Substrate-bound growth of Au-Pd diblock nanowire and hybrid nanorod-plate

We expand the scope of the previously developed Active Surface Growth mode for growing substrate-bound ultrathin Pd (d = 4 nm) and Ag nanowires (d = 30 nm) in aqueous solution under ambient conditions. Using Au nanorods as the seeds, selective growth at the contact line between the rod and the substrate eventually leads to an attached Pd nanoplate. The unique growth mode also allows sequential growth of different materials via a single seed, giving substrate-bound Au-Pd diblock nanowires. The new abilities to use seed shape to pre-define the active sites and to apply sequential growth open windows for new pathways to hybrid nanostructures.

Light-emitting color barcode nanowires using polymers: nanoscale optical characteristics

We report on the light-emitting color barcode nanowires (LECB-NWs), which were fabricated by alternating the electrochemical polymerization of light-emitting polymers with various luminescence colors and efficiencies. The nanoscale photoluminescence characteristics of LECB-NWs were investigated using a laser confocal microscope with a high spatial resolution. The alternating light emissions of the LECB-NWs showed orange-yellow, red, and green colors due to the serial combination of poly(3-butylthiophene), poly(3-methylthiophene), and poly(3,4-ethylenedioxythiophene), respectively, with distinct luminescence intensities. The optical detection sensitivity and stability of LECB-NWs have been enhanced through a nanoscale Cu metal coating onto the NWs, based on surface plasmon resonance coupling and protection against oxidation. The flexibility of the LECB-NWs has been investigated through the folding and unfolding of the NWs by an applied nanotip impetus. The flexible LECB-NWs can be used as highly sensitive optical identification nanosystems for nanoscale or microscale products with complex physical shapes.

Silver-based nanodisk codes

We report a novel method for synthesizing silver-based nanodisk code (NDC) structures using on-wire lithography, where we employ milder synthetic and etching conditions than those used to synthesize the analogous gold structures. The silver structures exhibit stronger surface-enhanced Raman scattering signals than their Au counterparts at 633 and 532 nm excitation and, therefore, lead to lower limits of detection when used in the context of DNA-based detection assays. Finally, use of two enhancing nanostructured materials in one disk code dramatically increases the information storage density for encoding. For example, a disk code consisting of 5 gold disk pairs has 13 unique combinations of enhancing patterns, while one with 5 disk pairs that can be either gold or silver has 98.

Shape-coded silica nanotubes for multiplexed bioassay: rapid and reliable magnetic decoding protocols

AIMS

The recent development of 1D barcode arrays has proved their capabilities to be applicable to highly multiplexed bioassays. This article introduces two magnetic decoding protocols for suspension arrays of shape-coded silica nanotubes to process multiplexed assays rapidly and easily, which will benefit the minimization and automation of the arrays.

METHODS

In the first protocol, the magnetic nanocrystals are incorporated into the inner voids of barcoded silica nanotubes in order to give the nanotubes magnetic properties. The second protocol is performed by trapping the barcoded silica nanotubes onto streptavidin-modified magnetic beads.

RESULTS

The rapid and easy decoding process was demonstrated by applying the above two protocols to multiplexed assays, resulting in high selectivity. Furthermore, the magnetic bead-trapped barcode nanotubes provided a great opportunity to exclude the use of dye molecules in multiplexed assays by using barcode nanotubes as signals.

CONCLUSION

The rapid and easy manipulation of encoded carriers using magnetic properties could be used to develop promising suspension arrays for portable bioassays.