Review Article
ISSN: - 2306 – 6091
Available Online at: www.ijphr.com
An African Edge Journal
SJ Impact Factor
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5.546
NANOLIPOSOMES: TOOLS FOR TARGET DRUG DELIVERY SYSTEM
*1Anwesha Pattnaik,
2Ashok Kumar Panigrahi,
1Prasanta Kumar Biswal,
1Biswaranjan Ray
1
Gayatri College of Pharmacy, Sambalpur, Odisha, India.
2
Veer Surendra Sai Institute of Medical Sciences and Research, Burla, Sambalpur, Odisha, India.
___________________________________________________________________________
Abstract
Liposomes having sizes ranges from 10-9m are called nanoliposomes. Nanoliposomal drug system is a new technology for the encapsulation and delivery of bioactive agents and that possess significant role in drug formulation in order to improve the therapeutics activity. Nanoliposomes can be prepared by several methods like emulsion polymerization, microemlusion, membrane emulsification interface polymerization, ultrasonic technique, high pressure homogenization etc. In addition nanoliposomes posses various application in different diseases which includes asthma, grave’s disease, arthritis, treatment of respiratory and eye disorder, anticancer therapy, treatment of tuberculosis, use in skin disorder etc. Nanoliposomes have been used in food industry that is called food nanotechnology and that involves delivery of nutrients, flavours, nutraceuticals, enzymes, food additives and food antimicrobial. The present review or chapter discusses about preparation, mechanism, drug delivery system and application of nanoliposomes.
Keywords:
Nanoliposomes, Microencapsulation, Bioactive agent, Nanotechnology._________________________________________________________________________________________
Received on- 02.11.2018; Revised and accepted on- 09.11.2018; Available online- 17.11.2018
Introduction
Liposomes are composite structures made of
phospholipids and may contain small amounts of other molecules. Though liposomes can vary in size from low micrometer range to tens of micrometers, unilamillar liposomes are typically in the lower size range with various targeting ligands attached to their surface to allowing for their surface attachment and accumulation in pathological areas for treatments of disease.[1] A
liposomes is a spherical vesicle having atleast one lipid bilayer. The liposomes can be used as a vehicle for administration of nutrients and pharmaceuticals drug. Nanoliposomes having sizes ranges from 1/1000000000m.[2]
Classification of liposomes:
Depending upon their size and structures liposomes are classified as follows:- [3]
1. MLV (Multilamellar vesicles)-Having diameter of 5000nm
2. OLV (oligolamellar vesicles)-having a diameter of 100-1000nm
3. MVV (Multivesicular vesicles)-having diameter of more than 1000nm
4. ULV (Unilamellar vesicles)-These may be further classified on the basis of their size as below:
a. SUV (Small unilamellar vesicles)-having size 20-40nm
b. MUV (medium unilamellar vesicles)-size of 40-80nm
c. LUV (large unilamellar vesicles)-size of 100-1000nm
d. GUV (giant unilamellar vesicles)-size greater than 1000nm
Unilamellar
Multilamellar
Methods of liposome preparation:
General methods of preparation
All the methods of preparing the liposomes involve four basic stages:
1. Drying down lipids from organic solvent. 2. Dispersing the lipid in aqueous media. 3. Purifying the resultant liposome. 4. Analyzing the final product.
Method of liposome preparation and drug loading
The following methods are used for the preparation of Liposome:
1. Passive loading techniques 2. Active loading technique.
Passive loading techniques include three different methods:
1. Mechanical dispersion method. 2. Solvent dispersion method.
3. Detergent removal method (removal of non encapsulated Material).[4,5]
Mechanical dispersion method
The following are types of mechanical dispersion Methods:
1. Sonication.
2. French pressure cell: extrusion. 3. Freeze-thawed liposomes.
4. Lipid film hydration by hand shaking, non-hand shaking or freeze drying.
5. Micro-emulsification. 6. Membrane extrusion.
7. Dried reconstituted vesicles. [4,5]
Sonication:
Sonication is perhaps the most extensively used method for the preparation of SUV. Here, MLVs are sonicated either with a bath type sonicator or aprobe sonicator under a passive atmosphere. The main disadvantages of this method are very low internal volume/encapsulation efficacy, possible degradation of phospholipids and compounds to be encapsulated, elimination of large molecules, metal pollution from probe tip, and presence of MLV along with SUV.[4]
There are two sonication techniques:
a) Probe sonication: The tip of a sonicator is
directly engrossed into the liposome dispersion. The energy input into lipid dispersion is very high in this method. The coupling of energy at the tip results in local hotness; therefore, the vessel must be engrossed into a water/ice bath. Throughout the sonication up to 1 h, more than 5% of the lipids can be desterilized. Also, with the probe sonicator, titanium will slough off and pollute the solution.
b) Bath sonication. The liposome dispersion in a
cylinder is placed into a bath sonicator. Controlling the temperature of the lipid dispersion is usually easier in this method, in contrast to sonication by dispersal directly using the tip. The material being sonicated can be protected in a sterile vessel, dissimilar the probe units, or under an inert atmosphere. [6]
French pressure cell: Extrusion French pressure
cell involves the extrusion of MLV through a small orifice.[4] An important feature of the French press
vesicle method is that the proteins do not seem to be significantly pretentious during the procedure as they are in sonication.[7] An interesting comment is that French press vesicle appears to recall entrapped solutes significantly longer than SUVs do, produced by sonication or detergent removal. [8-10. The method involves gentle handling of unstable
difficult to attain, and the working volumes are comparatively small (about 50 mL as the maximum).[4,5] Freeze-thawed liposomes SUVs are
rapidly frozen and thawed slowly. The short-lived sonication disperses aggregated materials to LUV. The creation of unilamellar vesicles is as a result of the fusion of SUV throughout the processes of freezing and thawing [12-14]. This type of synthesis is
strongly inhibited by increasing the phospholipids concentration and by increasing the ionic strength of the medium. The encapsulation efficacies from 20% to 30% were obtained. [12]
Solvent dispersion method
Ether injection (solvent vaporization)
A solution of lipids dissolved in diethyl ether or ether-methanol mixture is gradually injected to an aqueous solution of the material to be encapsulated at 55°C to 65°C or under reduced pressure. The consequent removal of ether under vacuum leads to the creation of liposomes. The main disadvantages of the technique are that the population is heterogeneous (70 to 200 nm) and the exposure of compounds to be encapsulated to organic solvents at high temperature. [15,16]
Ethanol injection
A lipid solution of ethanol is rapidly injected to a huge excess of buffer. The MLVs are at once formed. The disadvantages of the method are that the population is heterogeneous (30 to 110 nm),liposomes are very dilute, the removal all ethanol is difficult because it forms into zoetrope with and the probability of the various biologically
active macromolecules to inactivate in the presence of even low amounts of ethanol is high.[17]
Detergent removal method (removal of non-encapsulated material)
Dialysis:
The detergents at their critical micelle concentrations (CMC) have been used to solubilise lipids. As the detergent is detached, the micelles become increasingly better-off in phospholipids and lastly combine to form LUVs. The detergents were removed by dialysis [18-20]. A commercial device called LipoPrep (Diachema AG, Switzerland), which is a version of dialysis system, is obtainable for the elimination of detergents. The dialysis can be performed in dialysis bags engrossed in large detergent free buffers (equilibrium dialysis).
Detergent (cholate, alkyl glycoside, Triton X-100) removal of mixed micelles (absorption)
Detergent absorption is attained by shaking mixed micelle solution with beaded organic polystyrene absorbers such as XAD-2 beads (SERVA Electrophoresis GmbH, Heidelberg, Germany) and Bio-beads SM2 (Bio-Rad Laboratories, Inc., Hercules, USA). The great benefit of using detergent absorbers is that they can eliminate detergents with a very low CMC, which are not entirely depleted.
Method of preparation of nano liposome encapsulated protein and protein encapsulated nanoliposome
The steps involved in the method of preparing nanoliposomes encapsulated protein are:
(a) Preparing dispersion by dispersing a phospholipid in an aqueous solution containing the protein;
(b) Applying a shearing force to the dispersion; (c) adding an additional amount of the phospholipids to the resultant of the step (b) and then applying a shearing force higher than that of the step (b) and;
d) Repeating the step (c) with an additional amount of the phospholipids and a shearing force higher than a prior step to obtain the nanoliposomes having a diameter and an encapsulation efficiency of interest, and a protein- encapsulating nanoliposomes.
A number of procedures have been established to produce well-defined liposomes:
Emulsion method:
Emulsification is a method preparing nanomedicine in emulsion. Commonly, versatile surfactants are used to form small drops of oil-in-water or water-in-oil under strong stirring
Emulsion polymerization
This method is usually used to prepare nanometer or micrometer polymer particles. The nucleus formation mechanism is a non-continuous process. The number of nuclei does not increase during the growing phase, while the sizes keep on growing. So the products diameter always ranges from 100 nm to several micrometers.
The self assembly in emulsion:
Amphipathic polymers are dissolved in organic solvent, and added in aqueous solution. Thereafter, an oil-in-water emulsion is formed. Then, a decompression distillation manipulation is preceded to remove the solvent and a micelle-like core-shell structure is formed in which the hydrophobic group is the core as the hydrophilic group extends into the outer aqueous phase forming the shell.
Membrane emulsification interface polymerization:
monodisperse functional microspheres and microcapsules. This method in the preparation of monodisperse drug carrier microsphere and microcapsule was introduced.
Microemulsion:
Microemulsion is colloidal thermodynamically stable nanodispersion of oil in water (or water in oil) stabilized by an interfacial film of surfactant and co-surfactant. It is widely used in the preparation of inorganic materials .Recently, the utility of microemulsions in the synthesis of biomedical important inorganic materials like hydroxyapatite has been investigated and also, its application has been found in many other aspects of nanomedicine.
Zhi et al in situ prepared magnetic chitosan/Fe3O4 composite nanoparticles in the tiny water pools of water-in-oil microemulsion containing chitosan and ferrous salt as microreactors by adding the basic precipitant of NaOH into the microemulsion. The chitosan particle size varied from 10 nm to 80 nm with good stability. Microemulsion were also used in the preparation of solid lipid nanoparticles, poor soluble drug nanoparticles and polymer nanospheres, etc.[21]
Ultrasonic technology:
Ultrasonic has great energy, which can even change the space between aqueous molecules and form little gas bubbles. Then gas bubbles keep on being formed and collapsed, which can cause ultrahigh temperature and pressure at local place (ultrasonic cavitation). Ultrasonic cavitation can provide a special physical chemical condition to initiate special reactions without catalyst . Wang et al used the ultrasonic emulsification crosslinking method to prepare mitomycin-loaded albumin nanospheres with a diameter between 60 and 100 nm. Ultrasonic technology was used as a dispersion method[22].
Solvent-Nonsolvent method
The solution of drug and/or the carrier materials is prepared firstly in this method. Then the solvent is removed via diafiltration or an evaporation procedure after dispersion in its nonsolvent. Particles will be formed because of the lack of solvent. The nanoparticles had spherical shapes and smooth surface. The size of nanoparticles was controlled by the amount of PEI, which acted as a hydrophilic moiety and reduced the interfacial
energy between the particle surface and the aqueous media. The nanoparticles showed an excellent dispersive stability under storage in a phosphate-buffered saline solution for 12 days.
High-pressure homogenization:
Date et al have successfully introduced this technology. During homogenization, the fracture of drug particles is brought about by cavitation, high shear forces and the collision of the particles against each other. The drug suspension contained in a cylinder of diameter about 3 mm passes suddenly through a very narrow homogenization gap of size 25 ¦Ìm which leads to high streaming velocity. In the homogenization gap, according to Bernoulli's equation, the dynamic pressure of the fluid increases with the simultaneous decrease in static pressure below the boiling point of the water at room temperature. In consequence, water starts boiling at the room temperature leading to the formation of gas bubbles, which implode when the suspension leaves the gap (called as cavitation) forcing the drug particle to crash into nanoscale pieces.
Mechanism of action of nanoliposomes[23]
second agent. The agent in the outer lipid compartment is released first and may exert its effect before the agent in the nanocore is released. The nanocell delivery system may be formulated in pharmaceutical composition for delivery to patients suffering from diseases such as cancer, inflammatory diseases such as asthma, autoimmune diseases such as rheumatoid arthritis, infectious diseases, and neurological diseases such as epilepsy. In treating cancer, a traditional antineoplastic agent is contained in the outer lipid vesicle of the nanocell, and an antiangiogenic agent is loaded into the nanocore. This arrangement allows the antineoplastic agent to be released first and delivered to the tumor before the tumor's blood supply is cut off by the antianiogenic agent.
Nano liposomes are used in the treatment of diseases like:
1. Asthma 2. Cancer 3. Arthritis 4. Psoriasis
5. Multiple sclerosis 6. Sports injuries 7. Brain tumour 8. Grave’s disease 9. Cystic fibrosis
10. Pulmonary fibrosis
Targeting agents:
The targeting agents may be included throughout the nanocells, only in the inner nanocore, only in the outer lipid or polymeric shell portion, or may be only on the surface of the nanocell. The targeting agent may be a protein, peptide, carbohydrate, glycoprotein, lipid, small molecule, metal, etc. The targeting agent may be used to target specific cells or tissues or may be used to promote endocytosis or phagocytosis of the particle. Examples of targeting agents include, but are not limited to, antibodies, fragments of antibodies, low-density lipoproteins (LDLs), transferrin, asialycoproteins, gpl20 envelope protein of the human immunodeficiency virus (HIV), carbohydrates, receptor ligands, sialic acid, etc. If the targeting agent is included in the nanocore, the targeting agent may be included in the mixture that is used to form the nanoparticles. If the targeting agent is only on the surface of the nanocells, the targeting agent may be associated with (i.e., by covalent, hydrophobic, hydrogen boding, van der Waals, or other interactions) the formed particles using standard chemical techniques.
The methods and drug delivery routes of pharmaceuticals are very important for a good therapeutic effect. Oral drug delivery is strongly affected by the first pass effect, which includes the degradation and metabolism of the enzymes which come from the stomach, intestine, and liver. A large part of the drug is degraded because of the first pass effect, especially for the peptides and protein. The targeted delivery is also affected by the structure of the apparatus and groups of human body, for example, the immunity system, the reticulo endothelial system, the blood brain barrier, etc.. Nanomedicine is a combination of tradition pharmacy, pharmacology, medicine and modern nanometer technology. According to the National Institutes of Health in America, nanomedicine is referred to the application of nanometer technology for treatment, diagnosis, monitoring, and control of biological systems. The forefront problems of nanomedicine mostly focus on their rational delivery routes and targeting ability, which includes the accurate recognition of specific clinic pathological sites, and to choose appropriate drug carrier to meet given requirements and minimize the side effects at the same time. Parenteral routes i.e. intravenous, intramuscular or subcutaneous routes are used for drug-administration. Liposomes are the nanosystems that are administered intravenously. Other nanoscale drug carriers have a high ability for improving the drug-delivery through nasal and sublingual routes thus avoiding the initial metabolism and accessing otherwise directly inaccessible area like brain and intra-articular cavities. The nasal route is now being used to administer the drug molecules with nanoparticles thus greatly improving the bioavailability of drugs.Now a day pulmonary problem is increasing, they account for more than one third of the drug delivery market. Nanotechnology is now being used to make drug delivery efficient in the lungs. The drugs are delivered via various ways inhaler systems, aerosols, powder/capsule inhalers and nebulizers, which are now revised to contain nanostructures like dendrimers, micelles, nanoparticles and liposomes. This route forms an effective route for delivering protein and peptide drugs. Transdermal drug delivery is another research field for nano delivery systems. It avoids troubles of gastrointestinal problems and the drug degeneration. Moreover, due to minimal meddling caused by the presence of food, the drug-delivery rate becomes more efficient. Moreover this
procedure is non-invasive and is used for local drug delivery. Trans-tissue drug delivery systems are also becoming popular and need to be adhered to the resected tissue during surgery.
The materials and types of nanoliposomal carriers [24]
The drug carriers of nanomedicine are extremely important in the treatment of many diseases. There are many kinds of natural macromolecules that can be used as materials to produce nanomedicine, such as chitosan, gelatin, alginate, starch, cellulose, albumin and their derivatives, etc. Most of them have the merits of perfect biodegradability and biocompatibility. But their application in nanomedicine is largely restricted by the lack of uniform structure, which is coursed by the difference of their origin, material, and even the producing procedure. Moreover, nature materials are difficult to modify to meet different cases. In order to conquer these problems, more and more biodegradable and biocompatible synthetic materials appeared, most of which are polymer. These manmade polymers involve polyester, polyanhydride, poly ortho ester, polyamide, and their copolymers.
The type of carriers are as follows:
The type of carriers includes macromolecules and particulates. The macromolecules include polymer, dendrimer, monoclonal antibody (MAB), etc. Most of the macromolecules carriers need covalent conjugation of the drug to prevent it from enzymatic degradation
Uses of nanoliposomal drug delivery systems
1. Ophthalmic uses
increase the solubility of the drug in solution and to increase corneal permeability. Finally, collagen shields have been developed as a new continuous-delivery system for drugs that provide high and sustained levels of drugs to the cornea, despite a problem of tolerance.
2. Administering antifungal agents
The antifungal agents for systemic mycoses are only a few in numbers. Among them amphotericin-B is still the most widely used drug. In Japan, studies on efficacies of lipid nanosphere-encapsulated AMPH-B are in progress. Special drug career systems and dosage forms, such as nanoparticles and liposomes hold the promise of overcoming the pharmacokinetic limitations. Nanoparticles are stable, solid colloidal particles consisting of macromolecular material and vary in size. Nanoparticles represent an interesting carrier system for the specific enrichment in macrophage containing organs like liver and spleen. Injectable nanoparticle carriers have important potential applications as in sitespecific drug delivery. Modifications of liposomes in order to avoid uptake by RES, thus increase target ability has been attempted. A novel targetable liposome 34A-PEG-L modified with polyethylene glycol conjugated with MoAb, 34A specific to murine pulmonary
epithelia has been evaluated in murine pulmonary aspergillosis. 34A-PEG-L-AmB showed higher tissue concentration and comparable efficacy than other AMPH-B formulations
3. Anticancerdrugs[25]
Anthracyclines are drugs which stop the growth of dividing cells by intercalating into the DNA and, thus, kill mainly rapidly dividing cells. These cells are not only in tumours but are also in hair, gastrointestinal mucosa, and blood cells; therefore, this class of drug is very toxic. The most used and studied is Adriamycin (commercial name for doxorubicin HCl; Ben Venue Laboratories, Bedford, Ohio). In addition to the above-mentioned acute toxicities, its dosage is limited by its increasing cardio toxicity. Numerous diverse formulations were tried. In most cases, the toxicity was reduced to about 50%. These include both acute and chronic toxicities because liposome encapsulation reduces the delivery of the drug molecules towards those tissues. For the same reason, the efficiency was in many cases compromised due to the reduced bioavailability of the drug, especially if the tumour was not phagocytic or located in the organs of mononuclear phagocytic system.
4. Use in skin care
Cosmeceuticals and natural skincare by elsom research are active nano-topicals formulated with
vitamins, actives and other natural ingredients. Cosmeceuticals undergo enhanced formulation with our nano-technology systems. We also creatively combine traditional botanicals and formulation with our state-of-the-art
Nano-encapsulation of actives can improve their
function, increase the range of their activity, reduce the concentration of use, increase shelf life, reduce color and odor of actives, protect the active from rapid degradation and protect the skin from prolonged exposure to actives.
Nano-emulsion creates a large surface-to-volume
ratio for emulsion particles that contact skin, so more active ingredients contact the skin at the surface-to-surface interaction between the emulsion and the skin.
Nanosomes (nano-liposomes) can act as both
encapsulation and delivery systems. Nanosome-derived technologies revitalize the field of liposome technology with new and exciting applications. Intra-Dermal and
Trans-Dermal Vehicles have been developed for
topical use. These vehicles are suitable for delivery via skin of actives and drugs in cosmetic and OTC applications.
5. Use in treatment of tuberculosis[26]
Rifampicin and Isoniazid liposomes prepared out of physiological lipids have proved to be of great use in the treatment of tuberculosis. These liposomes were modified so as to reduce their non-specific uptake by the reticuloendothelial system and to make them lung specific .The preparations were stable, nontoxicand a single intravenous (i.v.)administration produced therapeutic plasma/tissue drug levels for 5 – 7 days. Further, weeklytherapy for six weeks led to a significant reduction in mycobacterial counts in M.tuberculosis infected mice. Keeping in mind that pulmonary TB is the commonest form of TB andalveolar macrophages are the abode of M.tuberculosis, the administration of Aziothymidinevia therespiratory route is an exciting possibility.
6. Nano-particles with contrast agents for diagnostic delivery system for X-ray and CT: Liposomes (microscopic artificial phospholipids vesicles) and micelles (amphiphilic compound colloidal particles with lipophilic cores and hydrophilic coronas) are preferred as contrast agent encapsulating carriers because of their easily controlled properties and good pharmacological characteristics (excellent biocompatibility and biodegradability). For specific in vivo delivery, the
sizes, charges, and surface properties of these carriers can be easily changed by adding new ingredients to the lipids or amphiphilic compound mixtures before the liposomes or micelles are prepared, and by varying the preparation methods. The ability of liposomes to entrap different substances into the aqueous phase and the membrane compartment makes them suitable for carrying the diagnostic contrast agents used with different imaging techniques. The varying chemical properties of contrast compounds require specific protocols for loading the liposomes. In addition, the imaging techniques differ not only in their sensitivity and resolution, but also in the amounts of diagnostic labels to be delivered into the an organ. When phospholipid liposomes are introduced into the circulatory system, they are rapidly sequestered by the cells of the reticuloendothelial system (RES) (half-clearance time <30 min). Liver cells are primarily responsible for absorbing the liposomes in the areas of interest.
7. Administration of vit-C
Lypo-Spheric Vitamin C has been used widely for administering Vit C.
These are widely used because
- Quickly navigate through the digestive system. - Eliminate need for digestive activity prior to assimilation.
- Rapidly absorb in the small intestine and move intact directly to the cells that need it.
- Release the powerful, non-degraded Vitamin C for use throughout the body as the liposomal material is assimilated by the phospholipids-craving cells that are under attack.
- Provide maximum assimilation and bio-availability.
8. Other uses:
antimicrobials that could aid in the protection of food products against microbial contamination. In this paper, the main physicochemical properties of liposomes and nanoliposomes are described and some of the industrially applicable methods for their manufacture are reviewed. A summary of the application of nanoliposomes as carrier vehicles of nutrients, nutraceuticals, enzymes, food additives, and food antimicrobials is also presented.
Adverse efects [27]
Toxicity of nanoliposomes:
Submicron lipid vesicles (nanoliposomes) are being used as carriers of bioactive compounds. In addition, complexes of nanoliposomes and nucleic acids (nanolipoplexes) are promising tools for the treatment of cancer, and viral and genetic disorders. Toxicity of some of these formulations, however, still remains a concern in their clinical utilization. To address this problem, anionic liposomes were prepared by two different techniques, the conventional thin-film method, and the heating method (HM), in which no volatile organic solvent or detergent is used. An anionic nanolipoplex was constructed by incorporating plasmid DNA into the HM-nanoliposomes by the mediation of calcium. The toxicity of the nanoliposomes, with and without plasmid and Ca2+, was assessed using a
human bronchial epithelial cell line (16HBE14o-) in the presence of serum. Cytotoxicity evaluations performed by two different assays (i.e. NRU and MTT) indicated that HM-nanoliposomes were completely non-toxic in the cell-line tested, whereas conventional liposomes revealed significant levels of toxicity. This may be due to the presence of trace amounts of chloroform and/or methanol applied during their preparation. Similar results were obtained for different sizes of lipid vesicles (prepared by 100 nm and 400 nm pore-size filters). In addition, it was observed that incorporation of DNA (15 μg/285 μg lipid) and Ca2+ (50 mM) to the nanoliposomes did not have
any effect on their cytotoxicitiesnanomedicine has brought us many problems because of its ability in changing the pharmacokinetics, which is called nanotoxicity. Some forefront problems are the distribution, degradation and release process as well as the therapeutic mechanism of nanomedicine and its influences on human function and metabolism
Conclusion:
Nanoliposomes are good enough to carry the drug. This form of drug designing is superior having less disadvantages. In concern to Bioavailability it has many advantages. Drug reaches to target site more prominently. More manufacturing technology and deep study need to carry on this pattern of drug delivery.
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