MoSIx nanowires functionalization for molecular-scale connectivity Mihaela – Irina Ploscaru Jozef...
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Transcript of MoSIx nanowires functionalization for molecular-scale connectivity Mihaela – Irina Ploscaru Jozef...
MoSIx nanowires functionalization for molecular-scale connectivity
Mihaela – Irina PloscaruJozef Stefan Institute
SLONANO 2007
www.mo6.com
MoSIx nanowires
Vrbanic et al., Nanotechnology 15, 635 (2004)
1μm
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 H2O ;
one step synthesis - wool like appearance;
XRD measurements – individual nanowires are composed of Mo6 octahedral clusterssurrounded 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
Connectivity of MoSIx nanowires
A. Meden et al., Nanotechnology 16, 1578 (2005)
V. Nicolosi et al., Adv. Matter 19, 543 (2007)
Au colloidAu-Au 2.88 Å
MoSIx nanowireMo-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
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 ºC to react.
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)
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 120º angle;
2 terminal-connections - broad distribution with angles ranging from 80º to 180º.
the normals of a two (111) planes and one (100) plane form an angle of approximately 120º.
the projection of the normals of three (111) planes form a 120º angle.
Possible connectivity of the multi terminal-connectors
search for planes that can form 120º
between each other; truncate the corners; we obtain a cluster formed of
combination of (111) and (100) planes.
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.
Protein functionalization I
5 nm AuNP covered by thyroglobulin
thyroglobulinMoSIx 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.
Protein functionalization II
thyroglobulin functionalized MoSIx nanowires
GFP functionalized nanowires
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
D. VengustM. UplaznikJ. StrleA. MrzelD. Mihailovic
S. Jenko KokaljD. Turk