Here comes the nanobots, not quite

Nanorobotics is the emerging technology field creating machines or robots whose components are at or close to the scale of a nanometer (10−9 meters). More specifically, nanorobotics refers to the nanotechnology engineering discipline of designing and building nanorobots, with devices ranging in size from 0.1–10 micrometers and constructed of nanoscale or molecular components. The names nanobots, nanoids, nanites, nanomachines or nanomites have also been used to describe these devices currently under research and development.
Nanomachines are largely in the research-and-development phase, but some primitive molecular machines have been tested. An example is a sensor having a switch approximately 1.5 nanometers across, capable of counting specific molecules in a chemical sample. The first useful applications of nanomachines might be in medical technology, which could be used to identify and destroy cancer cells.
Another potential application is the detection of toxic chemicals, and the measurement of their concentrations, in the environment. Rice University has demonstrated a single-molecule car developed by a chemical process and including buckyballs for wheels. It is actuated by controlling the environmental temperature and by positioning a scanning tunneling microscope tip.

Another definition is a robot that allows precision interactions with nanoscale objects, or can manipulate with nanoscale resolution. Such devices are more related to microscopy or scanning probe microscopy, instead of the description of nanorobots as molecular machine. Following the microscopy definition even a large apparatus such as an atomic force microscope can be considered a nanorobotic instrument when configured to perform nanomanipulation. For this perspective, macroscale robots or microrobots that can move with nanoscale precision can also be considered nanorobots.
Previous research by Stanford University had revealed the potential for gold nanoparticles to "tag" cancerous cells. The nanoparticles were coated in imaging reagents before being introduced to brain tumour patients. "We hypothesised that these particles, injected intravenously, would preferentially home in on tumours but not healthy brain tissue," said lead radiologist on the case Sam Gambhir. This, he added, is down to the fact that, "the tiny blood vessels that feed a brain tumour are leaky, so we hoped that the spheres would bleed out of these vessels and lodge in nearby tumour material." They did just that. Using MRI, photoacoustic and Raman imaging, the coated particles could be picked out and act as a map of the brain tumours. All that was left to do was activate the gold nanoparticles so that they could go from passive mapping tools to weapons.

The treatment involves introducing radioactive gold nanoparticles directly to a prostate tumour, causing it to shrink. Sandra Axiak-Bechtel, an assistant professor of oncology at the University of Missouri (MU) College of Veterinary Medicine explains: "We deliver the gold nanoparticles using CT guided injection; they are radioactive; and the gum arabic coating keeps the nanoparticles from aggregating (normally, with no coating, the nanoparticles clump together; with gum Arabic, they can freely diffuse through the tumour without any clumping). Because the nanoparticles are so small, the injection appears as a purple liquid, and because dog prostate tumors are so large, we inject in multiple different sites."

Thus far, it has produced no side effects in the dogs taking part and has also been successful in shrinking tumours in mice. The doses required are thousands of times smaller than those used in chemotherapy, and it can also be introduced directly to the tumour, rather than passing into disease-free tissue and organs. The side effects are monitored by taking blood tests looking for "systemic toxicity" and using CT scans to look for "local toxicity" (swelling, infection) some four weeks after treatment. researchers found no statistically significant differences in bloodwork parameters for bone marrow, kidneys, and liver. In dogs that had a CT scan four weeks after treatment, there was no evidence of tumour swelling or infection.
Another method of a medical cure is to use magnetic fields on nanoparticles, a MRI machine can be used for robotic navigation, you must know something about how it works. The bulk of the machine is a powerful, doughnut-shaped superconducting magnet that generates a magnetic field up to about 60 000 times as strong as Earth’s. In medical imaging, the field’s purpose is to align the spin of protons—the nuclei of hydrogen atoms—in the body. (A spinning proton acts as a sort of bar magnet; like a compass needle, it points in the direction of a surrounding field.) Tucked inside the big magnet is the RF coil, which transmits radio-frequency waves. When the frequency of a wave pulse matches the spin rate of the protons, the spin “flips” direction by 90 degrees. When the pulse ends, the protons relax back to their original alignment, a lower energy state. The lost energy departs as a radio signal, which is picked up by a receiver. The density of signals gives information about the molecular makeup of bodily tissues—distinguishing bone from blood, white matter from gray matter, tumors from healthy tissue.

Knowing where in the body the signals originate requires yet another set of coils. Sandwiched between the main magnet and the RF coil, the gradient coils generate a magnetic field that makes the main field stronger in some places and weaker in others. This variation changes the frequency of the protons’ signals depending on their location in the field, which allows a computer to calculate their location in the body. By pulsing the gradient and RF coils on and off in various configurations, the machine produces a three-dimensional picture. It’s the gradient field that typically makes metal objects problematic in an MRI machine. Because the magnetic force the field exerts is uneven, it can slingshot an object through the body.

Sad to say nanobots haven't achieved the level of sophistication most people would assume when looking at the photos in this article. The main success is that nanoparticles if its gold or ferro magnetic can be injected into the main diseased area and the particle (some of which will be absorbed into the affected cell)  can be heated up or have an active chemo ingredient which shrinks tumours or other forms of cancer. Bots can't navigate themselves or have the recognition skills of white blood-cells just yet. Futurists like Ray kurzweil might have ambitious hopes for a micro robot actively repairing your body, but the truth is its early days for any kind of robot. The need for a power source and computational intelligence is difficult in the normal world so nano machines will have to wait within the realms of science fiction. Despite the debunking of micro medical bots, there is advancement in small components such as nano switches and dancing robots on chips. Nanomachines on silicon surfaces controlled my electromagnetic fields or electrical changes, can be controlled in this case for a football game. Using exterior intelligence you can manipulate a complex football game but without the operator the game would not even start.
In the many many many years to come we might have more passive systems for nanoparticles with will help for medical purposes, but its a long road to reach the realms of science fiction and repair bots.
Passive systems are more feasible they might allow a slow release of drugs over time or as a diagnostic tool which sends back images or data back to the doctor. Its likely that nano scale particles will be used as a method to fight different types of cancer, or as a diagnostic tool for identifying blocked blood arteries or internal bleeding.
Considering the possibilities for a passive ways nanoparticles can help, the use of nano sized particle in drug form or using essential minerals to revitalize cells from cell death could be reachable within a few years. Possibly robots could one day exist as servants, but on a nanoscale repairing the human body is more complex than anyone can imagine...

Magnetic healing using tiny particles...

Relief in the healing power of magnets and magnetic fields has existed since the discovery of magnets several thousand years ago. In the late 18th century, Franz Anton Mesmer, an infamous charlatan, promoted the notion that he could heal with “animal magnetism.” In the 19th century magnetic healers were common – D.D. Palmer was a magnetic healer prior to founding chiropractic. Magnetic devices for everyday aches and pains have been increasingly popular recently, and today they are a multi-billion dollar industry.

Magnet therapy, magnetic therapy, or magnotherapy is an alternative medicine practice involving the use of static magnetic fields. Practitioners claim that subjecting certain parts of the body to magnetostatic fields produced by permanent magnets has beneficial health effects. These pseudoscientific physical and biological claims are unproven and no effects on health or healing have been established. Although hemoglobin, the blood protein that carries oxygen, is weakly diamagnetic (when oxygenated) or paramagnetic (when deoxygenated) the magnets used in magnetic therapy are many orders of magnitude too weak to have any measurable effect on blood flow.
Georges Lakhovsky published books and articles that claimed and attempted to demonstrate that living cells emit and receive electromagnetic radiations at their own high frequencies.
 In 1925 Lakhovsky wrote a Radio News Magazine article entitled "Curing Cancer With Ultra Radio Frequencies." In 1929 while in France he was the author of a book "The Secret of Life: Electricity, Radiation and Your Body" (French) in which he claimed and attempted to demonstrate that good or bad health was determined by the relative health of these cellular oscillations, and bacteria, cancers, and other pathogens corrupted them, causing interference with these oscillations. It was translated to English in 1935. Numerous depictions pictured in the book supposedly have Lakhovsky in a Paris, France hospital conducting clinical research treating cancer patients with before, during, and after photographs.

More recently, Dr Elena Rozhlova of Argonne National Laboratory in the United States, says subjecting the nanodiscs to a low magnetic field for around ten minutes was enough to destroy 90% of cancer cells in tests.
The researchers used a culture of glioblastoma multiforme, an aggressive form of brain cancer, to test the nanodiscs, which are made from an iron-nickel alloy. When the nanodiscs were exposed to an alternating magnetic field of between 10 to 20 Hz, it caused them to oscillate, disrupting the membranes of the cancer cells resulting in cell death. The method uses magnetic fields only one tenth the strength of those of used in previous approaches, and at much lower frequencies, avoiding the negative side effects associated with higher-strength fields.
Previous research into the use of magnetic-nanoparticles have required high magnetic fields or resulted in the accumulation of particles due to permanent magnetisation of the particles which form into clumps in the body. The researchers say this new technique offers "exciting avenues for probing cell mechanics... as well as for advancing cancer therapies." In a commentary on the report, Professor Jon Dobson of Keele University in Britain says antibodies could be used to direct the discs towards tumour cells.

Alternatively, a team of University of Texas at Arlington researchers have developed a method that uses magnetic carbon nanoparticles to target and destroy cancer cells through laser therapy - a treatment they believe could be effective in cases of skin and other cancers without damaging surrounding healthy cells.
A paper about the work by Ali R. Koymen, professor of physics, and Samarendra Mohanty, assistant professor of physics, was published in January’s edition of the Journal of Biomedical Optics.
Because these nanoparticles are magnetic, the researchers use an external magnetic field to focus them on the cancer cells. Then, they use a low-power laser to heat them and destroy the cells beneath. Koymen said. “Since only the carbon nanoparticles are affected by the laser, the method leaves the healthy tissue unharmed and it is non-toxic.”

Carbon nanoparticles produced for the cancer study varied from five to 10 nanometers wide. A human hair is about 100,000 nanometers wide. Mohanty said the carbon nanoparticles can be coated to make them attach to cancer cells once they are positioned in an organ by the magnetic field. He said the new method has several advantages over current technology and could be administered using fiber optics inside the body. “By using the magnetic field, we can make sure the carbon nanonparticles are not excreted until the near-infrared laser irradiation is finished. They are also crystalline and smaller than carbon nanotubes, which makes for less cell toxicity,” he said. The magnetic carbon nanoparticles also are fluorescent. So they can be used to enhance contrast of optical imaging of tumors along with that of MRI, Mohanty said. Mohanty said lab tests also showed that the carbon nanoparticles and a cw (continuous wave) near-infrared laser beam could be used to put a hole in the cell, revealing another potential medical use. “Without killing the cell we can heat it up a little bit and deliver drugs and genes to the cell using low power cw near-infrared laser beam. This is an additional important novelty of our photothermal approach with carbon nanoparticles,” he said.

The idea of killing cancer with heat isn't new. Researchers know that, like normal cells, cancer cells start to die when the mercury rises above 43˚C. The trick is figuring out how to kill the cancer without harming the body's own cells. One promising idea, known as magnetic hyperthermia, involves injecting minuscule "nanoparticles," basically microscopic lumps of iron oxide or other compounds, into tumors to make them magnetic. The patient is put into a magnetic field that reverses direction thousands of times every second. The magnetic nanoparticles are excited by the applied field and begin to get hot, heating and potentially destroying the surrounding cancer tissue.

Because healthy tissue is not altered by the magnetic field, it does not heat up and is not damaged. Nano particles are expected to be the next miracle in medical science, the manufacture of magnetic particles requires a broad-range of skills. They include the targeting properties for specific cells. Also creating magnetic particles would cause clumping due to their magnetic properties. The future of nano particles will eventually enable wider applications for MRI enhancement and therapeutic heating for chemotherapy compliment or cell destroying for a tumour. The early days of using magnetic fields,had half the equation of having a positive effect on the human body. Seventy years from Lakhovskys research on magnetic fields, are now agitating particles for heating specific areas turning a pseudoscience in to a real working cure and diagnostic tool...