A significant percentage of root canal treatments fail, because the procedure leaves out some bacteria that are located deep within the dentinal tubules. A group of scientists including those from Indian Institute of Science (IISc), Bengaluru, has found a way to tackle this using nanosized robots that will travel through the tubules and target the bacteria. They have also founded a company, Theranautilus, which will eventually market this technology.
Effectively harmless
Measuring no more than 300 nanometres, these spiral silica nanobots with a bit of iron embedded in them are suspended in water or water-like biocompatible medium. “There are about a billion nanorobots in 0.5 ml water. This concentration is almost a trillion times lower than the amount of silica found in a pint of beer and is effectively harmless for the human body,” explains Debayan Dasgupta, a research associate at IISc and co-founder of the company. “We inject (or rather, place them gently) in the central canal of the tooth. Then a rotating magnetic field is applied using a triaxial Helmholtz coil. The magnetic material embedded in the nanorobot has a magnetic moment that follows the applied magnetic field. This causes the nanorobot to move - like screws move into a wall.”
To the minute nanorobots, the dentinal tubules look like large channels. If the nanorobot is 300 nanometres in size, the tubules have diameters of about a few microns width and are 1,500 to 2,000 microns in length.
Once the bacterial colony is reached, the nanorobot can deploy various antibacterial strategies one of which is localised heating. “This is very effective because the bacteria we are targeting are Enterococcus faecalis, extremely hardy bacteria that are resistant to most commercially available antibiotics,” says Dr Dasgupta.
Precise control
The idea is that these nanorobots can be precisely controlled spatio-temporally. “Swarms of nanorobots can be used to target different diseased sites inside teeth to neutralise the harmful biofilms following which they can be retrieved back to the physician,” says Shanmukh Srinivas Peddi, a dental surgeon and co-founder of the company.
Studying active matter
The thought of making spiral nanorobots that can be manipulated using magnetic fields originated from a question of separating left-handed and right-handed molecules using microwave fields, nearly 12 years ago. “We realised it may be possible to do the same with colloids and magnetic fields, and subsequently developed a method of making very small magnetised spirals in large quantities,” says Prof Ambarish Ghosh, from IISc, also a co-founder of the company. “Since then these spirals were shown to be great agents to study physics of active matter, useful for biophysical measurements and microfluidic manipulations, and perhaps the holy grail, is to be able to put it in human body as biomedical nanorobots.”
The Government of India every year confers through the Technology Development Board, national awards for technology development and successful commercialisation of indigenous technology. For this year, Theranautilus has won this award in the Start-up/Deep- Tech industry category. Currently the technology is being taken through the regulatory tests for drug compliance which will be followed by animal trials.
