1. MoSIx nanowires functionalization for molecular-scale connectivity Mihaela – Irina Ploscaru Jozef Stefan Institute SLONANO 2007

2. www.mo6.com MoSIx nanowires Vrbanic et al., Nanotechnology 15, 635 (2004) 1μm1μm bundles of nanowires having a diameter from 1 µm down to 20 nm and a length of up to 5 mm ; easily disperse in low diameter bundles in organic solvents like isopropanol, methanol, ethanol, acetone, etc. and even H 2 O ; one step synthesis - wool like appearance;

3. XRD measurements – individual nanowires are composed of Mo 6 octahedral clusters surrounded by S or I atoms and connected by bridging anions of S S atoms Mo atoms I atoms A. Meden et al., Nanotechnology 16, 1578 (2005) V. Nicolosi et al., Adv. Matter 19, 543 (2007) Structure of MoSIx nanowires EXAFS measurements – the distance between Mo atoms is d=2.63 Å Mo-Mo 2.63 Å

4. Connectivity of MoSIx nanowires A. Meden et al., Nanotechnology 16, 1578 (2005) V. Nicolosi et al., Adv. Matter 19, 543 (2007) Au colloid Au-Au 2.88 Å MoSIx nanowire Mo-Mo 2.63 Å S atom functionalization of nanowires with gold; the presence of S in the structure of the nanowires ; S and Au like each other – covalent bond. gold has a fcc crystalline structure with an Au-Au atom distance of about 2.88 Å

5. Sample preparation dispersion of the nanowires in IPA or water at concentration c=0.1 mg/ml; (V. Nicolosi et al., Chem. Phys. Lett. 425, 89 (2006)) AFM studies of the dispersed nanowires; AuNPs provided by BBI International company; AFM studies of the AuNPs; MoSIx nanowires mixed with AuNPs and left for 3 days at 4 º C to react.

6. AuNPs reproducibly attach to the MoSIx nanowires; we have single attachment: one AuNP at the end of the nanowire; we have also seen multiple attachments: 2 nanowires attached to one gold cluster or 3 nanowires attached to one gold cluster. AFM analysis of functionalized nanowires M.I. Ploscaru et al., Nanoletters 7, 1445 (2007)

7. Multi terminal-connections: distribution three terminal connectors two terminal connectors schematic representation of 2 terminal-connections and AFM image; nanowires of ~ 0.5 nm connected to ~3 nm gold colloid. schematic representation of 3 terminal-connections and AFM image; nanowires of ~ 1 nm, 1.5 nm and 2 nm connected to ~ 5 nm gold colloid. 3 terminals 2 terminals 3 terminal-connections - narrow distribution centered at around 120 º angle; 2 terminal-connections - broad distribution with angles ranging from 80 º to 180 º.

8. the normals of a two (111) planes and one (100) plane form an angle of approximately 120 º. the projection of the normals of three (111) planes form a 120 º angle. Possible connectivity of the multi terminal-connectors search for planes that can form 120 º between each other; truncate the corners; we obtain a cluster formed of combination of (111) and (100) planes.

9. Control experiments with Ag nanoparticles AuNPs attach to MoSIx nanowires; we have single and also multiple attachments. sample was prepared as for Au attachment; non-attachment of AgNPs; the repulsion forces between the negatively charged colloids and negatively charged nanowires could not be surpassed.

10. Protein functionalization I 5 nm AuNP covered by thyroglobulin thyroglobulin MoSIx nanowire disulfide bonds protein of high molecular mass (660 kDa) and with surface rich in disulfide bonds dispersion of nanowires in water – mixed with gold clusters and thyroglobulin; the solution was left to react in fridge for 3 days and then analyzed under the AFM ; direct attachment of the protein to the nanowire; the gold clusters attached on the protein.

11. Protein functionalization II thyroglobulin functionalized MoSIx nanowires GFP functionalized nanowires

12. Possible applications in bio-nano technology 1. nanocircuits 2. biosensors 3. photodetection GFP can be used as a marker; fluoresces in the lower green portion of the visible spectrum; (Excitation max=488 nm; Emission max=507 nm) molecular recognition MoSIx nanowires proteins buffer solution gold-nanowire networks for possible future devices MoSIx nanowires gold colloids gold pads

13. D. Vengust M. Uplaznik J. Strle A. Mrzel D. Mihailovic S. Jenko Kokalj D. Turk