Nanodiamond Layers/Spots for biosensing

Nanodiamond (ND) layers are produced by the pulsed spray technique on a heated silicon substrate. By varying the number of pulses it was possible to obtain a quasi-continuous layer on the substrate surface. The use of atomic force and confocal microscopies allowed to evidence the presence of self-assembled pillar structures. The pillar formation is due to the evaporation of 1,2-dichlorethane solvent in which 250 nm nanodiamonds were dispersed and its mechanism is based on the coffee stain effect as described in detail in ref. 1. Simple bio-chips on glass and silicon substrates can be fabricated spraying ND spots arranged in an array configuration (see Figure 1a) through a mask, and are suitable for bio-applications. Specifically, the presence of nitrogen vacancy (N-V) color center in ND particles is also promising as bio-markers2. An example of spot is illustrated in Figure 1b where pillars are present (see the zoomed area of Figure 1b). Additionally, the control of the pillar position represents an important challenge for micro-functionalised emitters arranged in a chip matrix suitable for bio-screening.