Alphahemolysin has a hollow, barrel-shaped structure and inserts itself into cell membranes to create pores.

Primitive cells similar to bacteria have been created by US researchers. These synthetic cells are not truly alive, because they cannot replicate or evolve. But they can churn out proteins for days, and could be useful for drug production, as well as advancing the quest to build artificial life from scratch, nature.com said.
Vincent Noireaux and Albert Libchaber of the Rockefeller University in New York have managed to package up some of the molecular machinery of a cell inside an artificial, bacterium-sized membrane.
And they can perforate the membrane with holes that allow nutrients and energy-rich molecules to get into the cells from the surroundings.
These protocells contain all the machinery needed to generate proteins from their raw ingredients (amino acids), so they could be used as miniature factories, to produce proteins of industrial and medical value.
Such proteins, for example, insulin, are routinely produced by genetically engineered bacteria bred in fermentation vats. But artificial cells would make much simpler protein factories, perhaps more easily tailored to make specific products.
Ready-made mixtures of all the bimolecular that a cell needs for protein production is commercially available, extracted from bacteria such as Escherichia coli. These mixtures can make specific proteins, but they stop working within about two hours unless they are continually fed with raw materials and cleaned of waste products.
To enclose this biomolecule mixture inside membranes like those of natural cell walls, Noireaux and Libchaber made microscopic droplets of the cell extract suspended in oil. Soap-like molecules called phospholipids then coated the surface of these droplets in the same way that emulsifying agents surround the droplets in a salad dressing, stopping them from coalescing.
The researchers then coated the droplets with a second layer of phospholipids, to form a double layer that looks just like the membrane of a real cell.
To monitor the behavior of their cells, Noireaux and Libchaber added DNA that encodes a fluorescent protein, so that as the cells produce it, they start to glow. Whereas the bare cell extract ran out of steam after two hours, wrapping the molecules in a membrane kept the system 'alive' for more than twice as long.
To get raw materials into the protocells from the surroundings, the researchers added a bacterial gene that encodes a protein called alpha-hemolysin. This protein has a hollow, barrel-shaped structure and inserts itself into cell membranes to create pores. Once fitted with these molecular portals, the cells kept churning out the fluorescent protein for days.

Fountain pen lithography applications: (a) friction image of pattern generated with 1-octadecanethiol (ODT) on a gold sample by five scan cycles (each line) with a contact force of 1 nanoNewton at a speed of 4 microns/s. (b) lines etched with chromium etchant Selectipur into sputtered chromium.

Scientists in the Netherlands have used a micromachined "fountain pen" to write and etch sub-micron patterns on a surface with molecular "ink". The new device developed by Miko Elwenspoek and colleagues at the University of Twente is based on an atomic force microscope.
Atomic force microscopes (AFMs) were originally designed to study surfaces but they are now routinely used for surface modification as well.
In the new device built by Elwenspoek and colleagues, the ink flows from a reservoir through a channel in the cantilever that supports the tip and on to the tip itself.
Using 1-octodecanethiol as the ink, the Twente team drew lines just 0.5 microns wide on a gold substrate. The ink reacts with the gold to produce a stable monolayer structure on the substrate. In separate experiments with a commercial etchant, the tip was able to etch trenches just 0.3 microns wide and 14 nanometers deep in a chromium surface.
The team used the technique to draw and etch straight lines but any pattern could, in principle, be created. It might also be possible to reduce the width of the lines and the trenches further by sharpening the AFM tip.
Elwenspoek and co-workers say their device is an improvement on existing AFM-based surface-modification techniques, such as "dip-pen lithography", because it can hold more ink and the flow of this ink can be better controlled. Moreover, by creating a local environment around the tip, the operation of the device is not affected by humidity in the atmosphere.
"The fountain pen will extend the possibilities of probe-based nanolithography," team member Szabolcs Deladi told PhysicsWeb. "It could be used in new nanofabrication techniques like local electrochemical etching and deposition to create 3D nanostructures."
The Twente team now plans to do further work on the device itself and also on the ink, including improvements to its viscosity and wetting properties.