Horizontal γ-PNA immobilization through organophosphonate chemistry for biosensing applications

Silicon-based field effect devices have been widely investigated in recent years for the label-free detection of DNA hybridization. The devices rely on detecting changes in the electrical surface potential that occur as a result of adsorbing charged DNA. To provide surface-immobilized affinity receptors for DNA hybridization, a suitable organic interface is obligatory that has a high density of receptor binding sites and a short distance between surface and probe DNA or its analogue, peptidic nucleic acid (PNA), to minimize electrolyte screening effects. In this work, we report on the bio-functionalization and characterization of silicon oxide-terminated surfaces with γ-PNA through organophosphonate interfacial chemistry. Functionalizing via attachment groups at the γ-points along the PNA backbone allows for multidentate binding of the PNA receptor in a lying configuration on the device surface, with potential application in label-free biosensing device optimization.