Synthesis and pH-dependent micellization of diblock copolymer mixtures

Abstract

This work focused on the preparation and the aqueous solution properties of hybrid polymeric micelles consisting of a hydrophobic poly(epsilon-caprolactone) (PCL) core and a mixed shell of hydrophilic poly(ethylene oxide) (PEO) and pH-sensitive poly(2-vinylpyridine) (P2VP). The hybrid micelles were successfully prepared by the rapid addition of acidic water to a binary solution of PCL(34)-b-PEO(114) and PCL(32)-b-P2VP(52) diblock copolymers in N,N-dimethylformamide. These micelles were pH-responsive as result of the pH-dependent ionization of the P2VP block. The impact of pH on the self-assembly of the binary mixture of diblocks-thus on the composition, shape, size and surface properties of the micelles-was studied by a variety of experimental techniques, i.e., dynamic and static light scattering, transmission electron microscopy, Zeta potential, fluorescence spectroscopy and complement hemolytic 50 test.

Expanding mesoporosity of triblock-copolymer-templated silica under weak synthesis acidity

“…With the gradual elevation of the pH value above the isoelectric point of silica, the quantity of negative charges on the silica species would increase accordingly because the chemical equilibrium tend to drive the deprotonation of the surface silanol groups to form Si-O À [26], which has positive effect on enhancing the electrostatic interaction. In contrast, the quantity of positive charges on the template micelles would concurrently decrease due to the diminishment in the protonation degree of the PEO chains [46], which has negative effect on enhancing the electrostatic interaction. As a result, the electrostatic interactions between the silica species and the template might undergo non-monotonic evolutions with the pH variations.…”

“…Under strong acidities, the corona region of the copolymer micelle would be deeply solvated because the intensive protonation of the PEO chains could reinforce the hydrophilicity of the EO units. But elevation of the pH values would induce favorable non-polar conformations in PEO blocks due to the deprotonation [46], enhancing attractive forces between neighboring PEO chains, concurrently resulting in the depletion of the solvent water from the inner part of the PEO shell. Therefore, the inner EO units adjacent to the PPO segments become part of the hydrophobic core under moderate acidities, leading to enlarged mesopore sizes and pore volumes in the silica products (Table 1).…”

Effect of Zeta Potential on the Properties of Nano-Drug Delivery Systems - A Review (Part 1)

“…Electrokinetic phenomena and electroacoustic phenomena are the usual sources of data for calculation of ZP. The ZP of a dispersion is measured by applying an electric field across the dispersion [17]. Particles within the dispersion with a ZP will migrate toward the electrode of opposite charge with a velocity proportional to the magnitude of the zeta potential.…”

“…Sample dilution using equilibrium supernatant is the best justified way to perform this dilution. Equilibrium supernatant is readily obtained by centrifugation [17][18].…”

Effects of pH‐Sensitive Groups on Poly(ethylene oxide)‐block‐poly(ϵ‐caprolactone) Block Copolymer Micelles Used as Drug Carriers

“…vinylpyridine 196 mg L − 1 , 175 mg L − 1 8900, 9200 [ 45 ] Our group has focused on the study of mPEG -b-PCL-b -PAA/PMAA [poly(ethylene oxide)-block-poly( ε -caprolactone)-block-poly(acrylic acid) or poly(methacrylic acid)], which is made pH sensitive by attaching t-BA ( tertbutylacrylate) or t-BMA ( tert -butyl methacrylate) to the PCL terminal. In this project, we investigated the effect of molecular weight and chemical structure on the selfassembling properties of the amphiphilic polymer in a systematic manner, with particular attention to drugloading and release behaviors.…”