the ever-increasing threat from "superbugs" -- strains of pathogenic bacteria that are
1（不受影响的） to the
2 that
3 their
4（前辈） generations -- has forced the medical community to look for bactericidal weapons outside the realm of traditional drugs. one
5 candidate is the antimicrobial peptide (amp), one of mother nature's lesser-known defenses against infections, that kills a pathogen by creating, then expanding, nanometer-sized pores in the cell
6 until it bursts. however, before this phenomenon can be exploited as a medical therapy, researchers need a better understanding of how amps and
7 interact at the
8 level. using a novel imaging technique, a research team led by the united kingdom's national physical laboratory (npl) is
9 acquire much-needed insight into the fundamental physical and chemical processes that occur when amps
10 with membranes and form pores in them. team leader paulina d. rakowska will discuss the latest aspects of this work during the avs 60th international
11 & exhibition, which will be held oct. 27-nov. 1, 2013, in long beach, calif.
observing the formation of pores in live cell membranes by naturally occurring amps is difficult because researchers have no control over the steps in the complex process. in many cases, the membranes of the target cell leak,
12 and
13 before individual pores can expand enough to be examined. rakowska and her colleagues have overcome this obstacle by combining nanoscale imaging via two different systems, computer simulation, a made-from-scratch (de novo) amp, and lipid bilayers
14 to a solid surface (known as a supported lipid bilayer or slb).
with the ability to specifically test where and how the de novo peptide
15 to the slb, the pore formation process is opened up to direct observation. atomic force microscopy (afm) provides
topographical（地志的） (structural) imaging of the peptide-treated membrane while chemical analysis is done with high-resolution nanoscale secondary ion mass spectroscopy (nanosims).
"data from the afm images suggests that membranes change as a result of peptide action and pore formation," rakowska says. "nanosims imaging performed on the same samples reveal the precise location of peptide
16 within the membranes."
rakowska says that these observations provide the first-ever physical and visual evidence of antimicrobial pore expansion from nano-to-micrometer scale to the point of complete membrane
17. "we can now
18 the
19 by which this occurs," she explains. "we believe that the first amps
20 with the membrane
21 'recruit' others to do the same, resulting in the formation of numerous small pores. as these pores expand, they eventually lead to membrane
disintegration（瓦解，崩溃） and cell death."
the research team includes scientists from the npl, the london centre for nanotechnology, university college london, the university of
22, the university of edinburgh, freie university berlin and ibm. the team's latest publication, "nanoscale imaging reveals
23 expanding antimicrobial pores in lipid bilayers," recently appeared in the
24 of the national academy of sciences usa.
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