Biofunctionalization of Si nanowires using a solution based technique

Abstract

Here we present a solution based functionalization technique for streptavidin (SA) protein conjugation to silicon nanowires (Si NWs). Si NWs, with a diameter of 110 nm to 130 nm and a length of 5 µm to 10 µm, were functionalized with 3-aminopropyltriethoxysilane (APTES) followed by biotin for the selective attachment of SA. High-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) showed that the Si NWs were conformally coated with 20 nm to 30 nm thick APTES, biotin, and SA layers upon functionalization. Successful attachment of each bio/organic layer was confirmed by X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. Fluorescence microscopy also demonstrated that there was an undesirable non-specific binding of the SA protein as well as a control protein, bovine serum albumin (BSA), to the APTES-coated Si NWs. However, inhibition of BSA binding and enhancement of SA binding were achieved following the biotinylation step. The biofunctionalized Si NWs show potential as label-free biosensing platforms for the specific and selective detection of biomolecules.

Ultrasensitive and miniaturized ion sensors using ionically imprinted nanostructured films

“…Two peaks were observed using high-resolution XPS on the amine group region within both control, and HClexposed samples. The higher binding energy peak ~ 402.0 eV indicates the NH3 + / NH2---H environment and the peak at ~ 399.9 eV arise from the free NH2 group [55] (Figure 3.d. and Ion imprinted silica/gold nanoparticles on the sensing layer can address the thickness and sensitivity limitations of conventional membrane-based ion-selective electrodes by offering specific binding sites directly exposed to the sample.…”