Polyacrylamide Gel Electrophoresis: Advantages and Disadvantages

Polyacrylamide Gel Electrophoresis: Advantages and Disadvantages

You must have known that agarose gel electrophoresis is generally adequate for resolving nucleic acid fragments in the size range of 100 nucleotides to around 10-15 kb. But, for nucleic acid which its fragments below those range, it will be difficult to separate and hard to visualize because of diffusion within the gel matrix. These problems are solved by native polyacrylamide gel electrophoresis (PAGE). Using native PAGE, fragments as small as 10 bp and up to 1 kb can be separated with a resolution of as little as 1 bp.

Polyacrylamide Gel Electrophoresis has a number of advantages, which are:

  • PAGE has a high loading capacity, up to 10 micrograms of DNA can be loaded into a single well (1 cm x 1 mm) without significant loss of resolution.
  • Polyacrylamide contains few inhibitors of enzymatic reactions.
  • PAGE is an ideal gel system from which to isolate DNA fragments for subcloning and other molecular biological techniques.

As any other methods, PAGE also has disadvantages:

  • The mobility of the fragments can be affected by base composition making accurate sizing of bands a problem.
  • Polyacrylamide quenches fluorescence, making bands containing less than 25 ng difficult to visualize with ethidium bromide staining.

The methods to separate and to purify DNA fragments will be described later in the next post.

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Advantages and application of the Fas gel

Article Summary:

The process of agarose gel electrophoresis is the most common method in which DNA molecule is separated and analyzed. This method is commonly used in the field pf biochemistry and molecular biology for the isolation of DNA. This technique also supports the separation and analysis of proteins. A chemical ethidium bromide is used to visualize the DNA molecule. The property of this chemical is that it binds to the DNA bases strongly and makes it visualized.

Process of Gel electrophoresis:-
The process of gel electrophoresis for the separation of DNA molecules takes place in the following manner:-
1) Using the restriction enzymes, DNA molecule is cut into small pieces or fragments.

2) The cut DNA fragments are moved to the wells or pots where agarose gel is already present.

3) The agarose gel along with the DNA fragments is passed through an electric current.

4) The well is equipped with negatively and positively charged electrodes. When electric current is released in the gel, the negative electrode repels the negatively charged DNA fragments and they move to the positive pole of well.

5) Through this method DNA fragments can be isolated according to their size and they can easily be visualized.

Applications of Agarose Gel:-
The main purpose of agarose gel is to isolate and analyze the DNA molecules which are cut by restriction enzymes. These cut pieces of DNA can be used for the cloning purpose to make various plasmids from one fragment. The function of gel electrophoresis is to isolate cut plasmids or vectors from the uncut vectors.

Agarose gel can also be used to separate the RNA or protein molecules from the gel. DNA fragments re separated before Southern blotting and RNA and proteins are separated before the Northern blotting. It also allows the DNA fragments to pass through PCR to make various copies of DNA molecules, so that they can be used in DNA fingerprinting or in any other method. DNA molecules of same size can be isolated through the agarose gel, when the electric current is passed through it.

Quantity and quality of the size of DNA molecule is analyzed by lambda DNA ladder and by observing the absence of streaking of fragments respectively. It means that only those DNA fragments can be observed or isolated which have fluorescent streak in them so that they can be identified.

Advantages and Disadvantages:-
The main benefit of agarose gel technique is that it can be easily processed and the DNA molecule that is used as a sample can also be recovered without any harm to it at the end of the process. Agarose gel does not denature the DNA samples and they stay in their own from.

There is also a disadvantage of gel electrophoresis that it may melt when the electric current is passed through it. Due to this reason there are chances that genetic material can adopt the shapes which are not needed.

Use of Gel Electrophoresis:-
Gel electrophoresis can be used the field of forensics. The process of DNA fingerprinting can be performed using the agarose gel DNA electrophoresis.

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Advantages And Disadvantages Of Gel Nails

When gel nails appeared for the first time, the industry changed completely. Gel on nails became one of the best inventions that appeared in the field of manicure. Slowly, a lot of women went from classic manicures to gel nails because of the advantages of them. Probably a lot of you are familiar with the procedure, but for the ones who are not, we will explain what gel nails are. Gel nails are basically extensions made using a hard gel product that is even more hardened under an ultraviolet or L.E.D. (light emitting diode) light. The gel is designed to imitate how natural nails look. They are designed to last much longer and give women who have short nails, the opportunity to wear long nails without being afraid of common breaking from various reasons (natural nail is more prone to breakage and the structure of it is more sensitive). Probably you wonder what are the advantages of having them and of course if there are any sort of disadvantages too. We will elucidate the mystery in this article.

Advantages of gel nails:
1. They last longer for about 3 to 4 weeks, which is awesome compared to a classic nail polish that usually lasts 3 to 4 days, no?
2. They dry instantly while you are still in the salon, no need to worry. So, no smearing, no chipping, no smudging or scratching off
3. Gel nails allow the person to experiment fabulous nail designs as they are easier to work with and create designs that with normal nail polish you can not acquire.
4. The gel looks fresh all the time that it is on your nails, even before you go and take it off.
5. The gel is the most close option to natural looking nails, even if you want a french manicure!

Disadvantages of gel nails:
1. Nails might get a little more irritable from the procedure as they are buffed to remove their natural shine so the gel stick better to them. In time, your nails can become thinner.
2. The removal of them is a little harmful as you need to soak them in pure acetone which will dry the fingers a lot.
3. Sometimes, from wrong procedures, you might get some infections (rare cases, but risks are still there).
4. Risk of nail breakage as the nail breaks at a much higher point (if that ever happens).
5. If you want to go back to classic nail polish, specialists say your nails need 6 weeks to recover completely.

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What Are the Benefits of Hair Gel?

Hair gel is a popular product for controlling a person’s hair and maintaining the look she wants. However, not all hair gels are the same, and different varieties will offer different results. Organic hair gels may work best for delivering nutrients to your scalp, whereas more synthetic hair gels may offer styles that wouldn’t be possible without a strong hold. What benefits a person gets from hair gel will depend on what gel she uses and what that gel is formulated to do.

Control

The main benefit of using hair gel in the first place is that it gives you control over your hair and your hairstyle. Whether you’re putting your hair up into foot-long Liberty spikes (only the toughest hair gels will allow you to get away with this) or you just want to maintain a loose, fresh-out-of-the-shower look, the proper hair gel will allow you that sort of control. Without gel, your hair will dry and do whatever it would naturally do; whether that’s curl, frizz or just hang limply depends on the person. The proper gels open up the field and let people access different styles.

Nutrients

Some hair gels, particularly those that are organic, may offer benefits beyond strong hold and an attractive look. These hair gels can be fused with organic herbs that will soak into both your scalp and your hair, providing both with nutrients that they may not be getting either because of too much exposure to chemicals or because you just aren’t getting those particular vitamins in your diet. These gels may be of a particular help to those who have dry scalp or lank hair that could use some nutritional infusion.

Color

There are some hair gels that also offer temporary color. These are mostly used for parties, concerts or other similar events since the color that they provide is both temporary and not as natural looking as genuine hair dyes might be. However, for those who may not be able to dye their hair permanently due to professional obligations, or for those who are curious what they’d look like with different color hair before they try a more permanent option, these gels may be a way of finding out. They work as a try-before-you-buy option.

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PHARMACEUTICAL GELS: IN SUMMARIZED FORM

About Author:
Piyush Tripathi
Kota College of Pharmacy,
Kota (RAJ)
[email protected]

Definition:
A gel is a solid or semisolid system of at least two constituents, consisting of a condensed mass enclosing and interpenetrated by a liquid 4 .

Advantages 5,6,7 :

  • Gels are used to achieve optimal cutaneous and percutaneous drug delivery.
  • They can avoid gastrointestinal drug absorption difficulties caused by gastrointestinal pH.
  • Gels are having property to avoid enzymatic activity and drug interaction with food and drinks.
  • They can substitute for oral administration of medication when the route is unsuitable.
  • They can avoid the first pass effect, that is, the initial pass of drug substance through the human body.
  • They avoid systemic and portal circulation following gastrointestinal absorption.
  • Gels are not deactivated by liver enzymes because the liver is bypassed.
  • They are non-invasive and have patient compliance.
  • They are applied over skin for slow and prolonged absorption.
  • Gels have also been applied in pharmacy to some viscous suspension for oral use for example Aluminium hydroxide gel.
  • They have localized effect with minimum side effects.

REFERENCE ID: PHARMATUTOR-ART-1871

Disadvantages 6,8,9 :

  • Gels have possibility of allergenic reactions.
  • Enzyme in epidermis may denature the drugs of gels.
  • Drugs of larger particle size do not absorb through the skin.
  • They have poor permeability of some drugs through the skin.
  • Selection of area to be examined carefully during application of gels.
  • Gels which are used for the introduction into body cavity or the eyes should be sterilized.
  • They may causes application side reactions.
  • They may cause skin allergy during application.

DELIVERY THROUGH SKIN
Delivery of drugs to the skin is an effective and targeted therapy for local dermatological disorders. Topical gel formulations provide a suitable delivery system for drugs because they are less greasy and can be easily removed from the skin 10 .

Fig: Longitudinal section showing layers of skin

Advantages of This Route 6 ,16 :

  • It provides a largest surface area.
  • It avoids first-pass effects, gastrointestinal irritation.
  • It avoid metabolic degradation associated with oral administration.

Mechanism of Drug Absorption 19 :
The principal mechanisms of drug absorption are:
1.Passive diffusion
2.Pore transport
3.Facilitated diffusion
4.Active transport
5.Ionic or electrochemical diffusion
6.Ion-pair transport
7.Endocytosis

Physiological Factors Affecting Skin Penetration 13,21 :
1. Skin integrity
2. Skin hydration
3. Skin temperature
4. Regional variation
5. Traumatic/pathologic injury to skin
6. Cutaneous drug metabolism

Formulation Factors Affecting Skin Penetration 13,21,22 :

1. Penetration enhancer.
2. Occlusivity
3. Drug concentration
4. pH
5. Solubility
6. Surfactant

CLASSIFICATION

Classification of Gels is Following:
A. Controlled release gels
B. Organogels
C. Extended release gels
D. Amphiphilic gels
E. Hydrophilic gels
F. Non aqueous gels
G. Bioadhesive gels
H. Thermosensitive sol-gel reversible hydrogels
I. Complexation gels
J. Hydrogel

A. Controlled Release Gels :
Drug delivery to nasal or ocular mucosa for either local or systemic action suffers from many obstacles. Gel formulations with suitable rheological and mucoadhesive properties increase the contact time at the site of absorption. However, drug release from the gel must be sustained if benefits are to be gained from the prolonged contact time.

These gels were formed in simulated tear fluid at concentrations of polymer as low as 0.1%, and it was shown that sodium was the most important gel-promoting ion in vivo. Rheology, although it may be a questionable technique for evaluating mucoadhesive properties of polymers, showed that interactions between mucin and polymers were most likely to be seen with weak gels.

B. Organogels :
Sorbitan monostearate, a hydrophobic nonionic surfactant, and numbers of organic solvents such as hexadecane, isopropyl myristate, and a range of vegetable oils are present. Gelation is achieved by dissolving/dispersing the organogelator in hot solvent to produce an organic solution/dispersion, which, on cooling sets to the gel state.

Such organogels are affected by the presence of additives such as the hydrophilic surfactant, polysorbate 20, which improves gel stability and alters the gel microstructure from a network of individual tubules to star-shaped «clusters» of tubules in the liquid continuous phase. Another solid monoester in the sorbitan ester family, sorbitan monopalmitate, also gels organic solvents to give opaque, thermoreversible semisolids. Like sorbitan monostearate gels, the microstructure of the palmitate gels comprises an interconnected network of rod like tubules.

C. Extended Release Gels:
It is a controlled release technology consists of an agglomerated, hydrophilic complex that, when compressed, forms a controlled-release matrix. It consisting of xanthan and locust bean gums (two polysaccharides) combined with dextrose surrounds a drug core. In the presence of water, interactions between the matrix components form a tight gel while the inner core remains unwetted.

The drug is encapsulated in the pores of the gel, and as the matrix travels through the patient’s digestive system, the tablet swells and begins to erode. This erosion allows the drug to “back-diffuse” out through the gel-matrix at a controlled rate until the matrix erodes and a majority of the drug is released. The fundamental component controlling the rate of release lies in the properties of the gel matrix.

D. Amphiphilic Gels :
Amphiphilic gels can prepared by mixing the solid gelator like sorbitan monostearate or sorbitan monopalmitate and the liquid phase like liquid sorbitan esters or polysorbate and heating them at 60°C to form a clear isotropic sol phase, and cooling the sol phase to form an opaque semisolid at room temperature.

Amphiphilic gel microstructures consisted mainly of clusters of tubules of gelator molecules that had aggregated upon cooling of the sol phase, forming a 3D network throughout the continuous phase. The gels demonstrated thermoreversibility. Gelation temperature and viscosity increased with increasing gelator concentration, indicating a more robust gel network. At temperatures near the skin surface temperature, the gels softened considerably, this would allow topical application.

E. Hydrophilic Gels :
Hydrophilic gels are composed of the internal phase made of a polymer producing a coherent three-dimensional net-like structure, which fixes the liquid vehicle as the external phase. Intermolecular forces bind the molecules of the solvent to a polymeric net, thus decreasing the mobility of these molecules and producing a structured system with increased viscosity.

F. Non Aqueous Gels :
Ethylcellulose was successfully formulated as a nonaqueous gel with propylene glycol dicaprylate/dicaprate. The novel nonaqueous gel exhibited rheological profiles corresponding to a physically cross-linked three dimensional gel network, with suitable mechanical characteristics for use as a vehicle for topical drug delivery. Molecular conformation of the solvent was found to influence the molecular interactions associated with formation of ethylcellulose gel networks.

The gel matrices exhibited prominent viscoelastic behavior, yield stress and thixotropy. Rheological and mechanical properties showed significant upward trends with increased polymeric chain length and polymer concentrations. Good linear correlations were obtained between rheological and mechanical properties. The solvent molecular conformation was found to play a role in affecting the formation of gel networks via intermolecular hydrogen bonding between ethylcellulose polymer chains.

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Write down tire advantages and disadvantages of sol-gel technique.

Write down tire advantages and disadvantages of sol-gel technique.

Ans. Advantages

(i) As the process is based on chemical reactions in liquid phase, it is very simple technique.

(ii) It is also cost-effective, as very simple accessories are required for the chemical reaction and deposition procedures.

(iii) As the deposition is done in liquid phase, the process is versatile enough to produce a large form of materials starting from aerogel , xerogel, ceramic materials, micro-/nano-powders, nanostructured thin films, nano- · particles/nano-wires/nano-rods/nano-pillars, etc.

(iv) Due to the chemistry involved in the process, a large range of materials can be deposited by this procedure.

(v) Due to the liquid phase deposition, large and complex shaped substrates can also be coated by this process.

(vi) Possibility of high purity of starting material can also be achieved.

(vii) Precise control over the doping level is also easier in this process.

Disadvantages- The process is not very ‘clean’. As the process involves chemical reactions between several ingredients in solution, it contains undesired atoms, molecules, ions, etc., in the required material, which deteriorates the electrical as well as optical properties of the deposited material. Therefore, this technique is not compatible with the modern solid state device fabrication technique, which is the primary manufacturing process for electronic and photonic devices.

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Advantages and application of the Fas gel

To search by structure, left click in the box below to display the chemdraw toolbar. Then, draw the chemical structure of interest in the box using the toolbar. When your structure is complete, click “Search by Name” or “Search by SMILES” to generate the product name or SMILES respectively. This feature will search within the Gelest product database for matching chemical names or SMILES. Note: In cases where Gelest uses alternate chemical names, it may be necessary to search for the product of interest by its CAS#.

Sol Gel Applications

Gelest, Inc. offers a wide range of metal alkoxides for use in sol gel applications.

Sol gel is a method for preparing specialty metal oxide glasses and ceramics by hydrolyzing a chemical precursor or mixture of precursors that pass sequentially through a solution state and a gel state before being dehydrated to a glass or ceramic.

Sol Gel Process Technology and Chemistry (illustrated overleaf) Preparation of metal oxides using sol gel routes proceeds by three basic steps:

  1. partial hydrolysis of metal alkoxides to form reactive monomers,
  2. condensation of these monomers to form colloid-like oligomers (sol formation),
  3. additional hydrolysis to promote polymerization and cross-linking leading to a three-dimensional matrix (gel formation).

Sol gel technology can be used to prepare fibers, microspheres, thin films, fine powders and monoliths. Applications for sol gel technology include protective coatings, catalysts, piezoelectric devices, wave-guides, lenses, high-strength ceramics, superconductors, synthesis of nanoparticles and insulating materials. The flexibility of sol gel technology allows unique access to multi-component oxide systems and low temperature process regimens. Listed below are some popular examples of sol gel precursors, and Gelest, Inc. offers hundreds of other alkoxide derivatives for metals of interest.

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