Current in vitro techniques cannot accurately identify small differences in concentration in samples containing few molecules in single or few cells. Nanotechnology overcomes these limitations with the possibility of measuring protein amounts down to a hundred molecules and subnanomolar concentrations and in nanoliter to picoliter volumes. The nanoscale approach, therefore, permits measurements in samples consisting of single or few cells. Atomic force microscopy (AFM) nanografting can be utilized to prepare DNA nanopatches of different sizes (from few hundreds of nanometers to few microns in size) onto which DNA-antibody conjugates can be anchored through DNA-directed immobilization. AFM height measurements are used to assess the binding of the proteins as well as their subsequent interaction with other components, such as specific proteins from the serum. Recent results have contributed to demonstrate that nanografted patch arrays are well suited for application in biosensing and could enable the fabrication of multifeature protein nanoarrays.
