Permeability of anti-fouling PEGylated surfaces probed by fluorescence correlation spectroscopy

Abstract

The present work reports on in situ observations of the interaction of organic dye probe molecules and dye-labeled protein with different poly(ethylene glycol) (PEG) architectures (linear, dendron, and bottle brush). Fluorescence correlation spectroscopy (FCS) and single molecule event analysis were used to examine the nature and extent of probe–PEG interactions. The data support a sieve-like model in which size-exclusion principles determine the extent of probe–PEG interactions. Small probes are trapped by more dense PEG architectures and large probes interact more with less dense PEG surfaces. These results, and the tunable pore structure of the PEG dendrons employed in this work, suggest the viability of electrochemically-active materials for tunable surfaces.

Fluorescence correlation spectroscopy study of protein transport and dynamic interactions with clustered‐charge peptide adsorbents

“…First, agarose is known to form relatively large pores that can range from 9 to 90 nm in size [Langford et al ., ; Yao et al ., ]. As we have recently shown, soft porous substrates can form sieve‐like structures that sterically hinder the diffusion of probes such as dyes and proteins via hydrostatic effects [Daniels et al ., ]. Other proposed steric interactions that have been identified by FCS include coupling to higher‐order polymer vibrational modes [Wang and Zhu ].…”

“…Single‐molecule imaging and the extensive successful practical use of agarose‐based adsorbents offer strong evidence that there are only negligible nonspecific chemical interactions between the protein and the agarose. Thus, on the basis of both our experimental analysis and our more detailed recent study of sieve‐like behavior of porous soft interfaces [Daniels et al ., ], we believe that the primary contributor to the modification of protein mobility at the water/agarose interface is steric interactions.…”

“…We have used fluorescence correlation spectroscopy (FCS) to probe the dynamics and interactions of various probe molecules with hard and soft surfaces [Daniels et al ., ; Daniels et al ., ; Reznik et al ., ; Reznik et al ., ]. In particular, we have shown that it is possible to position the approximately 2‐µm‐high confocal Gaussian beam to span the interface using a piezoelectric positioning stage, such that hindered diffusion due to interfacial effects can be distinguished from free diffusion.…”

A neutron reflection study of adsorbed deuterated myoglobin layers on hydrophobic surfaces

“…This is in order for the contact of the protein's hydrophobic residues with the like surface to be maximized, and may be revealed by the native shape of the molecule ''squashing'' upon adsorption to hydrophobic surfaces. A better understanding of the effects of adsorption on protein conformation may also have important implications in the field of immunology, where the use of antibody-antigen assays involving the adsorption of protein antigen onto a solid surface are seeing widespread use [21,22].…”

On the pH-Responsive, Charge-Selective, Polymer-Brush-Mediated Transport Probed by Traditional and Scanning Fluorescence Correlation Spectroscopy

“…It is evident that at the basic pH, when the brush is in its collapsed state, the brush did not garner interaction of the probes. We recently explored the construction of molecular sieves using polymer brushes, and reported that pore size can greatly influence the inclusion and exclusion of probes from the brush, 19 resulting in a molecular sieve. 35 The high pH data shown in Figure 6 is consistent with the earlier studies and suggests that the more dense collapsed brush excludes the probes.…”