bacteria, because
these products are easily affected by heat.
• Food/biochemicals and chemical reagents which are lyophilized can
usually be stored without refrigeration, which results in a significant
reduction of storage and transportation costs.
• Lyophilization greatly reduces weight, and this makes the products
easier to transport. For example, many foods contain as much as
90% water. These foods are 10 times lighter after lyophilization.
• Because they are porous, most freeze-dried products can be easily
rehydrated. Lyophilization does not significantly reduce volume,
therefore water quickly regains its place in the molecular structure
of the food/ biochemicals and chemical reagents.