Graphene based tooth tattoo could warn of bacteria and dental decay

The novel device is designed to spot bacteria at the level of single cells and report this information back using wireless technology. Created by a team at Princeton University, it represents a novel synergy between several clever materials. As well as graphene and designer peptides, an rfid tag is also part of the setup, which enables wireless communication with a detector. To begin construction, the chemists printed a small graphene grid onto a thin layer of transparent silk. This acted as a platform from which to transfer the graphene onto a range of substrates; not just teeth, but also soft tissues and intra-venous drip bags. After placing the silk-graphene 'tattoo' onto the tooth, the area was rinsed with water, dissolving the silk support to leave the ultra thin circuitry in place. The superlative properties of graphene ensured the material adhered strongly to the surface thanks to van der Waals forces. The next step was to attach bifunctional peptides to the graphene base layer. One end of the peptide was rich in aromatic residues and consequently bound to the graphene surface through pi-pi stacking interactions. The other end was formed from a naturally occurring antimicrobial protein (AMP), which has a strong affinity for three important bacterial strains. When the AMPs bind bacteria, charged regions in the pathogens' cell membranes expose the graphene to a small electric field, which modulates its conductivity. By interrogating the sensor with an external antenna, the conductance can be inferred and the bacterial concentrations determined. Although it is not yet clear whether the device can withstand repeated abrasion, such as a user brushing their teeth, the researchers believe it represents a step towards omnipresent passive medical sensors that can monitor a person's health from within. The research was published last week in the journal Nature Communications.