The quantitative analysis of protein markers is a promising strategy in diagnosis, prognosis and
therapy monitoring of malignant tumors. The optimization of the clinical detection of these markers is directed
towards the use of a small volume system.
We developed a multiplexing nano-immuno array for proteomic analysis in low sample volumes with potential
capability of pathological screening of cancer biomarkers.
Nanografting, a tip assisted Atomic Force Microscopy (AFM) nanolithography technique is used to fabricate
DNA nanoarrays. DNA nanospots created by nanografting are exploited in order to immobilize DNA-antibody
conjugates that recognize specific proteins of interest.
The determination of the antigen content of a biological sample was obtained from the analysis of AFM
topographic profiles of the nanopatches before and after the incubation.
As a proof of principle, we focused on the biomarker Human Epidermal Growth Factor Receptor 2 (Her2),
relevant antigen found in some human cancers such as breast, lung and gastric ones.
By measuring spot height variation we performed the detection of low concentrations of the biomarker and we
were able to optimize the device sensitivity by correlating the density of the DNA-antibody conjugates on the
surface and their capability to bind the Extra Cellular Domain (ECD) of Her2.
As future perspectives we are also exploring the use of new binders, as aptamers and nanobodies (VHH), as
new tool for the recognition of specific biomarkers with higher affinity.
