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Tuesday, April 29, 2008

Folded up micrometer-scale 'voxels' for drug delivery

After starting the folds using magnetic forces, the structure is sealed using capillary action.

USC researchers have made pyramid structures that are 40 micrometers on each side

Part one is the creation of flat patterns, origami, of exactly the fold up shapes familiar to kindergarten children making paper pyramids, cubes or other solids, except that these are as small 40 micrometers (µm) on a side. (1 inch = 25,400 µm)

Instead of paper, the USC researchers created the patterns in polysilicon sitting on top of a thin film of gold, using a well-established commercial silicon wafer process called PolyMUMPs. The next step was clearing the polysilicon off the hinge areas by etching.

When the blanks were later electrocoated with permalloy to make them magnetic, the photomask used left hinge areas uncoated, to make sure they were the places that folded.

Then the folding had to be accomplished. First the researchers bent the hinges by application of magnetic force to the permalloy. Water pressure and capillary forces generated by submerging the tiny blanks in water, and drying them off did the final folding into shape.

The experiments spend considerable time comparing various methods of controlling the closure effects of water drying with simple flaps designed to close over each other to form "envelops," the directing water from different directions sequence the closing. Varying the time of trying could produce tighter seams.

Nanodiamonds 100 times cheaper, used to track cells in the body and deliver chemotherapy drugs

Taiwanese scientists have found a way to slash the cost of making the diamond chips by around 100 times.

Nanodiamond's fluorescent properties could be used to track cells moving through the body. And, last year, researchers showed they could safely deliver chemotherapy drugs.

Cheaper alternatives to nanodiamonds, such as fluorescent dyes or small chunks of semiconductor known as quantum dots, are in use already. The diamonds, though, are less prone to blinking on and off than fluorescent dyes, and are not toxic to cells, unlike quantum dots.

FNDs are usually made by firing a high-energy electron beam into commercially available diamond powder and heating it up to 800 °C. Huan-Cheng Chang and colleagues at Academia Sinica in Taipei shoot a much less intense, and hence cheaper, beam of helium ions at diamond powder to make FNDs of the same quality.

Chang's team could track the movement of a single fluorescent nanodiamond within a cell for over 3 minutes.

The researchers have also explored other applications for their cheap diamonds, such as using them to monitor stem cells in developing tissue, or to carry drugs into cells.

"In particular, we have demonstrated that FNDs are able to interact with plasmid DNA and to deliver different genes into cultured human cells," Chang told New Scientist. That could be used for gene therapy, or DNA vaccines.

Chang and his colleagues have set up a commercial operation selling their nanodiamonds and are working on making them even smaller and to fluoresce more brightly.

The cheaper diamond chips need to be made smaller, though, if they are to perform well as markers to reveal the inner workings of cells, he adds.

Friday, April 18, 2008

Tiny Magnets for more effective Gene Therapy targeting for cancer, arthritis, heart disease and more

The technique involves inserting nanomagnets into monocytes - a type of white blood cell used to carry gene therapy - and injecting the cells into the bloodstream. The researchers then placed a small magnet over the tumour to create a magnetic field and found that this attracted many more monocytes into the tumour.

This new technique could also be used to help deliver therapeutic genes in other diseases like arthritic joints or ischemic heart tissue.

Though the concept of magnetic targeting for drug and gene delivery has been around for decades, major technical hurdles have prevented its translation into a clinical therapy. By harnessing and enhancing the monocytes' innate targeting abilities, this technique offers great potential to overcome some of these barriers and bring the technology closer to the clinic.

The team are now looking at how effective magnetic targeting is at delivering a variety of different cancer-fighting genes, including ones which could stop the spread of tumours to other parts of the body.