Nanomaterials are versatile building blocks for fluorescent biosensors but achieving high selectivity and sensitivity is still a great challenge. We use carbon nanomaterials such as semiconducting single-walled carbon nanotubes (SWCNTs) as building blocks for optical biosensors. SWCNTs fluoresce in the nIR and their optoelectronic properties are very sensitive to changes in the chemical environment.
In general, a sensor requires a recognition unit to bind a molecule of interest and typically well-known motifs such as antibodies or aptamers are used. However, these recognition units are large compared to the size of a nanotube, which would result in poor sensitivity. Therefore we followed a new approach and created new recognition motifs by letting macromolecules such as DNA directly adsorb and fold on the SWCNT surface. Using this concept we created different organic phases around SWCNTs and we show that some of them are able to recognize interesting biomolecules. Furthermore, we studied the mechanism of signal transduction and found that conformational changes of the macromolecule change the potential landscape around the SWCNT and consequently exciton diffusion.
We demonstrate this new sensor design concept for small molecules (dopamine), proteins (fibrinogen) and sugars (lipopolysaccharides). These sensors are very useful tools for biomedical research and we apply them to image chemical communication between cells and to detect pathogens.