Researchers have developed a sensitive mass-sensor system that is capable of measuring the mass of biomolecules such as amino acids and proteins1. It can be used for diagnosing various diseases.
The mass-based detection of biomolecules is increasingly being used in biological and biomedical applications. Biomolecules are measured in units of zeptograms, where one zeptogram is roughly the mass of a single protein molecule. Unlike carbon nanotubes, which are harmful to patients' health and the environment, boron nitride nanotubes are inert and nontoxic, making them suitable for sensing the mass of tiny biomolecules.
The researchers produced the sophisticated mass-sensor system by fabricating a mass-sensing nanodevice with single-walled boron nitride nanotubes. They then assessed the feasibility of employing this mass-sensor system to measure molecules with masses on the zeptogram scale by using two biomolecules: the amino acid alanine and deoxyadenosine, a component of DNA. This was done by attaching acetone molecules to the free end of the cantilever in the mass-sensor system.
A change in the mass attached to the sensor shifted its resonant frequency. To measure mass accurately, it is critical to quantify the change in the resonant frequency induced by the attached mass. After validating the mass-sensing ability of the mass-sensor system using alanine and deoxyadenosine, the researchers used it to measure the mass of acetone molecules.
They found that the resonant frequency decreased with increasing number of acetone molecules. They measured the frequency shift induced by attaching a single acetone molecule to the sensor and then used this shift to estimate the mass of the molecule.
