Nanomaterials play an important role in our daily life and have become essential in the areas of medicine and pharmaceutical applications, often in connection to biomaterials. Advanced synthetic approaches offer the creation of such materials while tailoring their macromolecular size. Our research focuses on the fundamental characterization of such macromolecules in connection to their purpose in the life sciences by a quantitative description of their behavior in solution associated to absolute values of the molar mass, molecular solvation, and overall (hydrodynamic) size.
The synthetic gold standard in medical implementations are poly(ethylene glycol)s (PEG), because of their stealth effect toward the immune system, associated with low toxicity and noticed biocompatibility. An intense use of PEG in common commodity applications such as salves, creams, and in drug conjugation resulted in recent reports of antibodies. Therefore, alternatives, e.g. poly(2-oxazoline)s (POx) are more strongly coming into the focus of research.
Here, we present the solution characterization of PEG and its alternative POx, for use in biomaterial-related settings. We utilize two macromolecular characterization techniques in solution for such purpose, i.e. hydrodynamic analysis via viscometry and sedimentation-diffusion analysis as well as fractionation / separation techniques coupled to multi-angle laser light scattering (MALLS). The use of a hydrodynamic invariant concept comprises sedimentation, diffusion / molar masses, and intrinsic viscosity of the same macromolecule populations. This concept was used to achieve a quantitative interrelation of the results of experimentally different methods for macromolecule characterization.
We found that both PEG and POx assume a random coil conformation in solution. Interestingly, both macromolecules show the same hydrodynamic interrelation of parameters, though absolute values of individual hydrodynamic parameters differ considerably. In conclusion, our data open the gate for the replacement of PEG by POx with the desirable absolute physicochemical properties adjusted quantitatively on a well-informed basis.