Nisin adsorption to hydrophobic surfaces coated with the PEO–PPO–PEO triblock surfactant Pluronic® F108

Abstract

The adsorption and elution of the antimicrobial peptide nisin at hydrophobic, silanized silica surfaces coated with the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) surfactant Pluronic F108 were measured in situ, with ellipsometry. While such layers are known to inhibit protein adsorption, nisin was observed to adsorb in multilayer quantities, to an extent similar to its adsorption at uncoated, hydrophobic surfaces. The rates of nisin adsorption and elution were generally slower at F108-coated surfaces. And, the sequential adsorption of nisin, including two adsorption-elution cycles at each surface, showed greater differences in adsorption rates between the first and second adsorption cycles, when evaluated at identical mass density, for uncoated relative to F108-coated surfaces. These results indicate that nisin adsorption occurs via "entrapment" within the PEO brush layer at F108-coated surfaces, in this way slowing adsorption and spontaneous elution, and inhibiting post-adsorptive molecular rearrangements by reducing the lateral mobility of nisin. While F108-coated layers rejected adsorption of serum albumin, sequential adsorption experiments carried out with nisin and albumin showed a low level of albumin adsorption when nisin was present at the interface.

Nisin antimicrobial activity and structural characteristics at hydrophobic surfaces coated with the PEO–PPO–PEO triblock surfactant Pluronic® F108

“…This may sug- gest some degree of stabilization against activity loss gained by nisin associated with the microspheres. This association is characterized by a high interfacial concentration of nisin consistent with its existence in multiple layers [1], and its "storage" in this form may have inhibited activity loss under solution conditions otherwise known to be unfavorable for nisin activity. Fig.…”

“…Nisin kills susceptible bacteria through a multi-step process that destabilizes the phospholipid bilayer of the cell and creates transient pores. Previous work on nisin structure and function, its mechanism of antimicrobial action, surface activity and potential for use as an antiinfective agent in medical device coatings, was summarized earlier [1]. In this paper we describe the antimicrobial activity of nisin-loaded, F108-coated polystyrene microspheres and F108-coated polyurethane catheter segments after incubation in the presence and absence of blood proteins.…”

“…In a previous paper we described the adsorption and elution behavior of nisin at silanized silica surfaces coated with the PEO-PPO-PEO triblock copolymer Pluronic ® F108 [1]. Comparison of nisin adsorption and elution kinetics at uncoated and F108-coated surfaces suggested nisin "entrapment" within the PEO brush layer, as opposed to adsorption to the PEO chains in a non-penetrating manner.…”

Effect of PEO coating on bubble behavior within a polycarbonate microchannel array: A model for hemodialysis

“…Theoretical and experimental evidence suggests that below the outer region of a PEO brush layer there exists a hydrophobic, inner region that is favorable for protein adsorption. 32,33 Thus, the PEO brush layer can also be "loaded" with (sufficiently small) therapeutic peptides (34) as well as functionalized by chain endactivation and bioconjugation. 35 The dynamics occurring at the hydrophobic inner layer play a lesser role in this study.…”

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

“…We have since described nisin adsorption and various aspects of its behavior at PEO-coated surfaces through ellipsometry [61], CD and assays of antibacterial activity [62], zeta potential [63], TOF-SIMS [64], anti-fibrinogen ELISA and other labeled fibrinogen assays [63,65], and optical waveguide lightmode spectroscopy (OWLS) [65,66]. The major outcome of those results is that nisin becomes entrapped within the hydrophobic, inner region of PEO brush layers (possessing sufficiently long PEO chains), and retains its antibacterial activity in that mode owing to its enhanced resistance to elution by dissolved protein (Fig.…”