Biomimetic Monolayer and Bilayer Membranes Made From Amphiphilic Block Copolymer Micelles

Abstract

The deposition of amphiphilic poly(ethylene oxide)-block-poly(butadiene) (PEO-b-PBD) copolymer micelles is demonstrated on solid substrates. Depending upon surface chemistry, micelle adsorption creates either monolayer or bilayer films. Lateral diffusion measurements reveal that strong coupling between hydrophilic surfaces and PEO blocks creates immobile bilayers, while monolayers retain the fluidity previously observed in vesicular assemblies.

Diblock Copolymer Micelles and Supported Films with Noncovalently Incorporated Chromophores: A Modular Platform for Efficient Energy Transfer

“…By contrast, this effect was not observed in a lipid-based system containing BODIPY-HPC and BC-1 for which solution-based lipid vesicles had comparable ETE to supported lipid bilayers (see Table S4 PBD monolayers have lateral mobility comparable to the same dye in lipid membranes. 27 These mobility patterns for BODIPY-HPC in bilayer and monolayer samples were also observed in the current study, but with an additional interesting optical response due to the presence or absence of the BC-1 acceptor. For polymer bilayers, bleaching of BODIPY led to no FRAP recovery ( Figure 4A), as expected, however, preferential bleaching of BC-1 caused an increased BODIPY fluorescence intensity in the 'bleach region' (Figure 4C).…”

“…27 Static We found that PEO-b-PBD/chromophore nanocomposites could be assembled with any donor or acceptor concentration up to ~3% (chromophore mol% relative to polymer concentration) before chromophore aggregation effects were observed. Therefore, for detailed characterization, we generated sets of samples at chromophore concentrations that exhibited good energy transfer (10-60% efficiency) and no observed aggregation.…”

“…[23][24][25] Hydrophobic fluorescent dyes and quantum dots have previously been incorporated into longchain vesicle-forming PEO-b-PBD, showing the potential for 'hydrophobic loading'. 26 Recently, a 1.3/1.2 kDa (block/block ratio) PEO-b-PBD copolymer was extensively characterized 27 as forming micelles in aqueous solution but reorganizing into bilayer films of similar scale to lipid bilayers when deposited onto hydrophilic surfaces and monolayer films on hydrophobic surfaces.…”

“…In all cases, the hydrophobic PBD block was sequestered and the hydrophilic PEO block exposed to the aqueous solvent, analogous to lipid arrangements, leading to its description as a biomimetic polymer 27 and making it an interesting candidate for further application. In the A BODIPY chromophore was chosen as the excitation 'donor' for its favorable stability, hydrophobic character, low tendency to self-aggregate, high extinction coefficient, high fluorescence quantum yield and relatively sharp emission band.…”

“…Second, ultimately, there is interest in coupling light-harvesting systems to energy-transducing surfaces, so investigation of thin-film geometries provides a step in that direction. We took advantage of the ability of PEO-b-PBD to form well-defined bilayer films on hydrophilic surfaces and monolayers on hydrophobic surfaces 27 . PEO-b-PBD/chromophore micelle samples with a range of BC-1 concentrations (0-2.0%) and similar BODIPY-HPC concentration (~0.5%) were deposited onto hydrophilic glass substrates to form surface-supported bilayer films and characterized (under liquid) using laserscanning confocal microscopy (LSCM) and atomic force microscopy (AFM).…”