Misuse of standard antibiotics has led to the rise of drug-resistant “super” bacteria. If antibiotics don’t quite kill off all the bacteria in their host, the most drug-resistant ones are left to reproduce after their kind, producing virulent strains that refuse to die through normal treatment. Typical drugs also kill the beneficial bacteria that bodies need to function well.
When superbugs attack, get out the plastic nano-armies!
Engineers in San Jose, California have created a new form of antibiotic out of man-made nanoparticles 50,000 times smaller than the thickness of a human hair.
According to researchers, these microscopic soldiers of germ warfare are able to search out and destroy even the scariest of antibiotic-resistant bacteria. When their job of slaughtering the bacterial enemy is finished, the nanoparticles harmlessly biodegrade away.
Bacteria like methicillin-resistant Staphylococcus aureus (MRSA) infected at least 94,360 people in 2005, according to the most recent statistics from the Centers for Disease Control. About 18,650 died during their hospital stays due to this serious staph infection that has been busily defying common antibiotics.
International Business Machines (IBM) is behind a technology to use nanoparticles to take over where antibiotic drugs have failed. These newly developed plastic nanoparticles use a different method of attack, as reported in the April 2011 issue of Nature Chemistry.
The engineers have given the nanoparticles an electric charge so they are attracted to oppositely charged bacteria. James Hedrick, advanced organic materials scientist at IBM Almaden Research Center, explained:
The [electric] charge of these bacterial membranes is significantly higher than that of a healthy cell. We just tune the charge of the nanoparticle to selectively go after the dangerous microbe.
In this way, these nanoassassins can be used to target infected cells, reportedly eradicating bacteria like MRSA while leaving beneficial bacteria alone.
According to the IBM researchers, these nanoparticles also take a different approach to killing the bacteria. Rather than attacking the bacterial DNA located within the cell, these brutal plastic machetes beat down the cell walls, destroying the bacteria from the outside-in (see graphics below). Hedrick continued:
These are designed to slice the cell membrane, to rip the membrane up and eliminate the contents. It’s kind of like the way a virus would work—a virus drills a pore, empties the contents and hijacks it. This is drilling in little holes, and all the contents leak out.
Mario Raviglione, chief of the World Health Organization’s Stop TB department says that IBM’s technology:
...goes outside the scheme of current antibiotics to something that physically destroys bacteria. If this is proven to work in humans, it will simply revolutionize the way we deal with antimicrobial treatment.
While the technology sounds promising, it has yet to be tested on humans. IBM declares that the nanoparticles harmlessly degrade into an “innocuous by-product.”
It is encouraging that these microscopic machines can attack harmful bacteria without any threat that they themselves will reproduce or remain forever in the blood- stream. Yet, a great deal of testing needs to be done to make sure that the nanoparticles only at-tack the cells of the organisms they are intended to at-tack. Nanotech research has offered medical advances in a wide array of areas. Scientists picture a future world in which nanodevices target cancer cells, leaving healthy neighboring cells alone; and, in which tiny nanobots clear out clogged arteries and repair cells on the molecular level.
The following are some of the advances that have been made recently:
Enzymes
Rensselaer Polytechnic Institute Professor Marc-Olivier Coppens is using tiny polymer nanopores to protect enzymes so that they can be useful under a large range of conditions. Enzymes are proteins that speed up important chemical reactions in the body, but enzymes can denature if they are taken out of their natural environment.
Coppens’ work with nanopores offers enzymes a protective little cave to hide in, in which they cannot unfold and denature. Enzymes are about 3 nanometers (nm) in size, and Coppens designed the nanopores to be 5-12nm, just the right size to hold an enzyme like lysozyme. The enzyme retains its folded up 3-D structure so that its activity can continue at a high level outside its natural environment. This work opens up a wide variety of possibilities for enzyme research in the bio-chemical sciences.
Cancer
One of the major problems with cancer treatments is that the drugs used to fight cancer cells can often harm healthy cells as well. Getting cancer treatment to kill the cancer without killing the patient has long proved a painful task.
In separate research efforts, W. Andy Tao, an associate professor of biochemistry/ analytical chemistry at Purdue University, and Sylvain Martel and his team at Polytechnique Montreal, are using the technology of the tiny to deliver cancer drugs directly to target cancerous cells. Tao said:
Many cancer drugs are not very specific. They target many different proteins. That can have a con-sequence —what we call side effects.
Tao’s nanopolymer acts like a taxi that drives the drugs directly through the cancer cells’ front doors. What’s more, Tao’s nanopolymer is designed to be attracted to tiny beads that help escort the nanopolymer and any attached proteins back out of the system when the job is done.
Also, because the nanopolymers are water-soluble, they can help get non-water soluble drugs get to cells. Tao hopes his technology will eliminate the painful side effects that so often come along with cancer treatment. Martel’s team has successfully used an MRI system to remote control guide microcarriers through a rabbit’s body to the cancer cells in its liver.
The team placed a rabbit inside an MRI machine and, using a computerized remote control system based on magnets, were successful in guiding a microcarrier at a speed of 10 cm/s to cancer cells in the rabbit’s liver. Once there, the microcarrier released doxorubicin into the targeted part of the organ.
Like Tao, Martel hopes this technology will help beat cancer while protecting healthy cells. Professor Martel explained:
Injection and control of nanorobots inside the human body, which contains nearly 100,000 kilometers of blood vessels, is a promising avenue that could enable interventional medicine to target sites that so far have remained inaccessible using modern medical instruments such as catheters.
Martel’s research team is developing a variety of micro- and nano-sized devices that can deliver medications to the sites of tumors. The smaller devices will be able to navigate smaller blood vessels.
Humankind continually presses upward in its technological advances, offering promises of wonder cures. They offer exciting hope that the suffering caused by cancer and disease can finally be a thing of the past.
The human race has also been disappointed before, however. With each new breakthrough, an additional reminder of our ultimate corruption manages to strike. We conquered smallpox and polio only to face HIV and Mad Cow Disease. We need to be careful as we jump from new advance to new advance. An awareness of possible unforeseen results requires us to be cautious in our bio-tech race.
