Publication

RAFT homo- and copolymerization of N-acryloyl-morpholine, piperidine, and azocane and their self-assembled structures

Jeffrey Alan Hubbell, Davide Demurtas, Yun Suk Jo, Jay Gantz
2008
Journal Articles

Abstract

We present new polymeric amphiphiles derived from N-acryloyl derivatives of the cyclic secondary amines: morpholine, piperidine, and azocane polymerized by reversible addition -fragmentation transfer (RAFT) polymerization. Both homopolymerization and block copolymerization of N-acryloylmorpholine (AM), N-acryloylpiperidine (AP), and N-acryloylazocane (AH) were carried out. The block copolymeric amphiphiles, poly[(N-acryloylmorpholine)-block-(N-acryloylpiperidine)] (PAM-PAP) and poly[(N-acryloylmorpholine)-block-(N-acryloylazocane)] (PAM-PAH) were investigated, PAM being a hydrophile, and PAP and PAH being hydrophobes. Moreover, to compare PAM as a hydrophilic block with poly(ethylene glycol) (PEG), poly[(ethylene glycol)block-(N-acryloylpiperidine)] (PEG-PAP) was also formed. In all cases, the degree of polymerization was well-controlled and polymers were obtained in monomodal distributions. The macroamphiphile aggregates in water were reproducibly well-formed by dialysis with a size range between 10 and 70 nm as characterized by dynamic light scattering (DLS). The morphology of the aggregates was examined by transmission electron microscopy (TEM). All aggregates formed from PAM-PAP and PAM-PAH series, up to 0.76 and 0.85 hydrophobic weight fraction, respectively, revealed spherical micelles, whereas coexistence of spherical micelles and/or polymersomes was observed from PEG-PAP at a hydrophobic weight fraction of 0.91. From study of copolymer segregation behavior, PEG-PAP and PAM-PAH span the weak segregation region (WSR) as well as the strong segregation region (SSR), whereas PAM-PAP is positioned in the WSR, owing to the greater hydrophobicity of PAH than PAP. PAM yielded similar aggregation results to PEG when copolymerized with hydrophobic blocks. As a model drug, everolimus was loaded in PAM(0.15)-PAH(0.85) micelles. After loading the drug, the micelle hydrodynamic diameter was slightly increased from 43 +/- 0.1 to 52 +/- 1.8 nm. Everolimus was encapsulated with 60 +/- 7.8% of efficiency and was released over 3 wk in PBS (pH 7.4, 10 mM) at 37 degrees C.

Official source

Jeffrey Alan Hubbell, Davide Demurtas, Yun Suk Jo, Jay Gantz
2008
Journal Articles

Abstract

Official source

Related concepts (32)

Micelle

A micelle (maɪˈsɛl) or micella (maɪˈsɛlə) (plural micelles or micellae, respectively) is an aggregate (or supramolecular assembly) of surfactant amphipathic lipid molecules dispersed in a liquid, forming a colloidal suspension (also known as associated colloidal system). A typical micelle in water forms an aggregate with the hydrophilic "head" regions in contact with surrounding solvent, sequestering the hydrophobic single-tail regions in the micelle centre. This phase is caused by the packing behavior of single-tail lipids in a bilayer.

Hydrophobe

In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thus, prefer other neutral molecules and nonpolar solvents. Because water molecules are polar, hydrophobes do not dissolve well among them. Hydrophobic molecules in water often cluster together, forming micelles. Water on hydrophobic surfaces will exhibit a high contact angle.

Ultrahydrophobicity

In chemistry and materials science, ultrahydrophobic (or superhydrophobic) surfaces are highly hydrophobic, i.e., extremely difficult to wet. The contact angles of a water droplet on an ultrahydrophobic material exceed 150°. This is also referred to as the lotus effect, after the superhydrophobic leaves of the lotus plant. A droplet striking these kinds of surfaces can fully rebound like an elastic ball. Interactions of bouncing drops can be further reduced using special superhydrophobic surfaces that promote symmetry breaking, pancake bouncing or waterbowl bouncing.

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