A bacterial lipooligosaccharide that naturally mimics the epitope of the HIV-neutralizing antibody 2G12 as a template for vaccine design

The broadly neutralizing antibody 2G12 binds a fairly conserved cluster of oligomannose sugars on the HIV surface glycoprotein gp120, which has led to the hypothesis that these sugars pose potential vaccine targets. Here, we present the chemical analysis, antigenicity, and immunogenicity of?a bacterial lipooligosaccharide (LOS) comprised of?a manno-oligosaccharide sequence analogous to the 2G12 epitope. Antigenic similarity of the LOS to oligomannose was evidenced by 2G12 binding to the LOS and the inability of sera elicited against synthetic oligomannosides, but incapable of binding natural oligomannose, to bind the LOS. Immunization with heat-killed bacteria yielded epitope-specific serum antibodies with the capacity to bind soluble gp120. Although these sera did not exhibit specific anti-HIV activity, our data suggest that this LOS may find utility as a template for the design of glycoconjugates to target HIV.     

Polyvalent nucleic acid nanostructures

Polyvalent oligonucleotide-nanoparticle conjugates possess several unique emergent properties, including enhanced cellular uptake, high antisense bioactivity, and nuclease resistance, which hypothetically originate from the dense packing and orientation of oligonucleotides on the surface of the nanoparticle. In this Communication, we describe a new class of polyvalent nucleic acid nanostructures (PNANs), which are comprised of only cross-linked and oriented nucleic acids. We demonstrate that these particles are capable of effecting high cellular uptake and gene regulation without the need of a cationic polymer co-carrier. The PNANs also exhibit cooperative binding behavior and nuclease resistance properties.     

Evidence for the quantum birth of our universe

We present evidence for a nonsingular origin of the Universe with intial conditions determined by quantum physics and relativistic gravity. In particular, we establish that the present temperature of the microwave background and the present density of the Universe agree well with our predictions from these intial conditions, after evolution to the present age using the Einstein-Friedmann equation. Remarkably, the quantum origin for the Universe naturally allows its evolution at exactly the critical density. We also discuss the consequences of these results to some fundamental aspects of quantum physics in the early Universe.     

Laser forward transfer of silver electrodes for organic thin-film transistors

Organic thin-film transistors (OTFTs) with top- and bottom-contact configurations were fabricated using silver nano-inks printed by laser forward transfer for the gate and source/drain electrodes with pentacene and poly-4-vinylphenol as the organic semiconductor and dielectric layers, respectively. The volume of the laser-printed Ag pixels was typically in the subpicoliter (0.2–0.4 pl) range. The top-contact OTFTs resulted in lower contact resistance compared to those obtained from the bottom-contact OTFTs, and showed improved overall device performance. The top-contact OTFTs exhibited field-effect mobilities of ∼0.16 cm² V⁻¹ s⁻¹ and on/off current ratios of ∼10⁵.     

Laser decal transfer of freestanding microcantilevers and microbridges

Freestanding silver microcantilevers and microbridges were fabricated over trenches in Si substrates by the laser decal transfer process without the use of sacrificial layers or subsequent etch processes. Single laser pulses (355 nm, 30 ns FWHM) were used to directly transfer 200 nm thick silver nanopaste layers (5 ?m wide×25 ?m long) over prepatterned Si substrates with 15 ?m wide trenches. By adjusting the position of the laser spot over the substrate, it was possible to directly deposit freestanding microcantilevers 7 to 9 ?m in length or 15-?m long microbridges over the trenches. Subsequent oven curing at 250°C resulted in sintering of the Ag nanoparticles without greatly affecting the shape and form of the transfers. Laser vibrometry experiments yielded fundamental resonance frequencies in vacuum of ?1–2 MHz for the microcantilevers and ?3 MHz for the microbridges. The fitted Q-factors averaged 1500 for the microcantilevers and 1400 for the microbridges. Overall, the measured resonances of the microbridges deviated from theoretical predictions in a manner suggesting a tensile residual stress state.