Surface functionalization and modification scheme of cubic boron nitride (cBN) films deposited by chemical vapor deposition was demonstrated. A homogeneous layer of amino groups was bonded covalently on the B and/or N atoms of cBN surface via a photochemical reaction with allylamine. X-ray photoelectron spectroscopy was carried out to verify comprehensively each stage of the surface modification process. Gold nanoparticles (AuNPs) were self-assembled on the amine-terminated cBN surface, and a dense and well-distributed AuNPs monolayer was obtained. Modification of amine-terminated cBN films with amine-modified DNA probes presents an example of applications as DNA biosensors.

A simple and highly selective colorimetric sensor for Cu 2+ is fabricated in this work based on the Cu 2+ -induced self-aggregation of gold nanoparticles (GNPs). In this new design, GNPs are first functionalized with cysteamine molecules on their surface through the well-known strong Au-S interaction. Then salicylaldehyde is introduced to link with the cysteamine through a simple Schiff's base reaction. Since the Schiff's bases formed on the GNPs surface may serve as efficient and selective complexing reagents for Cu 2+ , Cu 2+ can specifically react with the Schiff's base complexes and thus result in the self-assembly of GNPs accompanied with color changes. Therefore, a facile and low-cost colorimetric sensor for visual detection of Cu 2+ was developed without requirement of any instrument.