A few amphiphilic polymers are commercially available for R & D purposes, e.g., several linear PEG-PLGA block-copolymers. However, polymers for human use that require manufacturing according to GMP are less commonly available. Also, customer-specific amphiphilic polymers are dedicatedly synthesized in most cases. celares GmbH is a specialist for the synthesis and for the GMP-compliant manufacturing of amphiphilic polymers for drug delivery as well as for non-medicinal applications.
Use of functionalized polymers
Functionalized amphiphilic polymers presently play an integral role in the advancement of drug delivery technology by providing controlled release of therapeutic agents. The release may happen in different ways: constant dosing over long periods, cyclic dosage or tunable release of the drug. Often, such polymers readily form nanoparticles covering hydrophilic but also hydrophobic drugs. Moreover, these polymers are frequently used as carriers to stabilize and deliver sensitive drugs (e.g., oligonucleotides) or water-insoluble drugs to their targets.
Besides medicinal applications, functionalized amphiphilic polymers, e.g., hyperbranched bowl-shape polymers, may serve as blocking agents to reduce non-specific binding in diagnostic assays. Other, appropriately functionalized polymers act as non-covalent binders for certain solids, liquids or gases.
Nanoparticles formed from polymers (red parts = API)
Principles and structures of polymers for drug delivery
Most drugs require an appropriate formulation for their successful application as pharmaceuticals. The reasons for formulating may be: aqueous insolubility of the drug, its sensitivity/instability, its fast clearance or its unspecific distribution in human body, etc. Polymers, particularly amphiphilic polymers are often used as key excipient to properly formulate the drug. Such polymers are, for example, poly lactic acids (PLA) or poly glycolic acids (PGA) or combinations thereof, also PEG block-copolymers with PLA/PGA and PEG block-copolymers with poly amino acid derivatives. Other suitable polymers are linear or branched polyamines, such as branched polyethylene amines (bPEIs), among others. Recently, dendrimer-like bowl-shaped polymers such as hyperbranched polyglycerols (HPGs) have been added to the group of functional amphiphilic polymers for drug delivery.
Amphiphilic polymers for other purpose
Functionalized amphiphilic polymers may also be suitable for other non-medicinal application. Blocking of surfaces, such as the plastic surfaces of the commonly used well plates, is necessary to reduce or prevent unspecific binding and to increase the signal to noise ratio in diagnostic assays. Bovine serum albumin (BSA) is a well established blocking agent serving this purpose. A major drawback of BSA is its animal origin, resulting in a substantial batch-to-batch variability, which is unacceptable for several applications. Moreover, certain countries no longer allow the use of animal material in medicinal products or diagnostics. Bowl-shape HPGs with customized 3D structure can substitute BSA as blocking agents. Bowl-shape HPGs are purely synthetic and thus overcome the major obstacles described above.