Synthesis and Evaluation of a Star Amphiphilic Block Copolymer from Poly(ε-caprolactone) and Poly(ethylene glycol) as a Potential Drug Delivery Carrier

Abstract

A star polymer composed of amphiphilic block copolymer arms has been synthesized and characterized. The core of the star polymer is polyamidoamine (PAMAM) dendrimer, the inner block in the arm is lipophilic poly(epsilon-caprolactone) (PCL), and the outer block in the arm is hydrophilic poly(ethylene glycol) (PEG). The star-PCL polymer was synthesized first by ring-opening polymerization of epsilon-caprolactone with a PAMAM-OH dendrimer as initiator. The PEG polymer was then attached to the PCL terminus by an ester-forming reaction. Characterization with SEC, (1)H NMR, FTIR, TGA, and DSC confirmed the star structure of the polymers. The micelle formation of the star copolymer (star-PCL-PEG) was studied by fluorescence spectroscopy. Hydrophobic dyes and drugs can be encapsulated in the micelles. A loading capacity of up to 22% (w/w) was achieved with etoposide, a hydrophobic anticancer drug. A cytotoxicity assay demonstrated that the star-PCL-PEG copolymer is nontoxic in cell culture. This type of block copolymer can be used as a drug delivery carrier.

Synthesis and Characterization of Biodegradable Amphiphilic Star and Y-Shaped Block Copolymers as Potential Carriers for Vinorelbine

“…After one more night of stirring the mixture was dialyzed against double distilled water using Spectra/Por 1 Molecular porous Dialysis Membrane. The water was exchanged at first, second, third, sixth and twelfth hours [9,17,31,32]. Obtained micelles were filtered using Fisher brand Syringe Filters with a nylon membrane with pore size: 0.2 µm.…”

“…The unimers with arm numbers of 16 or 32 have shown the high stability, drug delivery efficacy and physicochemical properties compared to unimers with a smaller arm number. Star-shaped polymers with a smaller arm number have been found to either form a relatively loose outer PEG shell, or to have a weak capacity of carrying drug molecules [7,17]. Although poly(ε-caprolactone) (PCL) and PEG are very well known biodegradable and biocompatible polymeric materials, they are not allowed to be used above a certain concentration because of toxicity considerations [18].…”

Novel Nanomaterials for Clinical Neuroscience

“…For example, hydrophobic and hydrophilic polymer blocks can be grafted to the surface resulting in formation of unimolecular micelles ( Fig. 3b; Liu et al 2000;Wang et al 2005;Tsai et al 2006;Yang and Kao 2006). Unlike conventional micelles, such unimolecular micelles are stable upon dilution and do not disintegrate during circulation in the body.…”

Nanomedicine in the diagnosis and therapy of neurodegenerative disorders

“…The promising results of these trials suggest that polymeric micelles are likely to find practical use in medicine. Moreover, further advances in polymer chemistry resulted in the development of novel nanomaterials with unique spatial orientation of molecular groups, including dendrimers [150], star-polymers [151], and cross-linked polymer micelles [152][153][154][155]. In parallel, advances in nanomanufacturing and nanofabrication led to the development of carbon nanotubes [156,157], and polymeric nanofibers [158,159].…”

“…Examples include amphiphilic scorpion-like block copolymers with low critical micelle concentration (CMC) [151] as well as various types of unimolecular micelles based on amphiphilic star-like macromolecules with covalently bound hydrophobic cores [151,154,232,233]. Core-polymerization was employed to stabilize micelles of heterotelechelic amphiphilic block copolymers containing polymerizable groups at the ends of hydrophobic blocks [234].…”