Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100

to penetrate a blood cell. So nanoparticles harmlessly bounce off normal blood cells. But cancer cells are different; their cell walls are riddled with large, irregular pores. The nanoparticles can enter freely into the cancer cells and deliver their medicine but leave healthy tissue untouched. So doctors do not need complicated guidance systems to steer these nanoparticles to their target. They will naturally accumulate in certain types of cancerous tumors.
    The beauty of this is that it does not require complicated and dangerous methods, which might have serious side effects. These nanoparticles are simply the right size: too big to attack normal cells but just right to penetrate a cancer cell.
    Another example is the nanoparticles created by the scientists at BINDBiosciences in Cambridge, Massachusetts. Its nanoparticles are made of polylactic acid and copolylactic acid/glycolic acid, which can hold drugs inside a molecular mesh. This creates the payload of the nanoparticle. The guidance system of the nanoparticle is the peptides that coat the particle and specifically bind to the target cell.
    What is especially appealing about this work is that these nanoparticles form by themselves, without complicated factories and chemical plants. The various chemicals are mixed together slowly, in proper sequence, under very controlled conditions, and the nanoparticles self-assemble.
    “ Because the self-assembly doesn’t require multiple complicated chemical steps, the particles are very easy to manufacture. … And we can make them on a kilogram scale, which no one else has done,” says BIND’s Omid Farokhzad, a physician at the Harvard Medical School. Already, these nanoparticles have proven their worth against prostate, breast, and lung cancer tumors in rats. By using colored dyes, one can show that these nanoparticles are accumulating in the organ in question, releasing their payload in the desired way. Clinical trials on human patients start in a few years.
    ZAPPING CANCER CELLS
    Not only can these nanoparticles seek out cancer cells and deliver chemicals to kill them, they might actually be able to kill them on the spot. The principle behind this is simple. These nanoparticles can absorb light of a certain frequency. By focusing laser light on them, they heat up, or vibrate, destroying any cancer cells in the vicinity by rupturing their cell walls. The key, therefore, is to get these nanoparticles close enough to cancer cells.
    Several groups have already developed prototypes. Scientists at the Argonne National Laboratory and the University of Chicago have created titanium dioxide nanoparticles (titanium dioxide is a common chemical found in sunscreen). This group found that they could bind these nanoparticles to an antibody that naturally seeks out certain cancer cells called glioblastoma multiforme (GBM). So these nanoparticles, by hitching a ride on this antibody, are carried to the cancer cells. Then a white light is illuminated for five minutes, heating and eventually killing the cancer cells. Studies have shown that 80 percent of the cancer cells can be destroyed in this way.
    These scientists have also devised a second way to kill cancer cells. They created tiny magnetic disks that can vibrate violently. Once these disks are led to the cancer cells, a small external magnetic field can be passed over them, causing them to shake and tear apart the cell walls of the cancer. In tests, 90 percent of the cancer cells were killed after just 10 minutes of shaking.
    This result is not a fluke. Scientists at the University of California at Santa Cruz have devised a similar system using gold nanoparticles. These particles are only 20 to 70 nanometers across and only a few atoms thick, arranged in the shape of a sphere. Scientists used a certain peptide that is known to be attracted to skin cancer cells. This peptide was made to connect with the gold nanoparticles, which then were carried to the skin cancer cells in mice. By shining an infrared laser, these gold particles could destroy the tumor cells by heating them up. “ It’s basically like putting a cancer cell in hot water and boiling it to death. The more heat the metal nanospheres generate, the better,” says Jin Zhang, one of the researchers.
    So in the future, nanotechnology will detect cancer colonies years to decades before they can form a tumor, and nanoparticles circulating in our blood might be used to destroy these cells. The basic science is being