Direct imaging of the surface distribution of immobilized cleavable polyethylene oxide‐polybutadiene‐polyethylene oxide triblock surfactants by atomic force microscopy

Abstract

Cleavable amphiphilic triblock surfactants with methoxypolyethylene oxide (PEO) side-chains attached to polybutadiene (PBD) center blocks by ester linkages were synthesized. The PEO-PBD-PEO triblocks were adsorbed on hydrophobic silicon wafers and covalently stabilized by g-irradiation. The PEO side-chains were then cleaved from the PBD backbones by acid hydrolysis. Decoration of the immobilized centerblocks with b-cyclodextrin allowed direct imaging by standard atomic force microscopy techniques. Widely varied surface coverage, layer morphology and distributions of the PBD centerblocks were observed on surfaces coated with different triblock concentrations and PEO:PBD ratios. Surfaces coated from 1 mg/mL solutions of triblocks (near the critical aggregation concentration (CAC), 0.28-0.53 mg/mL) were sparsely coated, and triblocks containing 75-85% PEO exhibited negligible surface coverage, possibly due to poor adsorption or facile desorption during rinsing. Dense surface packings, albeit some with evident defects sufficiently large to allow for protein adsorption, were produced from 10 mg/mL triblock solutions (an order of magnitude above the CAC). This proof-of-concept report describes a method that may be useful in optimizing surface coatings on model substrates, and thus lend insight into optimization of coating conditions for economical production of non-fouling triblock-based PEO coatings on clinically relevant biomedical materials.

Cleaning requirements for silica‐coated sensors used in optical waveguide lightmode spectroscopy

“…Line scans were used to determine an average peak‐to‐valley height, and average root mean squared (RMS) roughness was calculated from only the highest surfaces of the waveguide crests. Waveguide valleys and presumed contaminants (greater than 8 nm) were masked out for roughness calculations.…”

Building a working understanding of protein adsorption with model systems and serendipity

“…But poloxamer-like, triblock copolymers that incorporate vinyl group-rich hydrophobic center blocks, for example, are a potentially attractive option for synthesis of stable PEO coatings on the kinds of hydrophobic plastic materials used in practice. Vinyl groups in the polybutadiene (PB) backbone will form radicals upon exposure to UV-or -irradiation under water [81][82][83][84], directly and permanently linking the triblocks to the otherwise unmodified biomaterial surface. This kind of non-invasive approach would avoid the use of toxic and expensive crosslinkers or harsh solvents that may alter the properties of the underlying material.…”

Preparation and evaluation of PEO‐coated materials for a microchannel hemodialyzer

“…In this research we overcome this obstacle and avoid the need for pretreatment entirely, by using triblock copolymers that incorporate a vinyl group‐rich polybutadiene center block to produce stable PEO coatings on the materials used in this work. Vinyl groups in the polybutadiene (PB) backbone will form radicals upon exposure to UV‐ or γ ‐irradiation under water, directly and permanently linking the triblocks to the otherwise unmodified biomaterial surface. This noninvasive approach avoids the use of toxic and expensive crosslinkers or harsh solvents that may alter the properties of the underlying material, and is directly applicable to most medical materials (e.g., arterial/venous accesses, blood tubing, polymeric devices, etc.…”