Fabrication of thermosensitive PCL‐PNIPAAm‐PCL triblock copolymeric micelles for drug delivery

Abstract

A series of thermosensitive ABA type triblock poly(e-caprolactone)-bpoly(N-isopropylacrylamide)-b-poly(e-caprolactone) (PCL-PNIPAAm-PCL) copolymers with different molecular weights were synthesized by the combination of ring opening polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization. The critical micelle concentrations (CMCs) of the resulted four triblock copolymers in aqueous solution were determined to be 33. 8, 39.8, 35.5, and 41.7 mg/L, respectively, by fluorescence spectroscopy using pyrene as a fluorescence probe. Optical absorption measurements showed that the lower critical solution temperatures (LCSTs) of the copolymers were 35.8, 36.2, 35.2, and 36.2 8C, respectively, in distilled water, and 33.9, 34.2, 33.3, 34.6 8C, respectively, in PBS (pH ¼ 6.8, I ¼ 0.1). Transmission electron microscopy (TEM) showed that the self-assembled micelles exhibited a well-defined spherical shape with diameter of around 100 nm. The drug-loaded PCL-PNIPAAm-PCL micelles displayed thermosensitive controlled release behaviors. V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: [3048][3049][3050][3051][3052][3053][3054][3055][3056][3057] 2008

Folate‐mediated cell uptake of shell‐crosslinked spheres and cylinders

“…Toward this end, polymeric nanoparticles have been designed and synthesized to augment the drug's local concentration. [1][2][3][4][5] For example, Hubbell and coworkers have developed a drug delivery system with dual targeting moieties, which led up to a 72-fold increase in targeting to the extracellular compartment of articular cartilage in mice. 6 Although significant progress has been made in terms of identifying the targets and construction of targeting nanoparticles, the shape effect of the nanoparticle platform per se on cell binding and internalization through receptor-ligand interactions has not yet been investigated thoroughly.…”

Influence of the polymer structure over self‐assembly and thermo‐responsive properties: The case of PEG‐b‐PCL grafted copolymers via a combination of RAFT and ROP

“…The temperature was increased with an average speed of 0.75 8C/min and the value leading to the half of the transmittance drop was considered as LCST. 32,42,43 DLS measurements were performed with a Malvern Zetasizer Nano ZS at a scattering angle of 1738 (backscatter) to study the evolution of hydrodynamic diameters of the produced NPs as a function of the temperature. The sample was filtered with a 0.45-lm syringe filter before the measurement to remove dust.…”

“…[29][30][31] This kind of macromonomers has been already adopted in biomedical applications and literature experiments demonstrated its biocompatibility both in vitro and in vivo. 7,[32][33][34][35] Here, an oligo(e-caprolactone) macromonomer with three units of e-caprolactone functionalized with HEMA double bond is exploited (CL 3 MA). Moreover, in order to decrease the hydrophilicity of such compound, we also synthesized a propionyl version (PrCL 3 MA) in which the H-bonding from the OH-moiety is suppressed.…”

Advances in drug delivery systems based on synthetic poly(hydroxybutyrate) (co)polymers

“…[177,197], thus making these former methacrylate triblock copolymers valuable as double stimuli-responsive DDSs.…”