Surface modification of SOI-FET sensors for label-free and specific detection of short RNA analyte

A new type of surface modification of SOI-FET sensors with ultrathin sensor-probe transition layer and uncharged probes for highly specific detection of short RNA (saRNA) was suggested. Carbonyldiimidazole (CDI) or glycidoxypropyltrimethoxysilane were used as precursors of sensor-probe interface layers, together with peptide nucleic acids and new NA analogues - phosphoryl guanidine oligo(2′-OMe)ribonucleotides (PGO) as probes for RNA hybridization. RNA sequences corresponding to mRNA and microRNA-29a (cancer markers) were used as saRNA targets. Real-time saRNA detection by SOI-FET sensors and fluorescence analysis were applied. Highly specific response with femtomolar sensitivity to saRNA was demonstrated for CDI-PGO-modified sensors fabricated by optical lithography. The proposed CDI-PGO protocol of modification of Si sensor surface is a promising procedure for biomedical applications.