Liposome
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A liposome is a small artificial vesicle, spherical in shape, having at least one
lipid bilayer The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes form a continuous barrier around all cell (biology), cells. The cell membranes of almost all organisms and many viruses a ...
. Due to their hydrophobicity and/or hydrophilicity, biocompatibility, particle size and many other properties, liposomes can be used as
drug delivery Drug delivery involves various methods and technologies designed to transport pharmaceutical compounds to their target sites helping therapeutic effect. It involves principles related to drug preparation, route of administration, site-specif ...
vehicles for
administration Administration may refer to: Management of organizations * Management, the act of directing people towards accomplishing a goal: the process of dealing with or controlling things or people. ** Administrative assistant, traditionally known as a se ...
of
pharmaceutical drug Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the ...
s and
nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
s, such as lipid nanoparticles in mRNA vaccines, and
DNA vaccines A DNA vaccine is a type of vaccine that transfection, transfects a specific antigen-coding DNA sequence into the cells of an organism as a mechanism to induce an immune response. DNA vaccines work by injecting genetically engineered plasmid con ...
. Liposomes can be prepared by disrupting biological membranes (such as by
sonication image:Sonicator.jpg, A sonicator at the Weizmann Institute of Science during sonicationSonication is the act of applying sound energy to agitate particles in a sample, for various purposes such as the extraction of multiple compounds from plants, ...
). Liposomes are most often composed of
phospholipid Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...
s, especially
phosphatidylcholine Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup. They are a major component of biological membranes and can easily be obtained from a variety of readily available sources, such as egg yolk or soyb ...
, and
cholesterol Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils. Cholesterol is biosynthesis, biosynthesized by all anima ...
, but may also include other lipids, such as those found in
egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...
and
phosphatidylethanolamine Phosphatidylethanolamine (PE) is a class of phospholipids found in biological membranes. They are synthesized by the addition of cytidine diphosphate-ethanolamine to diglycerides, releasing cytidine monophosphate. S-Adenosyl methionine, ''S''-Ade ...
, as long as they are compatible with
lipid bilayer The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes form a continuous barrier around all cell (biology), cells. The cell membranes of almost all organisms and many viruses a ...
structure. A liposome design may employ surface
ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...
s for attaching to desired cells or tissues. Based on vesicle structure, there are seven main categories for liposomes: multilamellar large (MLV), oligolamellar (OLV), small unilamellar (SUV), medium-sized unilamellar (MUV), large unilamellar (LUV), giant unilamellar (GUV) and multivesicular vesicles (MVV). The major types of liposomes are the multilamellar vesicle (MLV, with several lamellar phase
lipid bilayer The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes form a continuous barrier around all cell (biology), cells. The cell membranes of almost all organisms and many viruses a ...
s), the small
unilamellar liposome A unilamellar liposome is a spherical liposome, a vesicle, bounded by a single bilayer of an amphiphilic lipid or a mixture of such lipids, containing aqueous solution inside the chamber. Unilamellar liposomes are used to study biological system ...
vesicle (SUV, with one
lipid bilayer The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes form a continuous barrier around all cell (biology), cells. The cell membranes of almost all organisms and many viruses a ...
), the large unilamellar vesicle (LUV), and the cochleate vesicle. A less desirable form is multivesicular liposomes in which one vesicle contains one or more smaller vesicles. Liposomes should not be confused with
lysosome A lysosome () is a membrane-bound organelle that is found in all mammalian cells, with the exception of red blood cells (erythrocytes). There are normally hundreds of lysosomes in the cytosol, where they function as the cell’s degradation cent ...
s, or with
micelle A micelle () or micella () ( or micellae, respectively) is an aggregate (or supramolecular assembly) of surfactant amphipathic lipid molecules dispersed in a liquid, forming a colloidal suspension (also known as associated colloidal system). ...
s and reverse micelles.Stryer S. (1981) Biochemistry, 213 In contrast to liposomes, micelles typically contain a monolayer of fatty acids or surfactants.


Discovery

The word ''liposome'' derives from two Greek words: ''lipo'' ("fat") and ''soma'' ("body"); it is so named because its composition is primarily of phospholipid. Liposomes were first described by British hematologist Alec Douglas Bangham in 1961 at the Babraham Institute, in Cambridge—findings that were published 1964. The discovery came about when Bangham and R. W. Horne were testing the institute's new
electron microscope An electron microscope is a microscope that uses a beam of electrons as a source of illumination. It uses electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing it ...
by adding
negative stain In microscopy, negative staining is an established method, often used in diagnostic microscopy, for contrasting a thin specimen with an optically opaque fluid. In this technique, the background is stained, leaving the actual specimen untouched, ...
to dry phospholipids. The resemblance to the
plasmalemma The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the cytoplasm, interior of a Cell (biology), cell from the extrac ...
was obvious, and the microscopic pictures provided the first evidence that the cell membrane is a bilayer lipid structure. The following year, Bangham, his colleague Malcolm Standish, and Gerald Weissmann, an American physician, established the integrity of this closed, bilayer structure and its ability to release its contents following detergent treatment (structure-linked latency). During a Cambridge pub discussion with Bangham, Weissmann first named the structures "liposomes" after something which laboratory had been studying, the lysosome: a simple organelle whose structure-linked latency could be disrupted by detergents and streptolysins. Liposomes are readily distinguishable from micelles and hexagonal lipid phases through negative staining transmission electron microscopy. Bangham, with colleagues Jeff Watkins and Standish, wrote the 1965 paper that effectively launched what would become the liposome "industry." Around that same time, Weissmann joined Bangham at the Babraham. Later, Weissmann, then an emeritus professor at New York University School of Medicine, recalled the two of them sitting in a Cambridge pub, reflecting on the role of lipid sheets in separating the cell interior from its exterior milieu. This insight, they felt, would be to cell function what the discovery of the double helix had been to genetics. As Bangham had been calling his lipid structures "multilamellar smectic mesophases," or sometimes "Banghasomes," Weissmann proposed the more user-friendly term liposome.


Mechanism


Encapsulation in liposomes

A liposome has an aqueous solution core surrounded by a
hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...
membrane, in the form of a
lipid bilayer The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes form a continuous barrier around all cell (biology), cells. The cell membranes of almost all organisms and many viruses a ...
;
hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are n ...
solutes In chemistry, a solution is defined by IUPAC as "A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are ...
dissolved in the core cannot readily pass through the bilayer. Hydrophobic chemicals associate with the bilayer. This property can be utilized to load liposomes with hydrophobic and/or hydrophilic molecules, a process known as encapsulation. Typically, liposomes are prepared in a solution containing the compound to be trapped, which can either be an aqueous solution for encapsulating hydrophilic compounds like proteins, or solutions in organic solvents mixed with lipids for encapsulating hydrophobic molecules. Encapsulation techniques can be categorized into two types: passive, which relies on the stochastic trapping of molecules during liposome formation, and active, which relies on the presence of charged lipids or transmembrane ion gradients. A crucial parameter to consider is the "encapsulation efficiency," which is defined as the amount of compound present in the liposome solution divided by the total initial amount of compound used during the preparation. In more recent developments, the application of liposomes in single-molecule experiments has introduced the concept of "single entity encapsulation efficiency." This term refers to the probability of a specific liposome containing the required number of copies of the compound.


Delivery

To deliver the molecules to a site of action, the lipid bilayer can fuse with other bilayers such as the
cell membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...
, thus delivering the liposome contents; this is a complex and non-spontaneous event, however, that does not apply to nutrients and drug delivery. By preparing liposomes in a solution of
DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
or
drugs A drug is any chemical substance other than a nutrient or an essential dietary ingredient, which, when administered to a living organism, produces a biological effect. Consumption of drugs can be via inhalation, injection, smoking, ingestio ...
(which would normally be unable to
diffuse Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
through the membrane) they can be (indiscriminately) delivered past the lipid bilayer. Liposomes can also be designed to deliver drugs in other ways. Liposomes that contain low (or high) pH can be constructed such that dissolved aqueous drugs will be charged in solution (i.e., the pH is outside the drug's pI range). As the pH naturally neutralizes within the liposome (
protons A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' ( elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an electron (the pro ...
can pass through some membranes), the drug will also be neutralized, allowing it to freely pass through a membrane. These liposomes work to deliver drug by
diffusion Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
rather than by direct cell fusion. However, the efficacy of this pH regulated passage depends on the physiochemical nature of the drug in question (e.g. pKa and having a basic or acid nature), which is very low for many drugs. A similar approach can be exploited in the biodetoxification of drugs by injecting empty liposomes with a transmembrane pH gradient. In this case the vesicles act as sinks to scavenge the drug in the blood circulation and prevent its toxic effect. Another strategy for liposome drug delivery is to target
endocytosis Endocytosis is a cellular process in which Chemical substance, substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a Vesicle (biology and chem ...
events. Liposomes can be made in a particular size range that makes them viable targets for natural
macrophage Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...
phagocytosis Phagocytosis () is the process by which a cell (biology), cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs ph ...
. These liposomes may be digested while in the macrophage's
phagosome In cell biology, a phagosome is a vesicle formed around a particle engulfed by a phagocyte via phagocytosis. Professional phagocytes include macrophages, neutrophils, and dendritic cells (DCs). A phagosome is formed by the fusion of the cel ...
, thus releasing its drug. Liposomes can also be decorated with
opsonin Opsonins are extracellular proteins that, when bound to substances or cells, induce phagocytes to phagocytose the substances or cells with the opsonins bound. Thus, opsonins act as tags to label things in the body that should be phagocytosed (i.e. ...
s and
ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...
s to activate endocytosis in other cell types. Regarding pH-sensitive liposomes, there are three mechanisms of drug delivery intracellularly, which occurs via endocytosis. This is possible because of the acidic environment within endosomes. The first mechanism is through the destabilization of the liposome within the endosome, triggering pore formation on the endosomal membrane and allowing diffusion of the liposome and its contents into the cytoplasm. Another is the release of the encapsulated content within the endosome, eventually diffusing out into the cytoplasm through the endosomal membrane. Lastly, the membrane of the liposome and the endosome fuse together, releasing the encapsulated contents onto the cytoplasm and avoiding degradation at the lysosomal level due to minimal contact time. Certain anticancer drugs such as doxorubicin (Doxil) and daunorubicin may be administered encapsulated in liposomes. Liposomal
cisplatin Cisplatin is a chemical compound with chemical formula, formula ''cis''-. It is a coordination complex of platinum that is used as a chemotherapy medication used to treat a number of cancers. These include testicular cancer, ovarian cancer, c ...
has received
orphan drug An orphan drug is a medication, pharmaceutical agent that is developed to treat certain rare medical conditions. An orphan drug would not be profitable to produce without government assistance, due to the small population of patients affected by th ...
designation for pancreatic cancer from EMEA. A study provides a promising preclinical demonstration of the effectiveness and ease of preparation of valrubicin-loaded immunoliposomes (Val-ILs) as a novel nanoparticle technology. In the context of hematological cancers, Val-ILs have the potential to be used as a precise and effective therapy based on targeted vesicle-mediated cell death. The use of liposomes for transformation or
transfection Transfection is the process of deliberately introducing naked or purified nucleic acids into eukaryotic cells. It may also refer to other methods and cell types, although other terms are often preferred: " transformation" is typically used to des ...
of DNA into a host cell is known as lipofection. In addition to gene and drug delivery applications, liposomes can be used as carriers for the delivery of dyes to textiles, pesticides to plants, enzymes and nutritional supplements to foods, and cosmetics to the skin. Liposomes are also used as outer shells of some microbubble
contrast agent A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radiop ...
s used in contrast-enhanced ultrasound.


Dietary and nutritional supplements

Until recently, the clinical uses of liposomes were for targeted drug delivery, but new applications for the oral delivery of certain dietary and nutritional supplements are in development. This new application of liposomes is in part due to the low absorption and
bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. H ...
rates of traditional oral dietary and nutritional tablets and capsules. The low oral bioavailability and absorption of many nutrients is clinically well documented. Therefore, the natural encapsulation of lypophilic and
hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are n ...
nutrients within liposomes would be an effective method of bypassing the destructive elements of the gastric system and
small intestine The small intestine or small bowel is an organ (anatomy), organ in the human gastrointestinal tract, gastrointestinal tract where most of the #Absorption, absorption of nutrients from food takes place. It lies between the stomach and large intes ...
s allowing the encapsulated nutrient to be efficiently delivered to the cells and tissues. The term
nutraceutical Nutraceutical is a terminology evolved scientifically & also through marketing which is used to imply a pharmaceutical effect from plant extracts, compounds, food products which have efficacy and therapeutic influence on clinical outcomes and patien ...
combines the words
nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
and
pharmaceutical Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the ...
, originally coined by Stephen DeFelice, who defined nutraceuticals as "food or part of a food that provides medical or health benefits, including the prevention and/or treatment of a disease". However, currently, there is no conclusive definition of nutraceuticals yet, to distinguish them from other food‐derived categories, such as food (dietary) supplements, herbal products, pre‐ and probiotics, functional foods, and fortified foods. Generally, this term is used to describe any product derived from food sources which is expected to provide health benefits additionally to the nutritional value of daily food. A wide range of nutrients or other substances with nutritional or physiological effects (EU Directive 2002/46/EC) might be present in these products, including
vitamin Vitamins are Organic compound, organic molecules (or a set of closely related molecules called vitamer, vitamers) that are essential to an organism in small quantities for proper metabolism, metabolic function. Nutrient#Essential nutrients, ...
s,
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...
s,
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...
s, essential fatty acids,
fibre Fiber (spelled fibre in British English; from ) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorp ...
s and various plants and herbal extracts. Liposomal nutraceuticals contain bioactive compounds with health-promoting effects. The encapsulation of bioactive compounds in liposomes is attractive as liposomes have been shown to be able to overcome serious hurdles bioactives would otherwise encounter in the gastrointestinal (GI) tract upon oral intake. Certain factors have far-reaching effects on the percentage of liposome that are yielded in manufacturing, as well as the actual amount of realized liposome entrapment and the actual quality and long-term stability of the liposomes themselves. They are the following: (1) The actual manufacturing method and preparation of the liposomes themselves; (2) The constitution, quality, and type of raw
phospholipid Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...
used in the formulation and manufacturing of the liposomes; (3) The ability to create homogeneous liposome particle sizes that are stable and hold their encapsulated payload. These are the primary elements in developing effective liposome carriers for use in dietary and nutritional supplements.


Manufacturing

The choice of liposome preparation method depends, i.a., on the following parameters: # the physicochemical characteristics of the material to be entrapped and those of the liposomal ingredients; # the nature of the medium in which the lipid vesicles are dispersed # the effective concentration of the entrapped substance and its potential toxicity; # additional processes involved during application/delivery of the vesicles; # optimum size, polydispersity and shelf-life of the vesicles for the intended application; and, # batch-to-batch reproducibility and possibility of large-scale production of safe and efficient liposomal products Useful liposomes rarely form spontaneously. They typically form after supplying enough energy to a dispersion of (phospho)lipids in a polar solvent, such as water, to break down multilamellar aggregates into oligo- or unilamellar bilayer vesicles. Liposomes can hence be created by sonicating a dispersion of amphipatic lipids, such as
phospholipids Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typi ...
, in water. Low
shear rate In physics, mechanics and other areas of science, shear rate is the rate at which a progressive shear strain is applied to some material, causing shearing to the material. Shear rate is a measure of how the velocity changes with distance. Simple ...
s create multilamellar liposomes. The original aggregates, which have many layers like an onion, thereby form progressively smaller and finally
unilamellar liposome A unilamellar liposome is a spherical liposome, a vesicle, bounded by a single bilayer of an amphiphilic lipid or a mixture of such lipids, containing aqueous solution inside the chamber. Unilamellar liposomes are used to study biological system ...
s (which are often unstable, owing to their small size and the sonication-created defects). Sonication is generally considered a "gross" method of preparation as it can damage the structure of the drug to be encapsulated. Newer methods such as extrusion, micromixing and Mozafari method are employed to produce materials for human use. Using lipids other than
phosphatidylcholine Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup. They are a major component of biological membranes and can easily be obtained from a variety of readily available sources, such as egg yolk or soyb ...
can greatly facilitate liposome preparation.


Prospect

Further advances in liposome research have been able to allow liposomes to avoid detection by the body's immune system, specifically, the cells of
reticuloendothelial system In anatomy the term reticuloendothelial system (abbreviated RES), often associated nowadays with the mononuclear phagocyte system (MPS), was employed by the beginning of the 20th century to denote a system of specialised cells that effectively cl ...
(RES). These liposomes are known as " stealth liposomes". They were first proposed by G. Cevc and G. Blume and, independently and soon thereafter, the groups of L. Huang and Vladimir Torchilin and are constructed with PEG (
Polyethylene Glycol Polyethylene glycol (PEG; ) is a polyether compound derived from petroleum with many applications, from industrial manufacturing to medicine. PEG is also known as polyethylene oxide (PEO) or polyoxyethylene (POE), depending on its molecular wei ...
) studding the outside of the membrane. The PEG coating, which is inert in the body, allows for longer circulatory life for the drug delivery mechanism. Studies have also shown that PEGylated liposomes elicit anti-IgM antibodies, thus leading to an enhanced blood clearance of the liposomes upon re-injection, depending on lipid dose and time interval between injections. In addition to a PEG coating, some stealth liposomes also have some sort of biological species attached as a ligand to the liposome, to enable binding via a specific expression on the targeted drug delivery site. These targeting ligands could be
monoclonal antibodies A monoclonal antibody (mAb, more rarely called moAb) is an antibody produced from a Lineage (evolution), cell lineage made by cloning a unique white blood cell. All subsequent antibodies derived this way trace back to a unique parent cell. Mon ...
(making an immunoliposome),
vitamin Vitamins are Organic compound, organic molecules (or a set of closely related molecules called vitamer, vitamers) that are essential to an organism in small quantities for proper metabolism, metabolic function. Nutrient#Essential nutrients, ...
s, or specific
antigen In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...
s, but must be accessible. Targeted liposomes can target certain cell type in the body and deliver drugs that would otherwise be systemically delivered. Naturally toxic drugs can be much less systemically toxic if delivered only to diseased tissues. Polymersomes, morphologically related to liposomes, can also be used this way. Also morphologically related to liposomes are highly deformable vesicles, designed for non-invasive transdermal material delivery, known as transfersomes. Liposomes are used as models for artificial cells. Liposomes can be used on their own or in combination with traditional antibiotics as neutralizing agents of bacterial toxins. Many bacterial toxins evolved to target specific lipids of the host cells membrane and can be baited and neutralized by liposomes containing those specific lipid targets. A study published in May 2018 also explored the potential use of liposomes as "nano-carriers" of fertilizing nutrients to treat malnourished or sickly plants. Results showed that these synthetic particles "soak into plant leaves more easily than naked nutrients", further validating the utilization of nanotechnology to increase crop yields.
Machine learning Machine learning (ML) is a field of study in artificial intelligence concerned with the development and study of Computational statistics, statistical algorithms that can learn from data and generalise to unseen data, and thus perform Task ( ...
has started to contribute to liposome research. For example,
deep learning Deep learning is a subset of machine learning that focuses on utilizing multilayered neural networks to perform tasks such as classification, regression, and representation learning. The field takes inspiration from biological neuroscience a ...
was used to monitor a multistep
bioassay A bioassay is an analytical method to determine the potency or effect of a substance by its effect on animal testing, living animals or plants (''in vivo''), or on living cells or tissues (''in vitro''). A bioassay can be either quantal or quantit ...
containing sucrose-loaded and nucleotides-loaded liposomes interacting with a lipid membrane-perforating
peptide Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...
.
Artificial neural network In machine learning, a neural network (also artificial neural network or neural net, abbreviated ANN or NN) is a computational model inspired by the structure and functions of biological neural networks. A neural network consists of connected ...
s were also used to optimize formulation parameters of
leuprolide Leuprorelin, also known as leuprolide, is a manufactured version of a hormone used to treat prostate cancer, breast cancer, endometriosis, uterine fibroids, for early puberty, as part of transgender hormone therapy, or to perform chemical ca ...
acetate An acetate is a salt formed by the combination of acetic acid with a base (e.g. alkaline, earthy, metallic, nonmetallic, or radical base). "Acetate" also describes the conjugate base or ion (specifically, the negatively charged ion called ...
loaded liposomes and to predict the particle size and the polydispersity index of liposomes.


See also

* Azotosome * Lamella (cell biology) * Langmuir–Blodgett film *
Lipid bilayer The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes form a continuous barrier around all cell (biology), cells. The cell membranes of almost all organisms and many viruses a ...
* Targeted drug delivery


References


External links


Journal of Liposome Research
{{Dosage forms, state=expanded Membrane biology Drug delivery devices Dosage forms