Liposomes are spherical artificial vesicles consisting of one or more lipid bilayers. Liposomes are utilized to increase stability, solubility, bioaccessibility, and bioavailability of bioactive compounds, and to provide targeted delivery and controlled release in food, pharmaceutical, and cosmetic industries, due to their structural versatility, biocompatibility, biodegradability, non-toxic, and non-immunogenicity nature.
The main component of liposomes are glycerophospholipids, which are amphiphilic lipids composed of a glycerol molecule bound to a phosphate group and to two fatty acid chains that may be saturated or unsaturated. The phosphate group can be also bonded to another organic molecule. According to this organic group, natural phospholipids are classified as phosphatidic acid (PA), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylglycerol (PG), and phosphatidylserine (PS). Glycerophospholipids that are responsible to form liposomes can be divided in two different forms: natural and synthetic. The most natural phospholipids used to produce liposomes are PC and PE, that are abundant phosphatides in plants and animals.
Synthetic phospholipids are produced from natural lipids. Modification in head groups, aliphatic chains and alcohols of natural phospholipids creates a variety of synthetic phospholipids, that have proved to be more stable, such as 1,2-Distearoyl-sn-glycero-3-phosphocholine (DSPC), 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and 1,2-Distearoyl-sn-glycero3-phosphoethanolamine (DSPE). DPPC can be used to prepare temperature-sensitive liposomes as the primary lipid. Because DPPC membranes undergo the phase transition at 41℃, DPPC based liposomes release encapsulated molecules at this clinically attainable temperature.
Figure 1. Different types of liposomes in drug delivery systems. (Frontiers in Pharmacology, 2015)
In addition, the stability difficulties of liposomes can be solved by surface modification of the liposomes with amphipathic polyethylene glycol (PEG), coating liposomes with chitin derivatives, freeze drying, polymerization, etc.
We have developed Liposome Technology with plenty of advantages:
-Nontoxic, biocompatible, and completely biodegradable
-Enhanced bioactivity and efficacy
-Site avoidance effect
-Increased stability via encapsulation processes
-Reduced toxicity of encapsulated drugs
-Flexibility for active targeting
Novel liposome designs become more and more important because it manipulates the solubility of encapsulated small organic molecules, protects the embedded agents from degradation, and achieves site-specific delivery. We provide novel liposome formulations with different properties to both academic and industrial clients. The general 4-step process to prepare liposomes involves drying down the lipids, dispersing the lipids, purification of liposomes and analysis of the final products. We go beyond convention liposome preparation and offers analytical method developments as well.
Figure 2. Schematic representation of the liposome preparation procedure
Formulation design & screening
•All types of liposomes and other lipid-based drug delivery systems
•Specialized in formulation of difficult compounds
•Formulation of small molecules, peptides/proteins, nucleic acids
•Solubility enhancement using liposomes and lipid-based systems
•Controlled/slow drug release systems
• Pre-formulation, formulation feasibility and prototype development
• Extrusion, homogenization, microfluidization, sonication and others
•Process development, scale-up and process optimization (Design-of-Experiments) and sterile grade filterability studies