Depletion versus Deflection: How Membrane Bending Can Influence Adhesion

Nam, Jin; Santore, Maria M.

doi:10.1103/physrevlett.107.078101

Cited by 11 publications

(9 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…That is, bacterial spreading will depend on the bacterial surface charge and its attraction, through a wedge-shaped water gap, to charges on the collector. Also important, bending resistance from a bacterium must be overcome by these adhesive interactions and can, as we have shown for vesicles, arrest spreading processes and lead to delayed responses. , The distribution of cationic nanoconstructs over the surface is therefore a critical design consideration in controlled bacterial, via the prevention of spreading. Ionic strength plays an additional role in spreading by determining the collector area, outside the instantaneous contact region, that is able to attract the bacterium.…”

Section: Discussionmentioning

confidence: 99%

Easy Come Easy Go: Surfaces Containing Immobilized Nanoparticles or Isolated Polycation Chains Facilitate Removal of Captured Staphylococcus aureus by Retarding Bacterial Bond Maturation

et al. 2014

Self Cite

View full text Add to dashboard Cite

Adhesion of bacteria is a key step in the functioning of antimicrobial surfaces or certain types of on-line sensors. The subsequent removal of these bacteria, within a ∼ 10-30 min time frame, is equally important but complicated by the tendency of bacterial adhesion to strengthen within minutes of initial capture. This study uses Staphylococcus aureus as a model bacterium to demonstrate the general strategy of clustering adhesive surface functionality (at length scales smaller than the bacteria themselves) on otherwise nonadhesive surfaces to capture and retain bacteria (easy come) while limiting the progressive strengthening of adhesion. The loose attachment facilitates bacteria removal by moderate shearing flow (easy go). This strategy is demonstrated using surfaces containing sparsely and randomly arranged immobilized amine-functionalized nanoparticles or poly-l-lysine chains, about 10 nm in size. The rest of the surface is backfilled with a nonadhesive polyethylene glycol (PEG) brush that, by itself, repels S. aureus. The nanoparticles or polymer chains cluster cationic functionality, providing small regions that attract negatively charged S. aureus cells. Compared with surfaces of nearly uniform cationic character where S. aureus adhesion quickly becomes strong (on a time scale less than 5 min), placement of cationic charge in small clusters retards or prevents processes that increase bacteria adhesion on a time scale of ∼ 30 min, providing "easy go" surfaces.

show abstract

Section: Discussionmentioning

confidence: 99%

Easy Come Easy Go: Surfaces Containing Immobilized Nanoparticles or Isolated Polycation Chains Facilitate Removal of Captured Staphylococcus aureus by Retarding Bacterial Bond Maturation

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…6,50 Estimating the excluded fibrinogen volume as 4.5 × 4.5 × 45 = 900 nm 3 , and using second and third virial coefficients of 0.0057 cm 3 mol/g 2 and 0.059 cm 6 mol /g 3 , respectively, to estimate the osmotic pressure, 38 (also used to calculate the brush height), the results are summarized in Table III.…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…These values were found to adequately predict measured depletion forces in a separate work. 38 Notable in Table II is that Brushes 1 and 2 are similar in PEG content while Brushes 2 and 3 are similar in height, allowing the importance of these parameters to be tested.…”

Section: Experimental Materials and Methodsmentioning

confidence: 99%

How Bacteria Adhere to Brushy PEG Surfaces: Clinging to Flaws and Compressing the Brush

et al. 2012

Self Cite

View full text Add to dashboard Cite

This study examined the compression of solvated polymer brushes on bioengineered surfaces during the initial stages of Staphylococcus Aureus (S. aureus) adhesion from gentle flow. A series of PEG [poly(ethylene glycol)] brushes, 7 to 17 nm in height and completely non-adhesive to proteins and bacteria, were modified by the incorporation of sparse isolated ~10 nm cationic polymer “patches” at their bases. These nanoscale regions, which lacked PEG tethers, were electrostatically attractive towards negative bacteria or proteins. S. aureus drawn to the interface by multiple adhesive patches compressed the PEG brush in the remaining contact region. The observed onset of bacterial or fibrinogen capture with increases in patch content was compared with calculations. Balancing the attraction energy (proportional to the number of patches engaging a bacterium during capture) against steric forces (calculated using the Alexander-DeGennes treatment) provided perspective on the brush compression. The results were consistent with a bacteria-surface gap on the order of the Debye length in these studies. In this limit of strong brush compression, structural features (height, persistence length) of the brush were unimportant so that osmotic pressure dominated the steric repulsion. Thus, the dominant factor for bacterial repulsion was the mass of PEG in the brush. This result explains empirical reports in the literature that identify the total PEG content of a brush as a criteria for prevention of bioadhesion, independent of tether length and spacing, within a reasonable range for those parameters. Bacterial capture was also compared to that of protein capture. It was found, surprisingly, that the patchy brushes were more protein-than bacteria-resistant. S. aureus adhesion driven by patches within otherwise protein-resistant PEG brushes was explained by the bacteria’s greater tendency to compress large areas of brush to interact with many patches. By contrast, proteins are thought to penetrate the brush at a few sites of PEO-free patches. The finding provides a mechanism for the literature reports that in-vitro protein resistance is a poor predictor of in-vitro implant failure related to cell-surface adhesion.

show abstract

“…The silicone gra copolymer, Xiameter OFX-5329, previously sold under the name Dow Corning 5329, is established to form lamellae and giant unilamellar vesicles. 15,16 It has been well studied by us 17,18 and others. 15,16 Important to the current work, the gra copolymer, while polydisperse, has an overall molecular weight of 3250 g mol À1 with 2-3 PEO side arms per each PDMS backbone, and each PEO arm containing 12 EO units.…”

Section: Introductionmentioning

confidence: 99%

Hybrid copolymer–phospholipid vesicles: phase separation resembling mixed phospholipid lamellae, but with mechanical stability and control

Chen

Santore

2015

Soft Matter

Self Cite

View full text Add to dashboard Cite

Vesicles whose bilayer membranes contain phospholipids mixed with co-polymers or surfactants comprise new hybrid materials having potential applications in drug delivery, sensors, and biomaterials. Here we describe a model polymer-phospholipid hybrid membrane system exhibiting strong similarities to binary phospholipid mixtures, but with more robust membrane mechanics. A lamella-forming graft copolymer, PDMS-co-PEO (polydimethylsiloxane-co-polyethylene oxide) was blended with a high melting temperature phospholipid, DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine), over a broad compositional range. The resulting giant hybrid unilamellar vesicles were compared qualitatively and quantitatively to analogous mixed phospholipid membranes in which a low melting temperature phospholipid, DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine), was blended with DPPC. The mechanical properties of the hybrid vesicles, even when phase separated, were robust with high lysis stresses and strains approaching those of the pure copolymer vesicles. The temperature-composition phase diagram of the hybrid vesicles closely resembled that of the mixed phospholipids; with only slightly greater nonidealities in the hybrid compared with DOPC/DPPC mixed membranes. In both systems, it was demonstrated that tension could be used to manipulate DPPC solidification into domains of patchy or striped morphologies that exhibited different tracer incorporation. The patch and stripe-shaped domains are thought to be different solid DPPC polymorphys: ripple and tilt (or gel). This work demonstrates that in mixed-phospholipid bilayers where a high-melting phospholipid solidifies on cooling, the lower-melting phospholipid may be substituted by an appropriate copolymer to improve mechanical properties while retaining the underlying membrane physics.

show abstract

Depletion versus Deflection: How Membrane Bending Can Influence Adhesion

Cited by 11 publications

References 18 publications

Easy Come Easy Go: Surfaces Containing Immobilized Nanoparticles or Isolated Polycation Chains Facilitate Removal of Captured Staphylococcus aureus by Retarding Bacterial Bond Maturation

Easy Come Easy Go: Surfaces Containing Immobilized Nanoparticles or Isolated Polycation Chains Facilitate Removal of Captured Staphylococcus aureus by Retarding Bacterial Bond Maturation

How Bacteria Adhere to Brushy PEG Surfaces: Clinging to Flaws and Compressing the Brush

Hybrid copolymer–phospholipid vesicles: phase separation resembling mixed phospholipid lamellae, but with mechanical stability and control

Contact Info

Product

Resources

About