Amphiphilic gradient copolymers of 2‐methyl‐ and 2‐phenyl‐2‐oxazoline: self‐organization in aqueous media and drug encapsulation

Abstract

Gradient (or pseudo‐diblock) copolymers were synthesized from 2‐methyl‐2‐oxazoline and 2‐phenyl‐2‐oxazoline monomer mixtures via cationic polymerization. The self‐assembling properties of these biocompatible gradient copolymers in aqueous solutions were investigated, in an effort to use the produced nanostructures as nanocarriers for hydrophobic pharmaceutical molecules. Dynamic and static light scattering as well as AFM measurements showed that the copolymers assemble in different supramolecular nanostructures (spherical micelles, vesicles and aggregates) depending on copolymer composition. Fluorescence spectroscopy studies revealed a microenvironment of unusually high polarity inside the nanostructures. This observation is related partly to the gradient structure of the copolymers. The polymeric nanostructures were stable with time. Their structural properties in different aqueous media—PBS buffer, RPMI solution—simulating conditions used in pharmacological/medicinal studies, have been also investigated and a composition dependent behavior was observed. Finally, the hydrophobic drug indomethacin was successfully encapsulated within the gradient copolymer nanostructures and the properties of the mixed aggregates were studied in respect to the initial copolymer assemblies. The produced aggregates encapsulating indomethacin showed a significant increase of their mass and size compared to original purely polymeric ones. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Solution Behavior of Hydrolyzed Gradient Methyl/Phenyl Oxazoline Copolymers and Complexation with DNA

“…Similar results have been obtained before for aggregates of amphiphilic oxazoline containing copolymers. [ 35,47,48 ] In Figure 3 aggregates show spherical morphology of an average radius 100 nm in general agreement with light scattering results. The slightly larger sizes of the copolymer aggregates in SEM images compared to the DLS technique were probably caused by the drying effects of HMPOx solutions on silicon wafers, which may impart a spreading of the structures on the surface.…”

“…Additionally, the aggregation numbers are higher than the ones in water solution because of the reduction of the electrostatic interactions. As in aqueous HMPOx solutions, the hydrodynamic values of HMPOx in PBS solutions are higher than those of the individual MPOx in PBS, [ 35 ] a result that suggests the formation of aggregates. In parallel, the R g / R h ratios (≈0.8) for both HMPOx in PBS, indicate spherical particles in solutions.…”

“…[ 19,[35][36][37][38][39] In the spectra of MPOx copolymers, peaks in the 679-820 cm −1 region are correlated to the aromatic C-H out-of-plane bending vibrations of the phenyl groups of the PhOx monomeric units, whereas peaks in the range 1011-1125 cm −1 are related to C-C and C-N groups. The asymmetric stretching vibrations of -N-CH 2 -group of the main chain and in-plane bending of CH 2 are observed at 1476 cm −1 , while the vibration of C=O group is evident at 1633 cm −1 .…”

The imaging and the fractal metrology ofchimericliposomal Drug Delivery nano Systems: the role of macromolecular architecture of polymeric guest

“…The PEO-b-PCL block copolymer was prepared by ring opening polymerization of "-caprolactone monomer using a monohydroxy terminated PEG (Sigma-Aldrich Chemical Co.) (M n ¼ 5000) as the macroinitiator and stannous octoate as the catalyst (Pippa et al, 2013a). The MPOx amphiphilic gradient block copolymers were prepared via cationic polymerization (Milonaki et al, 2012). In this copolymer, phenyl-oxazoline segments comprise the hydrophobic components and methyl-oxazoline segments the hydrophilic ones.…”

Gradient Sequence π-Conjugated Copolymers

“…To date, most gradient sequence copolymers have been synthesized from vinyl-containing monomers (37)(38)(39)(40). These reports have demonstrated that the gradient sequence materials exhibit unique properties compared to their block, random and alternating counterparts.…”