A constant problem in drug therapies with non-water-soluble ingredients is their low bioavailability - this means, for example, that only a small percentage of the drug dose actually circulates in the body for a longer period of time. A common approach to solving this problem is the encapsulation of these ingredients in biodegradable hydrophobic polymers, e.g. in poly(ester amide)e (PEA), which acts as a transport medium for the active ingredient. In addition, the blood circulation times can be optimized by so-called "stealth" polymers, which act like a "magic hood" and "hide" the cargo from the immune system.
The previous gold standard for these "magic hoods" was the polymer poly(ethylene glycol), but this has severe disadvantages. The synthesis and in-depth characterisation of alternatives to this was investigated within the framework of the Collaborative Research Centre PolyTarget (SFB 1278) for potential applications in drug delivery. The outcome is a system of amphiphilic block copolymer composed of poly(2-ethyl-2-oxazoline) (PEtOx) as well as natural amino acids and glycolic acid.
The exposure of a PEtOx shell demonstrates a necessity in order to benefit from the “stealth” behaviour of the cargo. Thus, phase separation in aqueous dispersion must be ensured. Molecular dynamic simulations and thermal analysis of the resulting materials indicated bulk miscibility, whereas cryo-transmission electron microscopy of aqueous dispersions revealed the presence of vesicular structures, that can only be present if phase segregation occurred. With these results, the materials could potentially be used in drug delivery vehicles.
In future studies, the CRC researchers now plan to focus on biodegradability and the encapsulation of hydrophobic drugs.
You'll find the complete article titled "Block Copolymers Composed of PEtOx and Polyesteramides Based on Glycolic Acid, l-Valine, and l-Isoleucine" here.