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Guohui Wu

Publications and source records attributed to Guohui Wu.

6 recordsLinked to original sources
PubMed2005

Interaction between lipid monolayers and poloxamer 188: an X-ray reflectivity and diffraction study.

The mechanism by which poloxamer 188 (P188) seals a damaged cell membrane is examined using the lipid monolayer as a model system. X-ray reflectivity and grazing-incidence x-ray diffraction results show that at low nominal lipid density, P188, by physically occupying the available area and phase separating from the lipids, forces the lipid molecules to pack tightly and restore the barrier function of the membrane. Upon compression to bilayer equivalent pressure, P188 is squeezed out from the lipid monolayer, allowing a graceful exit of P188 when the membrane integrity is restored.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2005

Membrane sealing by polymers.

An intact cell membrane serves as a barrier, controlling the traffic of materials going into and out of the cell. When the integrity of the membrane is compromised, its transport barrier function is also disrupted, leaving the cell vulnerable to necrosis. It has been shown that triblock copolymer surfactants can help seal structurally damaged membranes, arresting the leakage of intracellular materials. Using model lipid monolayers along with concurrent Langmuir isotherm and fluorescence microscopy measurements as well as surface X-ray scattering techniques, the nature of the interaction between lipids and a particular family of triblock copolymers in the form poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) is examined. The polymer is found to selectively insert into membranes where the lipid packing density is below that of an intact cell membrane, thus localizing its sealing effect on damaged portions of the membrane. The inserted polymer is "squeezed out" of the lipid film when the lipid packing density is increased, suggesting a mechanism for the cell to be rid of the polymer when the membrane integrity is restored.

Animals↗
PubMed2004

Lipid corralling and poloxamer squeeze-out in membranes.

Using x-ray scattering measurements we have quantitatively determined the effect of poloxamer 188 (P188), a polymer known to seal damaged membranes, on the structure of lipid monolayers. P188 selectively inserts into low lipid-density regions of the membrane and "corrals" lipid molecules to pack tightly, leading to unexpected Bragg peaks at low nominal lipid density and inducing lipid/poloxamer phase separation. At tighter lipid packing, the once inserted P188 is squeezed out, allowing the poloxamer to gracefully exit when the membrane integrity is restored.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2004

High-molecular-weight polyethylene glycol prevents lethal sepsis due to intestinal Pseudomonas aeruginosa.

BACKGROUND & AIMS: During stress, erosion of protective intestinal mucus occurs in association with adherence to and disruption of the intestinal epithelial barrier by invading opportunistic microbial pathogens. The aims of this study were to test the ability of a high-molecular-weight polyethylene glycol compound, polyethylene glycol 15-20, to protect the intestinal epithelium against microbial invasion during stress. METHODS: The ability of polyethylene glycol 15-20 to protect the intestinal epithelium against the opportunistic pathogen Pseudomonas aeruginosa was tested in cultured Caco-2 cells. Bacterial virulence gene expression, bacterial adherence, and transepithelial electrical resistance were examined in response to apical inoculation of P. aeruginosa onto Caco-2 cells. Complementary in vivo studies were performed in a murine model of lethal sepsis due to intestinal P. aeruginosa in which surgical stress (30% hepatectomy) was combined with direct inoculation of P. aeruginosa into the cecum. RESULTS: High-molecular-weight polyethylene glycol (polyethylene glycol 15-20) conferred complete protection against the barrier-dysregulating effects of P. aeruginosa in Caco-2 cells. Intestinal application of polyethylene glycol 15-20 in stressed mice protected against the lethal effects of intestinal P. aeruginosa. Mechanisms of this effect seem to involve the ability of polyethylene glycol 15-20 to distance P. aeruginosa from the intestinal epithelium and render it completely insensate to key environmental stimuli that activate its virulence. CONCLUSIONS: High-molecular-weight polyethylene glycol has the potential to function as a surrogate mucin within the intestinal tract of a stressed host by inhibiting key interactive events between colonizing microbes and their epithelial cell targets.

Animals↗
PubMed2002

A novel layer-by-layer approach to immobilization of polymers and nanoclusters.

This paper reports a simple method for the multilayer immobilization of conjugated polymers, gold nanoparticles on solid supports. Poly(phenyenevinylene) functionalized with aldehyde and aminooxy groups was chemoselectively immobilized onto both glass and gold substrates via layer-by-layer deposition. The physical properties of the thin films were characterized by grazing angle IR, TM-AFM, fluorescence, and UV-visible spectroscopy. This methodology was also successfully applied to prepare polymer/gold nanocluster alternating multilayers. The results show that this methodology provides a general route for preparing robust and functionalizable multilayer films on solid substrates with molecular-level thickness control.

Journal Article↗