Bringing immuno-assemblies to optoelectronics: sandwich assay integration of a nanostructured porous-silicon/gold-nanoparticle phototransistor

Abstract

The exquisite specificity of biomolecular interactions can be used to integrate photonic and electronic components into nanomaterial-based architectures. In this line, a field-effect phototransistor based on Si/porous silicon (PSi) structures was fabricated by quantitatively attaching Gold nanoparticles (AuNPs) to the PSi surface by an immunoassay. Two antibodies, linked onto PSi and AuNPs, were used against different epitopes of prostate specific antigen, the common conjugating marker for these antibodies. Under white light illumination the photocurrent increases with increasing AuNP surface density. The gate voltage is effective in decoupling electron-hole pairs created at the nanostructured PSi interface. In turn, the main effect of the immune-assembled AuNPs is the optimization of charge transport through the surface. The analysis of the photocurrent shows an outstanding spectral selectivity in the 980 ± 50 nm NIR bandwidth. This report underlines the potential of the insertion of immune-assay protocols for the development of optoelectronic devices.