Two-dimensional self-assembly of amphiphilic block copolymers at the air/water interface and nanoparticles for drug detoxification applications .

摘要

The two-dimensional self-assembly at the air/water (A/W) interface of various block copolymers (dendrimer-like polystyrene-b-poly( tert-butylacrylate) (PS-b-PtBA) and polystyrene-b-poly(acrylic acid) (PS-b-PAA), linear and five-arm star poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL), and three-arm star triethoxysilane-functionalized polybutadiene-b-poly(ethylene oxide) (PB(Si(OEt)3)- b-PEO)) was investigated through surface pressure measurements (isotherms, isobars, isochores, and compression-expansion hysteresis experiments) and atomic force microscopy (AFM) imaging. The PS-b-P tBA and the PS-b-PAA samples formed well-defined circular surface micelles at low surface pressures with low aggregation numbers (∼ 3-5) compared to linear analogues before collapse of the P tBA chains and aqueous dissolution of the PAA segments take place around 24 and 5 mN/m, respectively. The linear PEO-b-PCL samples exhibited three phase transitions at 6.5, 10.5, and 13.5 mN/m corresponding respectively to PEO aqueous dissolution, PEO brush formation, and PCL crystallization. The two PEO phase transitions were not observed for the star-shaped PEO- b-PCL samples because of the negligible surface activity of the star-shaped PEO core compared to its linear analogue. The PB(Si(OEt)3)- b-PEO sample was cross-linked at the A/W interface by self-condensation of the pendant triethoxysilane groups under acidic conditions, which resulted in the formation of a two-dimensional PB network containing PEO pores with controllable sizes.; With a view toward drug detoxification therapy, the encapsulation abilities of oil core-silica shell nanocapsules and molecularly imprinted nanoparticles were also investigated by electrochemical (cyclic voltammetry) and optical (fluorescence and UV-vis spectroscopies) techniques. The core-shell nanocapsules were shown to efficiently remove large amounts of organic molecules present in aqueous solutions, with the silica shell acting analogously to a chromatographing layer. The molecularly imprinted nanoparticles were prepared by the non-covalent approach and by miniemulsion polymerization. Binding studies on the molecularly imprinted nanoparticles in aqueous solutions under physiological pH conditions indicated that, in the absence of specific imprinting, the uptake of toxic drugs was mainly driven by non-specific hydrophobic interactions. As demonstrated with the use of the antidepressant amitriptyline, in the presence of specific imprinting the uptake significantly increased as the amount of specific binding sites was increased.